Gardening to Save the Planet

Posted on September 7, 2014 by tomkarwin

We are learning about humanity’s many impacts on the near and distant future of our planet. Some people are in denial about these impacts, while others are concerned and ready to do whatever we can to ensure that our Earth will support future generations.

To support and encourage such positive action, leading botanist Peter Raven will visit the UCSC Arboretum next week to meet with UCSC faculty and staff, and present a public talk, “Saving Plants, Saving Ourselves.” Raven will present an informed update on the increasing threats to Earth’s environment, and emphasize the special role of public gardens in conserving plants that could be lost through habitat loss and climate change.

Peter Raven has a long friendship with the UCSC Arboretum, and a national reputation as a conservationist and advocate of global biodiversity: Time magazine hailed him as a Hero of the Planet. His visit to the Monterey Bay area inspires us to reflect on the home gardener’s unique role in saving the planet.

Here are ten everyday practices that gardeners can apply to help sustain the environment and protect plant diversity.

Irrigate your garden wisely, using drip technology to deliver water only where needed, and mulch (organic or inorganic) to minimize evaporation and weed growth.
Recycle household water into the garden, using plant-friendly soaps and detergents.
Prune your acquisitions of consumer goods that bury our landfills and clutter our environment…and that you really don’t need.
Propagate plants that Nature’s pollinators (bees and other insects, bats and birds) love and need to survive. Clusters of flowering plants will enrich your landscape.
Conserve biodiversity by protecting endangered species and including rare and threatened California native plants in your landscape. (Visit the California Native Plant Society’s website, www.rareplants.cnps.org/ for info.)
Nourish your plants with organic fertilizers, and discontinue uses of artificial chemicals
Control plant-eating insects with insect predators and organic insecticides. Use physical barriers and non-toxic deterrents to control other plant-eaters, e.g., snails, gophers and deer,
Select plants that are native to California or other summer-dry climates, to enable their healthy growth, support wildlife and ease your gardening workload.
Compost the “carbon-rich” fantasies of climate change deniers with the “nitrogen-rich” facts of the world’s scientists to promote wise stewardship of the environment. (Alto, keep all biomass on the property by composting green garden waste!)
Cultivate these good practices among your friends and neighbors.

The UCSC Arboretum employs these practices regularly, and assigns high priority to its work in plant conservation.

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This photo shows UCSC student Austin Robey and Arboretum volunteer Tim Forsell as they replanted endangered California native manzanita shrubs on a steep slope near the Point Sur State Historic Park and Lighthouse. The Arboretum’s Brett Hall coordinated the conservation project.

Your practices in your own garden also could help to save the planet. A good start would be to attend Peter Raven’s talk..

***

Registrations for the Peter Raven talk sold out quickly. To receive timely announcements of future events at the Arboretum, visit arboretum.ucsc.edu/get-involved/.

If you would like to sponsor an educational event at the UC Santa Cruz Arboretum, contact Jennifer Macotto, 831-427-2998 or jmacotto@ucsc.edu.

For information on how you could help save a rare species: visit arboretum.ucsc.edu/education/plant-sponsorship/.

Are Your Plants Dying?

Posted on September 7, 2014 by tomkarwin

Of course they are!

All living plants age and eventually die. The only exceptions are plants that are man-made from plastic or other materials.

The aging process, called senescence, begins after the plant achieves reproductive maturity and ends when the plants dies.

Senescence is an inevitable component of plant cultivation, so gardeners should recognize and understand the process, and appreciate its benefits.

There are several kinds of senescence.

Whole Plant Senescence occurs when the entire plant dies after seed production. This occurs with annual and biennial plants, and also with monocarpic plants, e.g., the Century Plant (Agave Americana), which can grow for several years before producing seeds. The benefits of this kind of senescence include genetic diversity (each seed cycle combines genes from different plants) and increased survivability (the plant uses it resources for producing seeds, rather overwintering).

Sequential Senescence is typical of perennial plants, in which the leaves age and die, but the main shoots continue to produce new buds and leaves. This is characteristic of woody perennials, i.e., shrubs and trees, which build their roots and aboveground structure year after year, and thus increase their abilities to produce seeds and compete with other plants. A good example is the apple tree, and many other fruit-bearing trees. The tradeoff is less genetic diversity for the tree itself, although achieve genetic diversity through its fruits. Still, the tree is more vulnerable to rapid environmental changes and attacks of insects or diseases.

Shoot Senescence occurs with certain plants that die to the ground after flowering and fruiting, but retain their belowground stems and roots, which produce new shoots in the following season. Examples of such plants include the banana and the gladiola, as well as virtually all other bulbous plants.

Synchronous Senescence is controlled by environmental factors. In this process, temperate deciduous trees drop their leaves in response to seasonal changes in the temperature, typically as in late autumn. At this period, the leaves’ green chlorophyll decomposes, revealing the leaves’ carotenes, which may be yellow, orange or orange-red. In California, we look for fall color in elms, many Japanese maples, Chinese Pistach, Liquidamber, Bradford pear, flowing dogwood and others. The living fossil Maidenhair Tree (Ginkgo biloba) is noteworthy because in the fall its leaves change from green to saffron yellow, and then all fall not quite simultaneously, but within a short period.

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Woody plants also will self-prune during the growing season: leafy shoots that are not growing well die off, and the plant re-directs its nutrients to other shoots. I see this impressive self-regulatory function mostly with interior shoots that may lack sufficient exposure to sunlight. Similar, but less visible self-pruning also occurs with roots.

Gardeners need to be alert to dieback that can occur in addition to the natural processes of senescence. Such diebacks could result from controllable environmental impacts, from temperature, wind or sun exposure, insects, diseases, or herbivores; water shortages; or nutritional deficiencies. The first step in correcting a problem is analyzing its cause.

Garden Plants on the Move (Moving Trees & Shrubs)

Posted on August 23, 2014 by tomkarwin

Autumn in the garden is a good time to prepare for relocating shrubs or trees that would look or grow better in a different location.

If the thought of moving a shrub or tree troubles you, recognize that even good plants need not be permanent. Here are some reasons for moving a healthy shrub or tree.

The tree or shrub has grown so large it’s crowding a walkway or other plants.
Other nearby plants have grown so large that they are shading a plant that needs sun.
Other nearby plants are now gone, exposing a plant that needs shade.
The tree or shrub is needed elsewhere in the landscape.
The gardener wishes to install a new feature, and the tree or shrub is in the way.
The gardener has wishes to establish a thematic plant bed where an off-theme tree or shrub is growing.

When preparing to relocate a plant, first decide on where it will go. Examine the new location to ensure that it is the right place for this particular plant. Confirm that the soil is suitable, the drainage is good, and the exposure it right for the plant. Finally, make certain that the new spot could accommodate the plant when it is fully grown. Then, dig a hole twice the width of the intended root ball.

Ideally, prune the roots to protect against transplant shock. This involves digging a trench around the plant, outside the intended root ball, refilling the trench and watering to settle the soil. Root-prune in March for plants to be moved in October, and in October for plants to be moved in March.

Then, plan how to move the plant, taking its size into consideration.

Small Shrubs and Trees

For a shrub less than three feet tall, or a tree with a trunk is less than one inch wide, you could move it bareroot, i.e., without digging up a root ball. To move such a smaller plant bareroot, dig a trench around it, cutting the longer roots, wash the soil off the lateral roots, and use a flat shovel to remove the soil under the plant. Keep the roots moist until you are ready to transplant.

Not-so-small Shrubs and Trees

If you are preparing to move a plant that is between three and five feet high, decide how large a root ball to provide. For industry standards for transplanting different plants of various sizes, visit the website, americanhort.org and search for “root ball.” For example, moving a five-foot tree or shrub requires an eighteen-inch wide root ball. A root ball of that size could weigh 250 pounds, so plan for the appropriate equipment and helpers.

Larger Shrubs and Trees

Most gardeners will hire a tree service to move a tree or shrub that is larger than five feet high. If you prefer to do such work yourself, I will say “best wishes,” and predict that you will have professionals do your next transplant.

Really Large Trees

Even very large trees—up to forty-five feet high—can be moved successfully, if not cheaply. The widely available tree spade uses an array of large shovels to dig a conical divot to pluck a plant from the ground, and deposit it in a matching hole. For video clips of tree spades in various sizes, browse to YouTube.com and search for “tree spade.” To see an interesting DIY device, search YouTube for “Tree Toad 24 inch Tree Transplanter.”

A mechanized tree spade makes transplanting large bushes and small or medium trees a much easier proposition. Photo: Dutchman Industries

A newer technology for moving larger plants is the “air tool,” which uses compressed air to blow soil away from a tree’s roots. This bareroot method avoids pruning or breaking the roots, so the plant experiences little trauma and quickly resumes its usual growth cycle. To see a brief video demo of the air tool, visit growingwisdom.com, click on “Trees & Shrubs” and scroll to the link, “How to Move Large Trees Using an Air Tool.”

After moving a tree or shrub, transplanting herbaceous perennials is easy!

Back to the Future Garden (Bulbs)

Posted on August 16, 2014 by tomkarwin

An important aspect of the art of gardening is working backwards, so let’s begin today by visualizing a stunning display of spring bulbs in your garden next April.

“Bulbs” include all plants that grow from bulbs, tubers, corms, or rhizomes. Plants with underground storage organs are correctly referred to as “geophytes.”

There are a great many plants in this category, with a stunning range of colors and forms. The large majority of geophytes are native to the world’s Mediterranean climate regions, which includes coastal California; they have evolved to thrive in climates like that of the Monterey Bay area.

For your spring vision to become real, you will need to plant your bulbs this year, in the early fall. You could plant as early as August, or as late as November, but a good time to target is September.

To have bulbs to plant in September, order them in July or August. You could buy bulbs later at a local garden center, but retailers necessarily stock mostly the very popular varieties. Ordering by mail will let you choose from an enormous range of possibilities, and early orders are most likely to secure the largest, most productive bulbs.

If you acquire your bulbs before you are ready to plant, store them in a dry, well-ventilated place.

Before you buy bulbs, you should have a plan for planting. The easy part of planning for a display of spring bulbs is to identify space in your garden that receives—ideally—at least six hours of sunlight daily, and that drains well (no puddles!). There are also a good number of bulbs that will do quite well in partial shade, but if you intend to plant in a shadier area, select bulbs with that condition in mind.

Bulbs also can be grown successfully in containers, given sufficient sun exposure and very well-drained soil. Typical planting mixes are fine, but should be amended with horticultural sand, pumice, crushed lava rock, or other material to promote drainage.

Your design could mass your bulbs for a large display of one or several varieties, or place several small cluster displays among other plants in the landscape. The scale of your display will guide your decision on the number of bulbs to order. Growers usually recommend spacing for specific plants, but three times the width of bulb is generally OK. Wider spacing will provide room for increases.

The more popular species of bulbs that do not require winter chill to perform well include Daffodil, Crocus, Grape Hyacinth, Allium, Crown Imperial and Snowdrop (Galanthus). Others bloom their best after several days of chill: Tulip, Hyacinth, Siberian Squill, Anemone, Freesia (but some varieties will do fine without special handling).

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Good mail-order catalogs indicate which bulbs will grow well in Zone 9, which includes the Monterey Bay area, and offer pre-chilled bulbs.

To benefit from the full range of mail-order options, select some so-called “minor bulbs,” i.e., those not included among the most familiar species. Adventuresome gardeners leave the beaten path to discover the most interesting blossoms.

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Caption: The Yellow Foxtail Lily (Eremurus stenophyllus) grows 4-5 feet high, with hundreds of star-shaped flowers. Photo: Brecks.com online catalog.

Good preparation of the planting area(s) involves removing weeds, loosening the soil, and digging in a three-inch layer of organic compost. If you have clay soil, dig in six inches of compost. This healthful exercise could be enjoyed after ordering the bulbs.

Bulbs are traditionally planted in random arrangements, following their natural spread. Planting bulbs in rows is so 19^th Century.

The actual planting of bulbs in well-prepared beds can be quick and easy. The usual rule for planting depth is three times the height of the bulb. Stab a trowel into the ground, pull it toward you to open a planting hole, drop in the bulb, pointy side up, and cover.

If gophers or deer snack in your garden, put a handful of gravel at the bottom of the hole, and spray your bulbs in a bucket before planting with a repellent like Deer Off, Liquid Fence or Repel. You might need to plant in gopher baskets, which of course slows the process.

Start now to prepare for next spring’s pleasing display of bulb blossoms.

Visit Cindi’s Catalog of Garden Catalogs for many mail-order suppliers of bulbs.
The good ones include the following:

Breck’s Bulbs: click on “Spring Bulbs” and “Other Spring Bulbs” for minor bulbs;
Brent and Becky’s Bulbs, well-established grower, with a good search tool;
Bill the Bulb Baron, a local grower, with fields in Moss Landing;
Far West Bulb Farm, specializing in California native bulbs;
McClure & Zimmerman, offering a variety of uncommon bulbs;
Telos Rare Bulbs, species bulbs from exotic places;
Van Bourgondien Bros., good prices for larger volume orders.

Finally, visit the website of the Pacific Bulb Society for non-commercial information. Click on the link to “Pacific Bulb Society Wiki” for photos and descriptions by avid growers of geophytes.

Flood of Gardening Information

Posted on August 9, 2014 by tomkarwin

This week, I was delighted to see small pink “church bells” appear for the first time in a shady area of my garden. (Click to enlarge)

I had added three Azores Bellflowers several weeks ago, and hadn’t given them special care, except for infrequent watering. They have settled in nicely on their own, and begun decorating that bed with their attractive flowers. Their botanical name is Azorina vidalii (previously Campanula vidalii) and they were discovered by a naval officer, Captain Vidal, on The Island of the Flowers, in the Archipelago of the Azores.

To learn more about this or any other plant that piques your interest, a good place to look is the online encyclopedia, Wikipedia. Just browse to the website and enter the botanical name of the plant. With rare exceptions, Wikipedia quickly and easily provides detailed information on garden-worthy plants. It’s even worth trying when you have only a plant’s common name or cultivar name.

Wikipedia is just one example of the flood of gardening information that exists on the Internet. Another free online resource for gardeners is Pinterest, which is a vast collection of photographs that individuals and businesses have shared. Called a “visual discovery tool,” Pinterest has images in many categories, and it is searchable by keywords. To use this tool, browse to the website and search for what interests you at the moment. For example, try “gardening” or “garden steps” or “garden ponds,” just to see what turns up.

Two more examples:

YouTube offers many brief “how to” video recordings on garden topics, e.g. planting, pruning, irrigation and others. Visit the website and search for your current interest. For example, a friend who read my column on summer pruning of apple trees asked about pruning plum trees. A quick search of YouTube for “summer pruning of fruit trees” yielded several different video demonstrations of pruning plums, apriums, and others.

Recently, I discovered another resource: ISSUU, an online collection of magazines on many subjects. The collection features some popular selections, but is comprised mostly of relatively esoteric and exotic periodicals. Browse to the website and search for “gardening” or “gardens” to release a flood torrent of mostly unfamiliar but typically well-done publications that relate to the search term. The entries are listed in random order, some are outdated (but still interesting), and a few are mail order catalogs. ISSUU offers ample reading material for the gardener who is tuckered out, rained out or looking out for inspiration.

Together, ISSUU, Pinterest, YouTube and Wikipedia offer free floods of factual information for avid gardeners who have access to an Internet-connected computer. Invest a few minutes to explore these online resources, and use them when you need answers to gardening questions, or fresh ideas for your gardening adventures.

There are of course a very large number of additional resources for gardeners on the Internet.

An exceptionally helpful website for selecting and locating particular plants is
Cyndi’s Catalog of Garden Catalogs. This website provides links to a long list of catalogs for mail ordering plants of all kinds. The catalogs are organized by plant genera, with a separate list of general catalogs, plus numerous links to valuable websites under the header “General Advice and Reference.”

A little time spent in exploring Cyndi’s collection of website links will help to discover seemingly unlimited information on all aspects of gardening.

Still More

More and more people are using the broadband Internet, and find it useful for a variety of reasons. People who do not yet do so often lack understanding of the benefits of broadband access, or need to develop digital literacy. Today’s column provides a glimpse of the Internet’s value for avid gardeners.

The Internet also provides access to free education in digital literacy, through a government-sponsored website, Digital Literacy.gov, which offers self-tests and tutorials. To join the Digital Age, visit the website and get started.

Go to “Topics” and click on “Basic Computing” and got to “New User Tutorial”
After that training (and still in “Basic Computing”) click on “Basic Computer Skills”
When finished with that training, click on “Basic Computer Quiz—Part I” to see how much you have learned.

Congratulations! You have broken the ice! This Digital Literacy website includes many more tutorials to help you become a Digital Information Gardener (DIG).

Summer Pruning of Apple Trees

Posted on August 3, 2014 by tomkarwin

Do you have one or more apple trees that have vigorous new upright growth, like the shoots, often called water sprouts, shown in the picture? This photo shows new growth on an espaliered Gala apple in my garden, before and after pruning (click to enlarge).

BEFORE PRUNING

AFTER PRUNING

Those shoots, usually at least one foot in length, are the tree’s response to heavy pruning during the dormant season, and represent an effort to restore the balance between the canopy and the root system.

Water sprouts are unlikely ever to bear fruit. Instead, they sap the tree’s energy and shade the interior of the tree, slowing the development of vertical growth, and the time for dealing that problem begins now. The period from early August to mid-September is the ideal time for summer pruning, after the new branches have set their terminal buds. This means that the branch has stopped growing for the season, so pruning will not stimulate additional growth. The best practice is to remove the water sprouts with their terminal buds.

Note that some new shoots will be shorter, and horizontal or nearly horizontal. Horizontal shoots (properly called “laterals”) are more likely eventually to bear fruit, so they are treated differently from the vertical or near-vertical shoots.

First, consider training these laterals to close to horizontal, using string or V=notched spreaders, to support fruiting.

Then the recommended treatment is to prune these laterals back to three buds of new growth after the cluster of leaves at its base. This will stimulate the formation of fruiting buds.

Oren Martin, the gardening guru at UC Santa Cruz’s Farm & Garden, says this three-bud pruning system is based on the advice of Louise Lorette a French orchardist of the early 20^th century.

Pruning your apple tree’s water sprouts and laterals in this manner can be a repetitious and fussy detailed task, but it really will not take long and will contribute significantly to your tree’s vigor and productivity.

My practice is to listen to National Public Radio on a portable radio while pursuing repetitious tasks like pruning or weeding. That way I can feel like both a conscientious gardener and an informed citizen.

Summer pruning of apple trees is distinctly different from winter pruning, which should focus on the tree’s structure and overall form. Summer pruning, by contrast, emphasizes the tree’s details, keeps sunlight flowing to the interior and supports fruit production

The time for structural pruning of an apple tree is late winter while the tree is dormant and leafless. Winter pruning can stimulate the growth of water sprouts, which are pruned in summer when the tree is not producing new growth. This practice results in less pruning down the line.

When the dormant season comes again, we’ll review the art of winter pruning. Now, during the summer months, pick up your clippers and snip away at those water sprouts.

Low-Maintenance Garden Themes

Posted on July 27, 2014 by tomkarwin

Designing a garden bed around a theme yields practical and aesthetic benefits.

The aesthetic benefit of thematic garden design rests on the relationships among the plants: they are linked by being members of the class defined by the theme. In that respect, a thematic group is more coherent, aesthetically, than the ever-popular “grab-bag” approach to plant selection.

The practical benefit is a plan for selecting plants from the hundreds of thousands of available varieties. Once the gardener has chosen a theme, he or she has reduced the universe of possible plants to consider. This one action narrows the selection task and supports close evaluation of options.

A garden design theme is simply a concept to which plants relate. This definition embraces a very wide range of possible themes, which could be a single color or combination of blossom colors; a plant genus, e.g., rose, iris, daffodil; size, e.g., miniatures; bee-friendly, etc.

For today’s topic, consider a progression of four themes for low-maintenance gardening.

Theme #1: Zone-appropriate Plants. Every gardener should know the U.S. Department of Agriculture’s Plant Hardiness Zone in which his or her garden exists. The Monterey Bay area is in USDA Zone 9b, where minimum temperatures are in the 25–30 degree range; plants marked for Zone 9 should survive cold spells in that range. A great many plants are that hardy, so this theme excludes only plants that are vulnerable to cold and therefore high-maintenance. Nurseries also use UCDA zones to indicate the preferred zone for given plants. Plants that are rated for Zones 10 or 11 usually will thrive best in very warm climates, not in Zone 9.

Theme #2: Mediterranean Climate Plants. These are plants that have evolved to grow well in the world’s areas that have dry summers and moderate winters. These areas (again) are native to the central coast of California, the central coast of Chile, the southwestern coast of Australia, South Africa and the Mediterranean basin. A large number of plants are suitable for this theme, but this category still is significantly smaller that Theme #1.

Theme #3: California Native Plants. This theme is within Theme #2, of course, but it stands apart from the others because includes plants that are both suitable for the Mediterranean climate and the soils and fauna of this state. Soil chemistry and symbiotic relationships with birds, mammals, insects and microbial life contribute significantly to the growth of plants, and, ultimately, the success of the gardener.

Theme #4: Native Plant Communities. A great variety of plants are native to California, and many have evolved to grow best in specific environments within the state, and in communities with specific other plants. An oak woodland plant community is certainly different from one that occurs naturally on coastal bluffs and cliffs. For the ultimate in low-maintenance gardening, adopt a thematic design for a California native plant community that would be appropriate for your garden setting.

Consider a thematic design for each garden bed or each large area of your garden. Plant selection will transform a random process to a purposeful activity.

Books for Thematic Designs

Zone-appropriate Plants
The New Western Garden Book (Sunset, 2012)

Mediterranean Plants
Plant Life in the World’s Mediterranean Climates (Dalman & Ornduff, 1998)

California Native Plants
California Native Plants for the Garden (Bornstein, Fross & O’Brien, 2005)

Native Plant Communities
Designing California Native Gardens: The Plant Community Approach to Artful, Ecological Gardens (Keator, Middlebrook & Faber, 2007)

Gardening with Exotics

Posted on July 20, 2014 by tomkarwin

Many of the plants we enjoy in our gardens produce flowers. We also enjoy many plants for their foliage, but the flowering plants, called angiosperms, are the ones that attract our attention.

The angiosperms, which first developed about 245 million years ago, have grown to dominate the terrestrial ecosystems, exceeded only by the coniferous forests.

There are about 260,000 species of angiosperms, and the growers of the most popular garden species have produced countless selections, hybrids and cultivars. When we visit our local garden centers or flip through catalogs of mail order plants, we see most often those variations of the most familiar plants.

Some avid gardeners eagerly seek the latest introductions of roses, irises, petunias and other and take pleasure in being among the first in their communities to have the hybridizers’ newest achievements. Each year, when we might think that new versions of popular plants are not possible, we find unexpected colors, new color combinations, more vigorous or more floriferous producers, and plants that have been bred to be more resistant to pests and diseases.

These new introductions are often the most costly plants offered, reflecting both their appeal to consumers and the costs of development and introduction. The most enthusiastic collectors of the best and latest do not flinch and gladly pay the premium prices.

Gardeners who appreciate unfamiliar and interesting plants have alternatives to each year’s new crop of high-priced new introductions. The vast array of angiosperms includes many exotic, garden-worthy plants with gorgeous blossoms that are rarely seen in garden centers or catalogs, and are very much worth the time and attention of gardeners.

The local gardener’s search for exotic flowers will be most successful when focused on plants that are well suited for the special growing conditions of the Monterey Bay area. These include plants from the world’s “summer-dry” climate regions, including coastal California, the central coast of Chile, the southwestern coast of Australia, South Africa and of course the Mediterranean basin.

A wide selection of interesting plants is native to these areas, and will succeed in the Monterey Bay area with routine care.

One example of an interesting exotic from a summer-dry climate is the Giant White Squill (Urginea maritima), which is a member of the Asparagus family (Asparagaceae). This plant, which is from the Mediterranean basin, has an enormous bulb (perhaps the largest of any plant), and an unusual annual cycle. It grows in the winter: large leaves appear from November to about May, when they yellow and dry, and the plant goes dormant. Then, in late July, it sends up a dramatic flower spike, up to five feet high. Each spike has a raceme of hundreds of tiny white or pinkish-red flowers.

Click to enlarge. Click to Enlarge Unusual plants that will grow w ell in your climate, can add a good measure of interest to your garden. Watch for exotic selections in your garden center or garden catalogs.

The Giant White Squill has interesting characteristics.

All parts of the plant are toxic.
The flower stalks will continue to blossom after being cut, so you could bring a stalk indoors to watch the progressive opening of the blossoms.

For information about “uncommon and astonishing” plants, visit the website of Louis the Plant Geek. His website has information on many exotic plants, and includes photos of the Giant White Squill in leaf.

Gardeners oriented to reading could look for the book, Bizarre Botanicals, by Larry Mellichamp and Paula Gross (Timber Press, 2010). It could be in your local public library or book store, and is currently available on Amazon.com.

Wherever you find exotic plants for your garden, always favor plants that are suitable for your garden’s growing conditions. For most gardeners in the Monterey Bay area, remember that such plants are native to the Mediterranean climate region.

Be horticulturally adventuresome while increasing your chances for success!

Planning Garden Stairways

Posted on July 11, 2014 by tomkarwin

My garden includes a slight slope with a few stairs, made with 8” x 8” x 48” wooden highway ties. Earlier, garden stairs might have been made with railroad ties, which were often soaked in creosote as a preservative. Today, highway ties are pressure-treated with chemical preservatives, many of which are too toxic to be used near edible plants.

Happily, my short flight of aging stairs was not treated with a preservative, but consequently it is deteriorating and needs replacement. Wood is suitable for stairs that do contact soil, but in this case I will avoid rot by using flagstones or other natural stone. There are manufactured stone-like materials that also are available for such a project.

When planning garden stairs, first determine your preferred dimensions for the risers and treads. A six-inch riser with a fifteen-inch tread is a recommended combination, but other combinations also can work well. A steep flight of stairs might have seven-inch risers and eleven-inch treads, while a gentle flight might have four-inch risers and twenty eight-inch treads. See on gardening.com for the range of other good combinations.

Then, use a straight board and a carpenter’s level to measure the change in level from the bottom to the top of the slope. For a longer slope, use a garden hose, taking advantage of the fact that water seeks it own level. Hold the hose in a U-shape, with one end near the top of the slope and the other end near the bottom. Fill the hose with water, and adjust it so water is at the opening of each end. When this condition has been met, the two ends will be at the same elevation, and the distance of the lower end to the ground, minus the distance of the upper end to the ground equals the change in level. See ongardening.com for an illustration of this method.

Divide the change in level by your preferred height for the riser to determine the number of steps needed for that particular slope.

Then, measure the horizontal distance from the bottom of the slope to the top. Your preferred dimension for the tread times the number of stairs should equal that distance. If it does not, modify the riser and tread dimensions (using one of the good combinations) or include a curve in the flight of stairs or reshape the slope.

The width of the stairs is the next design issue to be addressed. The narrowest width could be two feet, which might be sufficient for a utility stairway. A one-person stairway should be four feet wide, which is generally considered the minimum for a garden path. A two-person stairway should be five feet wide.

Wider stairways, in scale with the landscape, can provide a visually striking appearance. This stairway at Les Quatre Vents, an estate near Quebec, is designed for grand entrances. (Click to enlarge)

Staircase at Les Quatre Vents, near Quebec, Canada

Continue reading →

Gardening in July

Posted on July 6, 2014 by tomkarwin

During this hot and dry month, the avid gardener should pursue seasonal tasks to keep the garden looking good and prepare for the change of seasons.

Irrigation should be a high priority to sustain plants that must have a ration of water during the drought. Pass by Mediterranean climate plants, which are accustomed to dry summers. A little moisture will perk up even these rugged individuals and extend their best days, but a better use of scarce water resources would target the garden’s thirstier specimens.

Roses, for example, could produce another bloom cycle during July if treated to a balanced fertilizer and watered deeply. Other candidates for regular watering are plants in containers, which can dry out fast. First confirm that your water usage is within current restrictions.

If your garden consists mostly of Mediterranean climate and succulent plants, this year’s drought should not cause alarm. On the other hand, if you have a thirsty lawn, consider replacing it with plants of the summer-dry persuasion. The same strategy would be appropriate for plants from tropical, riparian or boggy areas.

Blossoms to enjoy in July include gladiolus, agapanthus and fuchsia, and fragrant Oriental hybrid lilies, e.g., pure white ‘Casablanca’.

I am also enjoying blossoms of Chitalpa tashkentensis ‘Pink Dawn’ trees, which are crosses of catalpa and desert willow. They put on a show reliably around Independence Day, but opened a little earlier this year.

The Corsican hellebores (H. argutifolius) have finished their winter-to-spring display, and leaned down their bloom stalks to drop seeds all around. The seasonal task is to cut stalks to their bases to make room for the new growth, which has already started.

The tall bearded irises also have finished blooming for this year. They will look best after the flower stalks are cut down, the leaves fade, and the rhizomes enter dormancy. Every four years, during the period from mid-July to mid-September, dig and divide the rhizomes to promote blooming for net spring.

In July and August, plant autumn-blooming blubs, e.g., autumn crocus (C. speciosus and C. sativus), meadow saffron (Colchicum autumnale), and spider lilies: Lycoris squamigera with lilac or rose pink blooms and L. radiata with orange-red blooms.

Control cool-season annual weeds, currently going to seed: bindweed, chickweed, crab grass, knotweed, lambs-quarters, mallow, pigweed, purple deadnettle, groundsel, nettle, purslane, speedwell and spurge, as well as field grasses. Dispose of seeds in the green waste not in the compost bin! The invasive cheery yellow Bermuda buttercup (Oxalis pes-caprae) has already faded, leaving clusters of bulbs to sprout next spring.