Social Distance XVI – Summer Tasks

Our first day of this year’s summer arrived on June 20th, so we’re already well into the season. We’re also well into this year’s historic pandemic season, which we all hope and trust will end before long, and not return.

We are seeing many thoughtful and creative advisories on coping with the challenges of this crisis. Here are some recent examples oriented to health and emotional well-being: 

  • Care for Your Health
  • Confirm Your Responsibilities (e.g., wear a mask)
  • Vary Your Media Choices
  • Share Your Time and Assets
  • Continue Your Protections

As we consider these recommendations  and expand upon them from our individual perspectives, we recognize them as the beginnings of good advice.

This column adds three categories of gardening activities that can provide opportunities for our creative energies, always desirable exercise, and payoffs in the quality and enjoyment of our living environments.

Care for Your Garden

At this time of the year, caring for your garden focuses on maintenance activities.

Installation of  new plants would be best scheduled for the fall, after the hottest months have passed and the rainy season will soon water your plants. Some plants, e.g., irises, Shasta daisies, etc., can be divided and replanted later in the summer. Many bulbs, e.g., daffodils, can be lifted now and replanted in the fall.

Most pruning of trees and shrubs should be done during the dormant season, but several pruning-type tasks are appropriate for the summer months. Do not prune flowering shrubs that are setting buds for the next season. Examples include lilacs, azaleas, rhododendrons, hydrangeas, and others. Summer pruning tasks include deadheading flowering plants and herbs to encourage compact growth and avoid setting of seeds and cutting back spring bloomers to promote reblooming, except when you are encouraging plants to self-spread or gathering seeds for planting or sharing. Other seasonal pruning task: removing suckers from hybridized fruit trees and shrubs (e.g., roses).

Watering plants could require regular attention. Plants in containers might need daily watering, and plants in the ground should be monitored during dry weather. Water only when the soil has become dry, and schedule watering for early morning or evening, rather than during the hottest part of the day. When irrigating late in the day, avoid the development of fungus and disease by keeping moisture off the leaves with drip irrigation or low-level hose irrigation.

Weed management could be prioritized during the summer months. Manual removal of perennial weeds is always a good idea, and removal of annual weeds should be done before they set seeds. Some gardeners find weeding to be therapeutic in some respect, but serious weed management methods could be considered, particularly short-term solarization with plastic sheeting and smothering with a layer of cardboard covered by organic mulch.

Advance Your Gardening Knowledge

The University of California’s Statewide Integrated Pest Management Program provides excellent online information on weed control. Browse to and search for “weed management.” For details of the solarization method, search the same site for “soil solarization.”

Any of the other summer-season topics can be researched on the Internet. A search for “pruning plants” could yield an unmanageable flood of information, so searching for “pruning [your plant]” is more likely to provide advice for immediate practical use. As always, searching for a plant by its botanical name works best.

Enrich Your Gardening Days

The regular pursuit of seasonally appropriate garden priorities can be a satisfying experience. To increase the likelihood of this outcome, prepare yourself with studying in advance and schedule your work sessions during cooler times and days.

Keep your emotions positive and your viruses negative and enjoy your garden.

Social Distance XV: Pruning Research

Care for Your Garden

Home gardeners might appreciate the ornamental value of a pendulous (“weeping”) tree, one that has branches that hang down. Many varieties of such trees are available for garden use. While a small number have naturally hanging branches, most weeping trees have been developed by grafting a mutated variety on to a compatible rootstock.

Basic pruning techniques apply to most trees and shrubs, but weeping trees have particular pruning requirements. This column explores the specific task of pruning a weeping tree, as an example of the general task of researching unfamiliar challenges in gardening.

A related memory illustrates the value of timely research. Several years ago, a group of Master Gardeners volunteered for a one-day project to help maintain the fairly large garden of one of the members. The garden included a young Camperdown Elm (Ulmus glabra ‘Camperdownii’). The garden owner prized the tree’s weeping and contorted branch structure, and had it growing in a large container prominently placed near her house.

The volunteer project proceeded well until one of the participants (not me!) pruned off the Camperdown Elm’s pendulous branches, which the well-intentioned volunteer regarded as misshaped.

This act of horticultural vandalism shocked the garden owner, who was very upset. The specimen tree would recover, but only after several years of new growth.

Recently, in my own garden, I contemplated an overgrown Weeping White Mulberry (Morus alba ‘Pendula’). I received this plant as a gift from a friend years ago and enjoyed its graceful branching as it grew to seven feet high. As I looked for ripe berries, I saw that the tree’s pendulous branches were reaching to the ground and spreading like a trailing gown. The effect was not unattractive, but the tree needed pruning for ideal overall size and form.

Seven foot high Weeping White Mulberry (Morus alba ‘Pendula’) needs pruning.

Surfing the Internet, I soon learned important differences in pruning a Weeping White Mulberry versus a standard White Mulberry. A major difference: for a weeping tree, prune the upward growing branches; for a standard tree, prune the downward growing branches.

Another difference: remove no more than one-third of a weeper’s branches; remove a standard’s branches as much as desired, even to the ground. It will grow back.

A basic recommendation for pruning weeping trees is the same for all trees: prune during the winter months, when the tree is in dormancy and leafless branches reveal the tree’s structure. This is vital for the Weeping White Mulberry, which bleeds heavily when pruned during its growing months.

The time to prune this beautiful tree will be during the coming winter.

Advance Your Gardening Knowledge

This situation brings to mind the carpenter’s traditional advice, and suggests a horticultural version: “Research twice, cut once.”

When the gardener confronts an unusual task and has access to the Internet, a brief search for online advice often will yield positive returns in the form of improvement and in some cases survival of valued plants. Fortunately, most plants will recover eventually from thoughtless mistreatment, but all plants will look and grow better when the gardener uses methods that are consistent with natural processes.

The first step in an Internet search is to identify the subject plant’s botanical name. If that name is not readily available, search for its common name and the botanical name will appear shortly.

Search using key words. In this column’s example, I searched for “prune weeping mulberry.”

Then, explore the links that the search has generated. Review several advisories to screen out any fringy ideas and discover the common wisdom.

Enrich Your Gardening Days

True enjoyment in gardening comes confidence in knowing that you are caring for your garden on a foundation of knowledge and experience.

Keep your emotions positive and your viruses negative and enjoy your garden.

Social Distance in Gardening, Part XI: Chelsea Chop

This week’s botanical feature is the large white crinkled blossom of the California Tree Poppy (Romneya coulteri), also called the Matilija Poppy (referring to a canyon in Ventura County, where it is abundant). It was once a contender for state flower, but the California Poppy was given that title. The California Tree Poppy grows six feet tall, and once established will spread to eight feet or more. We cut this plant to the ground in the early spring, and it is now back to its full size and flower.

California Tree Poppy

While we are social distancing, gardening keeps our emotions positive, and our viruses negative. Thinking about these objectives, we continue our exploration of accessible and productive gardening activities.

1. Care for Your Garden

Right now, late May, the “Chelsea Chop” is a useful gardening practice. This technique gets its name from Royal Horticultural Society’s Chelsea Flower Show, held around this time of the year. This exemplifies very British gardening, but it also works quite well for us colonists.

The Chelsea Chop helps control the size, shape and flowering time of certain summer-flowering plants. It applies to herbaceous perennial plants that flower in the early summer and particularly those that tend to flop.

The Chelsea Chop involves pruning back all the stems on a clump, which delays all the flowers by four-to-six weeks, or just half of the stems, which extends the plant’s flowering period further into the summer. Full pruning could be accomplished by shearing the perennial clump, while selectively pruning the clump could be done best with garden clippers.

This method encourages the production of a greater profusion of flowers. After “chopping,” fertilize the plants and provide a thorough watering.

Here are some of the herbaceous perennials that benefit from this treatment: Achillea; Asters; Campanulas; Echinacea; Heleniums; Helianthus; Nepeta; Penstemons; Phlox; Rudbeckias; Salvias (herbaceous species) and Sedums. Your garden could include some of these or other plants that would respond well to being “chopped” in late May.  

This technique does not apply to woody perennials, which require different treatment. Roses, for example, should be deadheaded regularly at this time of the year to promote blooms.

2. Advance Your Gardening Knowledge

Assign yourself to a study one of your favorite plant genera and search the Internet for information to study.

Online sources are quick, easy and free. Wikipedia, for example, has detailed articles about roses and many other garden plants. To get started, browse to and search for “List of garden plants.” It’s impressive.

You could also get a book from the public library, a local bookstore, or an online shopping service, e.g., Amazon, depending on what is available in your community.

Depending on your level of interest, you could extend the study of your favorite plant genus by learning about other plants in the same botanical family. The Abelia, for example, is a member of the Honeysuckle family (Caprifoliaceae), which includes forty-two genera. Learning about your favorite plant’s relatives will broaden your understanding of its cultivation.

3. Enrich Your Gardening Days

Gardening can be an ideal pursuit while social distancing, but it is also a highly social activity, as evidenced by the hundreds of societies that gather like-minded gardeners to share ideas, experiences, and plants. These societies are now in hiatus, but in most cases their websites are running, and freely available for interested gardeners.

To locate a society for plants of your interest, search for your selected plant genus and “plant society.” For example, search for “rose plant society.” Other approaches start with the state, e.g., “California plant society,” or a plant category, e.g., “indoor plant society.”

A brief search could lead you to information from others who share your gardening interests. You don’t have to join a society to scan their online information. If the first search doesn’t yield helpful results, try a different search.

Enjoy your garden.

Time to Prune Salvias

Salvias are sometimes called “super shrubs,” at least in this column, because they are easy to cultivate; diverse in form, size and blossom color; and well suited for gardens in summer-dry climates, like that of the Monterey Bay area.

Many salvias have blossoms in shades of red and blue. Some uncommon varieties have white or yellow blossoms. A very uncommon species is the Beach Salvia (Salvia Africana-lutea), which has rusty orange upper petals that turn to a russet-brown color.

Salvia shrub
Salvia africana-lutea (Beach Salvia)

These form, size and blossom color qualities have supported the development of a growing collection of salvias in my garden, to the point that I have lost track of the number of plants, and of their names. I do recognize the genus salvia when I come upon it; on a good day I can name several of the cultivars. My digital files include just about all these plants in my garden, and I do intend to map their locations, one of these days, as part of the ongoing mapping project.

The recent annual Hard Pruning of the Salvias in my garden required substantial help. This necessary pruning process both supports and hinders the mapping objective.

When salvias grow closely together their branches intermingle and merge into a botanical mass that defies mapping. Gardeners who grow salvias know that they benefit from hard pruning in late winter or early spring, as new growth appears at the base of the plant. Hard pruning reduces the plants to six-to-twelve inches tall. This treatment counters ranginess and promotes bushiness, which adds to their value in the landscape. It also supports mapping by enabling the determined mapper to distinguish each plant from its neighbors.

Many salvias bloom throughout the year in our moderate climate, and many have distinctive leaf forms that can be essential clues for identifying the cultivars. These characteristics certainly help in mapping, but hard pruning hinders the process by removing all blossoms and perhaps all leaves.

The ideal time for mapping a mature salvia bed, then, occurs after pruning (while the plants are small in size) and after they begin producing leaves and blooms (which happens in early spring). Salvias’ growth cycles differ somewhat, so the plants are not all in lock-step, but this strategy should work fairly well.

Another consideration related to hard pruning salvias: after plants have been pruned seasonally, they are most visible as individual plants, ready for transplanting. As with any plant, transplanting should be done as promptly to avoid drying the roots. A good practice is to dig the hole for the plant’s new location before digging the plant. This strategy avoids any lag time between listing the plant and placing it in the new hole.

Salvias can be propagated also during the pruning season through stem cuttings.

Salvia plants also can be divided at pruning time, but this method is not recommended generally because it leaves each division with a minimal boot structure.

Finally, salvia propagation can be done from seeds collected in the early fall, i.e., around September.

One or several salvias can be botanical assets in your garden.

Build Your Rose-pruning Proficiency

The Monterey Bay Rose Society will hold a series of rose pruning workshops again this year. This group of dedicated and community-spirited rosarians offers to share its expertise, so that gardeners who also appreciate the Queen of Flowers will enjoy fine blossoms during the coming season.

Species roses grow nicely with little or no care by gardeners. We occasionally read stories about “rose rustlers,” who are rose lovers who are fascinated by early rose varieties that have been lost to cultivation, and find them still growing unattended in cemeteries.

In California, for example, these historic varieties could date back to Gold Rush days. For a sampling of Sacramento’s “cemetery roses”, visit the website created by eminent garden photographer Saxon Holt,

Modern roses, particularly the popular hybrid tea roses, grow best with regular care and feeding. We prune modern roses to stimulate new growth, support good health, and promote desirable form. Well established roses respond quite well to dormant season pruning: they come back vigorously after even heavy pruning.

If you have roses in your garden and lack confidence in your pruning talents, resolve to build and apply those skills this year. We are now within the rose’s dormant period, so the next few weeks is good time to schedule such a project.

There are various ways to learn about rose pruning. When I need to learn about some aspect of gardening, I generally open relevant books in my collection or the library, or search the Internet’s vast resources on gardening techniques. To learn about pruning roses, a good place to look online is the website of the American Rose Society.

Another strategy involves searching the Internet for “pruning roses” or a similar phrase. It’s also OK to use a natural language search, e.g., “how should I prune my rose bush?”

When your search yields multiple “hits,” you can visit selected sites to find a tutorial that emboldens you to venture into your rose garden with clippers in hand.

Some gardeners will learn best from a video demonstration. If that is your preference, direct your search results by clicking on “video” at the top of the computer screen. With today’s technology, it is easy to record a video demonstration and distribute it via the Interest. It is not easy, however, to produce a video recording that communicates effectively, so you might benefit by viewing several short video clips. This can be done in one sitting, and reveal both different presentations of basic technique and variations in the methods of different gardeners.

Although much can be learned about rose pruning from printed and digital resources, the opportunity to learn directly from a friendly expert will be ideal for many gardeners, especially when the expert hands you the clippers and talks you through the process. The rosarians of the Monterey Bay Rose Society will offer the following free pruning workshops in the near future.

  • January 26, 10:00 am, San Lorenzo Nursery & Garden Center, 235 River St., Santa Cruz, CA 95060
  • January 27, 10:00 am, Mission San Antonio de Padua, Annual Cutting of the Roses, Jolon, CA. For driving directions, click here.
  • February 2, 10:00 am, Bokay Nursery, 30 Hitchcock Rd, Salinas, CA
  • February 23, 10:00 am, Alladin Nursery & Gift Shop, 2905 Freedom Blvd, Watsonville, CA 95076

For more information on the Society, visit its website.

Prune your roses during this dormant season, and expect healthy plants and great blooms in the spring.

A Cautionary Tale About Ivy

 Ivy brings a combination of pleasure and pain to the garden, and the potential to surprise gardeners who do not pay attention

Forty years ago, when I moved to my current residence, the property had a generous crop of English Ivy (Hedera helix). This most common species of the genus Hedera has some appeal in the garden. The Royal Horticultural Society has honored fourteen cultivars of H. helix with its Award of Garden Merit, reflecting the plant’s apparent good behavior in England’s climate.

Despite its British credentials, H. helix grows rampantly on the west coast of the United States. Washington and Oregon have listed it as a noxious weed. California’s Department of Food and Agriculture has not yet listed this plant as a noxious weed, but hopefully is considering that action. 

This plant had covered much of my new garden, grown into some shrubs, and overwhelmed a large evergreen tree. We removed the tree, with great regret. After several months of hacking at this invasive plant and uncounted ivy hauls to the local landfill, we had it under control. During the following years, we pulled many sprouts and still do today. The more recent sprouts probably began with bird visits, but it is not impossible that dormant ivy seeds have been lurking in my garden for decades, awaiting a taste of moisture and sunlight.

More recently, perhaps five years ago, a variegated cultivar of Algerian Ivy (H. algeriensis) caught my eye, and I planted a small amount near the base of a chimney as a groundcover. All ivies grow horizontally, and are often selected for groundcover duty. My willingness to give this plant another chance in my garden reflects both short memory and persistent optimism.

In the same area, and with similar optimism, I installed a Big Mexican Scarlet Sage (Salvia gesneriiflora). This plant quickly grew well above ten feet in height (it can reach twenty feet high in the mountains of northeastern Mexico) and spread to four separate shrubs.

These beautiful but huge plants concealed the ivy’s relentless spread. The Algerian Ivy/Big Mexican Scarlet Sage collusion continued for weeks, until the enormous salvia finished blooming, and became ready for renewal pruning (i.e., cutting it to the ground).

That drastic action revealed that the ivy had discovered the chimney that rises about thirty feet beside the house, and used it aerial roots to grow to the top of the chimney and spread in both directions across the side of the house. This growth had not been impossible to observe, but the tall shrubs close to the pathway effectively screened the situation from view.

There’s a certain charm to ivy-covered walls, but the plant eventually can cause damage and rot, and harbor unwelcome wildlife. My best choice was to have the ivy pulled down, expecting that it would take down some of the thin-brick veneer, which it did.

There is no simple solution to ivy on the house and chimney.

The next steps of this project include reattaching the missing pieces of the veneer, removing the ivy and all but one specimen of the Big Mexican Scarlet Sage, and keeping it pruned to appropriate size.

Then, the project includes shopping for plants to re-landscape the area. The UCSC Arboretum’s Fall Plant Sale will be a fine opportunity to acquire California native plants for this project. The sale begins at 10:00 a.m. tomorrow (Saturday, October 13th).

Lesson learned: if you plant any variety of ivy in your garden, check occasionally to make sure that it is growing only where you want it to grow.

Repotting a Container Plant

At a recent talk by a skillful gardener, I learned new techniques for repotting plants in containers.

First, let’s review the usual approach to this routine process.

When a plant has outgrown its container, the goal for repotting is to encourage and support the plant’s further growth.

The signs that a plant has outgrown its containers include roots growing out of the drainage hole, or roots filling the container (observed after lifting the pant from its container), or an abundance of multiple shoots or offsets. Additional signs of a pot-bound plan: a plastic nursery pot might bulge with the plant’s roots, or the soil in the container dries out quickly.

When the gardener observes the beginnings of such signs, it is time to remove the plant from its container and replant it in a larger container with fresh potting soil and irrigate to settle the soil around the roots. The common wisdom is to move the plant into the next larger container, e.g., from a one-gallon pot to a one-and-one-half gallon pot.

When a plant becomes significantly root-bound, however, good practice calls for root pruning. If roots have been circling the pot, cut through the roots with a hand pruner, and in some cases, peel away the outer layer of roots. If the roots are packed tightly in the pot, loosen the roots, cut away up to one-third of the roots, and make vertical cuts about one-third of the way up from the bottom of the root ball. These actions will stimulate the growth of new roots.

When reducing the root ball in this way, it could be appropriate to replant the plant in the same pot it had outgrown. This might be desirable when the gardener favors the container, or the container complements the plant nicely.

During this process, cut back a proportionate amount of the top growth to reduce the plant’s demand on its reduced root structure. In a short time, the plant will recover from repotting and resume vigorous growth.

Briefly, these are the usual steps to take to rescue a root bound plant and help to continue growing.

Then, Keith Taylor’s eye-opening talk and demonstration for the Monterey Bay Area Cactus & Succulent Society introduced different goals and techniques for repotting plants.

Medusa Plant by Keith Taylor

Taylor has been growing cacti and succulents for about twenty-seven years, with a previous background in bonsai cultivation. He has developed bonsai-related techniques for cultivating succulents, with an emphasis on caudiciform plants. Those are plants that develop a swollen trunk, stem or root—called a caudex—that stores moisture. These unusual plants are candidates for bonsai treatment and often favored by collectors.

(Note: The specimen shown here is a Euphorbia, which is not a caudiciform.)

Instead of repotting plants to encourage and accommodate growth, Taylor seeks to limit their size, promote larger and wider caudices, and stimulate compact top growth.

In pursuit of these goals, Taylor’s distinctive approach to repotting includes severe pruning of the plant’s roots and top growth. Without hesitation, he would cut off a plant’s taproot and close to all its fibrous roots to reduce the root ball to fit into a shallow bonsai pot. With some caudiciforms, he would cut the caudex literally in half, and wait for it to develop new roots.

Top growth pruning was equally extensive with the same objective of constraining the plant’s overall growth.

The roomful of avid gardeners of cacti and succulents understood Taylor’s bonsai pruning method, although this approach to gardening was unfamiliar them. These gardeners were familiar with limiting the size of their plants by keeping them in small containers with lean soil mixes and minimal moisture.

At the same time, many were astonished by Taylor’s relatively extreme pruning practices, which freely exceed the usual guideline to remove no more than one-third of a plant’s roots or top growth. While Taylor admitted that some of his early trials of such pruning were unsuccessful, he has found that many plants tolerate this treatment and respond well in time.

The gardeners in attendance learned that the one-third rule for pruning could be overly conservative and that more severe pruning could be effective in limiting plant growth. Bonsai-style pruning of cacti and succulents remains as a specialized form of container gardening and not everyone’s preference we learned that extreme pruning does not necessarily kill a plant.

Taylor’s distinctive pruning practices are closely related to his work in creating containers for plants. Examples of his extraordinary ceramic pots can be viewed on his website,  and his Facebook page, where he is known as “Kitoi” (his childhood nickname).

Even when we know basic gardening methods, new knowledge is always ready for discovery.

Pruning a Fig Tree and Other Plants

Pruning season is upon us. Garden priorities might simply be clearer this year, but the list of pruning tasks has grown dauntingly long.

Cotoneaster berries

Red Clusterberry

One of the most pressing tasks is to shape a Red Clusterberry (Cotoneaster lacteus) that began as a volunteer and grown to dominate one part of the garden. In the past, it has shrugged off significant pruning cuts. A common objective for pruning is to stimulate fruiting, but that is not a priority in this case.

This year’s pruning schedule began with controlling a rampant California wild grape (Vitis californica ‘Roger’s Red’), which had grown without pruning for a couple years, and found its way into the branches of nearby trees and shrubs. Whacking it back has greatly improved its overall shape and should result in a bountiful crop of grapes. I will resolve once again to cover it with netting to protect a fair share of the clusters from unknown midnight marauders.

I have also pruned the new growth on four dwarf apple trees and sprayed them with dormant oil to discourage codling moths. Friends with the California Rare Fruit Growers, noting that moths fly, emphasize the need for neighbors to spray their trees as well, but I see no other apple trees in the neighborhood. I have also planned to cut selected main branches on one apple tree (Malus ‘Cox’s Orange Pippin) to gain some freedom of movement around it. My related resolutions include another spraying one or two more times before bud break, and thinning the fruit when it grows to about the size of a golf ball, to support the development of larger fruit.

My rose pruning project is more than half completed. My approach to hard pruning roses is close to the shearing style described recently in this column. I am also shovel-pruning some under-performing roses and intending to install replacements, with a preference for “own root” roses. Pruning suckers from grafted roses is the downside of whatever benefits might flow from a superior rootstock. Related resolutions: fertilize in the spring and irrigate regularly.

My next pruning focus is a large fig tree (Dorstenia ficus ‘Black Mission’), which dates back to around 1768, was grown in the California missions, and is a very popular fig for home garden cultivation. Fruit tree specialists also recommend several other varieties. Fig trees generally produce two crops of figs each year. The first, called the breba crop, develops in the spring on last year’s growth. The second, the main fig crop, develops on the new growth and ripens in the late summer or fall. My tree has gone several years without pruning, sprawled into large size and produced relatively light crops. Its low harvest might indicate the tree’s age or the effects of drought, but it might simply benefit from pruning. I will prune it heavily during the current dormant period to improve its shape and hope to stimulate a larger main crop.

Here are the basic pruning recommendations.

  • Begins by removing any dead, diseased or otherwise unproductive wood and any sprouts growing from the base of the tree.
  • Then, remove any secondary branches that are growing at a too-narrow angle (less than 45 degrees) from the main branches.
  • Then, cut back the main branches by one-third to one-quarter.

Related resolutions include resuming an earlier plan to establish an espalier form by training branches to posts on either side of the tree, and netting the tree at the appropriate time to protect the ripening fruit from winged wildlife.

My list includes more seasonal pruning tasks, all of which should result in wonderful growth in the spring.

Pruning Roses

The gardening subject with the most advice and the greatest anxiety is pruning roses. January is the right time of the year for this task (with some inevitable exceptions, which we’ll get to), so let’s review.

Close-up of Yellow Rose

Rose ‘Graham Thomas’

Gardeners have good reasons for being uncertainty about pruning roses.

The need for pruning arises from the gardener’s priorities, not the plant’s requirements. This is evident from the existence of wild roses and so-called “cemetery roses” that thrive for generations without the care of any gardener. Pruning and other forms of rose cultivation are intended to produce more blossoms, larger blossoms, more desirable plant forms, and healthier plants.

If all roses were the same, pruning would be a simple matter, but the genus Rosa includes over 360 species, some of which are in cultivation since at least 500 B.C. This botanical diversity complicates the task: several of these species respond better to some pruning practices than to others.

Several species have been hybridized extensively, and thousands of cultivars have been available. The cultivar, however, does not determine the preferred pruning practice; more important determinants include the species and the form.

Roses are generally described in three major classifications: wild (or species) roses, old garden roses, and modern garden roses.

Old garden roses typically bloom once on old growth each season and are cold hardy. They require only minimal pruning, which is done after blooming primarily to manage the overall size and shape of the plants.

For this column, we’ll focus on modern roses, which by most accounts began in 1967.

Modern garden roses are typically hybrids derived from the very old China roses. They are most popular in today’s gardens and characterized as blooming on new growth, and ever-blooming, i.e., they continue blooming throughout the growing season. They are not cold hardy and a hard freeze can kill branches or entire plants. In the Monterey Bay area, cold weather is not a significant threat to these plants.

Pruning these plants begins with removing dead wood, and any branches that are diseased, broken or crossing other branches. These “clean up” actions prepare for cultivation pruning.

Modern garden roses generally benefit from a hard pruning to stimulate the new growth that will produce blooms. This is done during dormancy before new growth begins. In the Monterey Bay area, the best time to prune these plants is in during January and February, so right now is a good time to begin your rose year.

“Hard pruning” has various definitions, with most ranging between one-third to one-half of the canes. One approach calls for removing one-third of the canes entirely, then cutting the remaining canes by one-half.

One intriguing approach to pruning modern garden roses is to simply cut the plant down to eighteen inches in height. Shearing a rose in this way has been claimed to yield the most foliage and blossoms.

The so-called classical approach to rose pruning involves cutting canes to one-third or one-half, cutting at 45-degree angle to an outward-facing bud, opening the center of the plant for optimal light exposure, and removing branches that are thinner than a pencil. This approach yields larger stems, longer stems, and larger blossoms.

Whether you use the classical or shearing approach to hard-pruning your modern garden roses, the important message is to prune them at this time of the year. They will respond beautifully in the spring.

Pruning Evergreen Shrubs

Let’s consider evergreen shrubs, which differ from deciduous shrubs by continuing in leaf year-round. This is not the same as retaining leaves all year: evergreen shrubs sometimes are described as dropping their leaves year-round, for on-going renewal.

A separate group of evergreens is comprised of coniferous trees and shrubs, which are pruned primarily in late winter or early spring, before the appearance of new growth. It is now generally too late in the year for pruning coniferous evergreens. Exceptions include removing unwanted whole branches of spruces and junipers, which may be done at any time, and trimming yews and arborvitae can be done when they have a second flush of growth in mid-summer.

We will address the pruning of conifers next winter. These plants require minimal pruning, except as needed to control their size and shape. If you have such plants in your landscape, mark your calendar with a reminder to consider pruning needs around next February.

The larger group of evergreen shrubs should be pruned as needed in April or May, i.e., in mid-spring, after any risk of frost has passed and ideally before new growth starts. In the Monterey Bay area’s moderate climate, there is little chance of frost except in inland regions, and new growth might appear early in the spring. If the gardener initiates light pruning after new growth can be seen, the downside is that some of the plant’s energy will have been wasted, but the plant will simply replace the shoots that have been trimmed.

For pruning purposes, evergreen shrubs can be regarded in one of three groups.

  • Early flowering. Examples include Berberis, Camellia, Ceanothus, Daphne, Mahonia, Pieris, Azalea, Rhododendron, and Viburnum. They bloom in winter, spring or early summer. Many shrubs in this group should be pruned only lightly and deadheaded.
  • Late flowering. Examples include Eucryphia (Leatherwood), and laurels (e.g., English Laurel). These plants bloom in summer and late autumn on either old or new growth. They need little pruning.
  • Mid-season flowering. Examples include Calluna (Heather), Erica, Lavandula (Lavender), Santolina, and Thymus (Thyme). These bloom on old growth in spring or early summer, or on new growth in late summer and autumn. Generally, pruning involves removing shoots after flowering to about one inch of the previous year’s growth.

Daphne Bloom

Daphne odora ‘Aureomarginata” in bloom

The pruning strategy for these plants follows these following basic steps;

First, remove any diseased, damaged, or dead branches. They will not heal themselves and could spread disease, so prompt removal benefits the healthy parts of the plant and helps the gardener to evaluate other needs for pruning.

The second step, then, is to remove branches that are crowding other branches, or compromising the desired appearance of the shrub. The pruning objectives might include reducing the overall size of the plant, either to work better within the landscape plan or to clear a walkway.

A common problem arises when an established, healthy plant grows larger than expected or wanted. Such outcomes should not be surprising: information on the mature size of a plant is readily available at the garden center or in a reference book or website. A bit of research during plant selection can save future effort.

Shrubs that have become badly overgrown might need rejuvenation pruning. In such cases, remove one-third to one-half of the branches to ground level, and reduce all other branches by one-third. In the following two years, remove half of the older branches to ground level.

Pruning time also should be used as an opportunity to evaluate the overall health of the plant. If it has sparse or leggy growth, consider the need for greater exposure to sunlight. For example, a nearby tree might have grown to shade a plant that grows best in full sun, or the plant might have been installed originally in partial shade. In such cases, prune the tree that blocks the sun, or move the shrub to a sunnier spot.

Another factor limiting the plant’s growth might be poor soil, which can be treated with fertilization during the growth period, and regular applications of compost. The gardener should avoid planting in soil with minimal nutrient value, e.g., sandy soil or sub-soil (lacking loamy top soil). If this is unavoidable, consider planting in better soil in mounds, raised beds, or containers.

A third factor might be insufficient drainage. Some shrubs thrive in soggy soil, but the large majority need oxygen at their roots, so the surrounding soil must be allowed to dry out between irrigations. This can be a problem that results when plants are placed in low-lying areas, or in moisture-retaining clay soil.

The third step in pruning includes mulching and feeding. These actions minimize weeds around the plant and help the plant to grow.

The final step is to stand back to appreciate a job well done.