The Ageless Aeonium

Today, we introduce the genus Aeonium, which includes 35 species, most of which are from the Canary Islands, northeast of Africa.

These plants are characterized by the development of rosettes of leaves on basal stems, i.e., stems that rise from the plant’s roots.

The generic name, Aeonium, comes from an ancient Greek word that means “ageless.” In fact, for most species, the rosettes die after producing a flower, although the entire plant lives. A few species are monocarpic, meaning that they produce a single rosette without a stem, and then the entire plant dies.

Popular Cultivars

  1. A. ‘Zwartcop’ (Black Rose), a cultivar of A. arboretum, develops rosettes with very dark reddish-purple, almost black leaves, on stems that can rise to four feet. This plant produces effective displays in the landscape or in a mixed container, especially when contrasted with yellow flowers like those of the plant’s own blossoms.
  2. A. ‘Sunburst’ (Copper Pinwheel), a cultivar of A. davidbramwellii, is a variegated form, with large rosettes with variegated green and white leaves edged in bright, coppery red. The stalks rise up to 18 inches. ‘Sunburst’, like other variegated plants, can provide pleasing contrast in the garden.

Aeonium 'Sunburst' best

  1. 3. A. nobile (Noble Aeonium) produces a single, stemless rosette up to nearly two feet in diameter, making it entirely distinctive among the aeoniums. The leaves are yellowish, with a reddish edge when grown in bright light. This is one of the monocarpic aeoniums: it dies after producing its reddish blossoms.
  2. A. tabuliforme (Saucer Plant, Dinner Plate Plant) is another monocarpic aeonium that provides a single, unique, nearly flat stemless rosette.

Cultivation

Aeoniums will be dormant during the summer months and resume growing in the early autumn.

They are very easy to grow in containers, where they flourish with their shallow roots and occasional watering. Use a normal potting soil, rather than a fast-draining cactus mix. In the Monterey Bay area, they prefer bright morning sun and afternoon shade. Fertilize only when the leaves become yellowish, indicating nitrogen deficiency. Too much fertilizer will promote too-rapid growth and weak stems.

When grown in the garden in this area, aeoniums require little care. As with container plants, avoid very rich soil and fertilizers.

Propagation

All aeonium species and hybrids can be propagated from seeds, but most are propagated easily from stem cuttings. This might be done to produce additional plants or to bring a rangy plant into a more compact form. During the plant’s normal growth period, from autumn to mid-spring, cut a rosette with up to five inches of stem (shorter for smaller, shrub-like forms) and place in a cool shady place for at least three days, to heal over. Then, place the cutting in a normal potting mix, in a small container, and in a shaded, windless location to reduce moisture loss. After the plant has established roots, place in a container or in the garden.

The monocarpic species are not propagated from stem cuttings, but from leaf cuttings, which are more successful with A. tabuliforme than with A. nobilis.

Aeoniums are drought-tolerant plants that are easy to cultivate and interesting additions to the garden.

Restoring Soil

Several people commented on last week’s column on the carbon cycle. All endorsed the concept of restoring garden soil, to support its natural ability to sequester carbon.

One reader had questions about how to go about restoring garden soil. This is a Big Topic and you, good reader, might have your own questions, but you also might share his interests. My brief responses are below. Visit gardening.com for more details, including plant suggestions.

Q. Plow the grass under?

A. Losing the thirsty lawn is a good first step, because such monocultures are not appealing to wildlife. Plowing, however, could both promote re-growth of the grass and bring dormant weed seeds to the surface. A better approach is to kill the grass over several sunny weeks by covering it with clear plastic (solarization), or with newspaper or cardboard (smothering).

For information on Soil Solarization for Gardens & Landscapes, visit the University of California’s Integrated Pest Management webpage on the topic. The presentation emphasizes pest control; in this context, unwanted turf grass amounts to a pest.

The California Native Plant Society has Detailed lawn removal advice.

Q. Plant different grass?

A. Yes! California native grasses can provide the basis of an attractive meadow, which is more casual than a manicured carpet of turf grass. A meadow has unique aesthetic appeal; supports a variety of wildflowers and wildlife; requires little water, infrequent mowing, and no chemicals; and helps to restore the soil.

Kids on Native Grass Lawn
JACQUELINE RAMSEYER —
BAY AREA NEWS GROUP

Lily Baker’s front yard in San Jose
features a native grass lawn.
California native grasses help restore the soil.

For information on several California native grasses, visit the Tree of Life Nursery’s web page, “Masses of Grasses.”

A very good book by Carol Bornstein, David Fross, and Bart O’Brien is Reimagining the California Lawn: Water-conserving Plants, Practices, and Designs (2011).

Q. Grow more trees?

A. Absolutely! Trees and large shrubs are attractive additions to the landscape, valuable participants in the carbon cycle, and welcomed by all forms of wildlife. Invest a little research to select trees will thrive in your climate, and grow to an appropriate size for your landscape. Again, California natives are good choices.

A good introduction to California native trees and larger shrubs is available from the non-profit Nipomo Native Garden, which has produced a web page, “Native Trees for Landscaping and Wildlife.”

Q. Eliminate ground cover in favor of something with deeper roots?

A. Ground covers are any plants that hug surface or rise to any height up to four feet. Most importantly, they protect soil and soil microbiota from baking in the sun, or eroding. During the fall and winter, plant seasonal cover crops that draw nitrogen from the air and store it in their roots. Examples of such “nitrogen-fixing” plants include peas, beans, and clover. In the spring, before your cover crop sets seed, till the plants under to decompose and release their nitrogen into the soil to support the growth of other plants.

Deeper roots mean better drought-tolerance: deep-rooted plant can find moisture far below the surface. Such plants are generally preferable in the landscape, all other factors being equal.

The depth of roots varies among plants, reflecting adaptation to the plant’s environment. Among weedy grasses, for example, Annual Bluegrass (Poa annua) has roots only about right inches deep, while Bermudagrass (Cynodon dactylon) can grow to 60 inches deep in search of water.

Infrequent, deep irrigation encourages all plants to develop deep roots and drought tolerance. A common error with automatic irrigation systems is to schedule frequent, brief periods of watering. This practice encourages shallow roots, ultimately increases overall water usage and leaves plants vulnerable to dry periods.

Q. Shallower roots?

A. The advantage of shallower roots is that plants growing in arid climates have immediate access to occasional rains. Succulent plants have adapted to such conditions by developing shallow roots and the ability to store scarce moisture in their leaves, stems or roots. For this reason, gardeners often appreciate succulent plants for both drought tolerance and landscape appeal.

The New California Garden, which we envision here, features meadow grasses and succulent plants: a good time to start is now.

Bare Root Trees and Shrubs

One of the best bargains in gardening is planting bare root trees and shrubs. And now is the time to do just that.

Bare root trees are dormant, by definition, and not attractive in the usual way, but they are excellent candidates for addition to your garden.

Bare Root Tree

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I have often written of the advantages of buying mail order plants, to draw from a wider selection than local garden centers can offer. That’s still a good practice for many plants, although there are drawbacks, as well: mail order buyers need to confirm that the plant of interest is right for their garden, particularly in terms of winter temperatures. Some tropical plants will not survive even the moderate winters of the Monterey Bay area, and some require more winter chill than they will receive in our climate, and will not blossom or fruit well here.

Years ago, eager to start a small orchard of antique varieties of apple and pear trees, I ordered ten bare root plants from a mid-west nursery, only to watch them struggle and eventually fail for lack of winter chill. Purely by chance, one tree, a Cox’s Orange Pippin, managed to survive my garden’s USDA zone and is producing very tasty apples to this year. That tree stands to remind me to do my homework before ordering mail order plants.

The hazards of selection are less important during bare root season because local garden centers are able to stock very good inventories of bare root trees and shrubs that are right for the local climate.

Despite the best efforts of garden centers, the economics of stocking containerized plants limit inventories of plants in pots: they cost more to ship and require more space, and offered at twice the price of the same plant in bare root.

Conversely, mail order suppliers (which still might offer a greater range of choices) can ship wholesale orders of bare root plants efficiently to garden centers, but have to recover the greater costs of shipping small quantities of plants to retail purchasers. So, for individual gardeners, the mail order price could be higher than the garden center price.

Additional benefits of buying bare root plants include larger root mass, according to researchers, easier to move and plant without soil and container, and faster growth because they adapt easily to local soil as they come out of dormancy.

The range of options at a garden center could include ornamentals, fruit trees, roses and berries. Many other shrubs could be offered in bare root form, as well, with the same advantages, but I have seen little development of that market.

When selecting an ornamental or fruit tree, look for a straight trunk, evenly spaced branches (if any), good spread of healthy-looking roots that have been kept moist, and a complete lack of any wounds or disease.

Many garden centers also offer espaliered fruit trees that have been developed by grafting branches in the right places, rather than by the time- and labor-consuming process of training. Some espaliered dwarf apple trees include grafts of several apple varieties, to produce a healthy young tree that will both fit a tight space in the garden and produce a selection of applies that ripen at different times during the season.

It is important to plant bare root specimens before bud break, so there is a small window of opportunity for the lowest prices. Don’t delay!

Shrub Selection

Q. I love your column and appreciate that you invite questions.  I want to grow a thick but attractive shrub on the shady side of my house.  It receives very little sun there and is somewhat damp.  Do you have any suggestions?

I live between Fremont and Del Monte off of Montecito in Monterey, if that gives you an idea of the weather.

I like tea trees and they do well in my front yard, but there’s more sun there.  A friend recommended Dodonea, which I’m not thrilled with, but it would be okay.  I don’t know about Abutalon, it might need more sun.

If you could suggest something, I would be most grateful.

A. The Dodonaea is an interesting option, but it’s a tropical plant that appreciates more sun than you seem to have in this spot. Here’s a link to a description of the Purple-leafed Hop-Bush, from San Marcos Growers:

The Abutilon also prefers full sun. It’s attractive but may be more open in structure than you are looking for.

I prefer to recommend California native plants, as you might already know. A very good California native shrub is the Ceanothus (California Lilac), which would do well in your garden. I have a list of over twenty Ceanothus species that are shade tolerant. I could narrow down that list to a few options for your situation, based on the mature size that you would want for a plant in this location.

Let me know what height and width you have in mind for this plant.

Q. Wow!  You’re wonderful!  Thank you so much!  I agree that natives are the best, but I forget that.  Not quite there yet.  The ideal height would be around 7 feet tall.  It would be along a fence, so the width of the area I want to cover would be about 30 feet.

In my rush, I had forgotten to check what the Ceanothus looked like.  Of course, having grown up on the Peninsula, I am very familiar with it.  It’s flower is soapy, as I recall from having smashed them as a child.  This is a beautiful plant, full of color!  I love it!   With the dimensions that I gave you, do you think it would work, where would you recommend I buy it, and do you ever recommend gardeners?  Thank you!

A.

I reviewed the lists of such shrubs in a couple reference books, and searched through the inventories of some likely sources: San Marcos Growers, Suncrest Nursery, Las Pilitas Nursery and Yerba Buena Nursery. They all list several Ceanothus plants, but most are sun-loving, and the shade tolerant varieties tend to be low-growing. The remaining candidates might or might not be in stock at present.

So, on a recent visit to Native Revival Nursery, I found two varieties of Ceanothus thrysiflorus that might meet your needs. Both are listed as being shade-tolerant and capable of growing to 10 feet. When grown in partial shade, I would expect that they would not reach their maximum height, but would top out closer to the seven feet you have targeted.

These plants are in stock  at Native Revival Nursery (2600 Mar Vista Drive, Aptos).

They have both varieties in 5-gallon size for $24.99 each. The Snow Flurry is also available in 1-gallon size, for $9.99.

Blue Blossom grows to six feet wide, so for a 30-foot screen you would need five plants.

Snow Flurry grows to 8-12 feet wide (perhaps 8-9 feet wide in the partial shade), so you would need four plants.

You could mix the blossom colors, too!

Best wishes. I hope this helps.

Q. What a wonderful resource you are!  Thank you for these ideas and attachments.  I have written to the nursery and let them know that I’d like to buy three Blue Blossom and two Snow Flurry.  Thank you so much for your help!

Back to the Future Garden (Bulbs)

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).

Spring Bulbs

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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.

Yellow Foxtail Lily

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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 19th 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.

More

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.

Gardening with Exotics

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. Giant White SquillClick to Enlarge Giant White Squill - CU 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.

More

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!

Gardening in July

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’.

Casablanca Lily

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.

IMG_0291

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.

Behind Schedule in the Garden

The garden does not wait for the gardener, but goes about growing, reproducing, aging and eventually dying whether or not the gardener meets the schedule of seasonal tasks.

My garden has proceeded this year on its natural cycle. As the weather has warmed, even the plants for which I should have cut back last year’s growth are producing abundant new growth

Salvias exemplify this failing. Best practice with salvias is to cut them to the ground in the late winter or very early spring, when new growth first appears. This practice rejuvenates the plant, and gives it a youthful look. When the pruning is done too late, it is very difficult to avoid cutting off the new growth and setting back the seasonal growth.

I cut back a few of the salvias in my garden, but left many more with their tired branches from last year.

Fortunately, perennial plants really do not depend on punctual gardeners. Salvias perform better when treated well, of course, but they will survive nicely even when neglected.

I was able to prune my roses at the right time. It is possible to let rose shrubs grow without annual pruning during the dormant season, but they will have a more compact form and produce more blossoms when cut back about one-third each year.

Fruit trees are another matter. Happily, I pruned my apple trees in a timely way: I cut back last year’s growth just before blossoms appeared on the trees. There are just four dwarf apple trees in my garden, but skipping this annual task would allow sprawling growth and reduce the yield.

I did not, however, spray my trees as recommended to discourage codling moths. I did read about the life cycle of those pests, and made life a little harder for the over-wintering larvae by raking the mulch away from the base of the trees.

Weeds also are responding well to our limited rain and the warming weather. They are growing very nicely! I haven’t identified all the several weeds that make my garden their home, but I can always spot the bright yellow flowers of sourgrass, which expands its territory in my garden each year.

Wikipedia (always helpful) has this comment about sourgrass: “Indigenous to South Africa, Oxalis pes-caprae, the ‘Bermuda buttercup,’ is an invasive species and noxious weed in many other parts of the world, including the United States (particularly coastal California)…”

Ideally, gardeners should pull this weed when it first appears, before it produces countless tiny bulbs. Sadly, I am behind schedule again this year.

This experience yields clear lessons for gardeners:

  • Strive to keep pace with Nature’s rhythm
  • Appreciate the ability of plants to thrive despite neglect, and
  • Take satisfaction in the seasonal tasks you do complete.

Enjoy your garden!

More

Several books on year-round gardening are available through your public library, your bookstore or online. For example, a search of the Amazon.co website for “gardening year-round” yields 45 pages of books to consider. Many of the books listed focus on edible gardening; several also include ornamental gardening.

Before investing your time or money in a gardening book, make sure that it has information for your gardening environment. The most useful gardening information for gardeners in the Monterey Bay area will be specific to USDA Plant Hardiness Zone 9. Information in books oriented to “northern California” or “Pacific Northwest” will need interpretation for gardeners in Zone 9. Books intended for other parts of the United States or the world could still be helpful, but should be treated like exotic materials.

Still, given that awareness, some classic books on year-round gardening written by English authors can be very much worth reading. Examples, include books by Vita Sackville-West, Beth Chatto and Christopher Lloyd.

Whether written by American or English gardening experts, the date of publication is not important: Nature’s seasonal patterns have not changed significantly.

Here are suggestions:

The Four-Season Landscape: Easy-Care Plants and Plans for Year-Round Color (A Rodale Garden Book) (1994), by Susan A. Roth (Author)

Golden Gate Gardening, 3rd Edition: The Complete Guide to Year-Round Food Gardening in the San Francisco Bay Area & Coastal California (2010), by Pamela Peirce (Author)

Gardener to Gardener: Almanac & Pest-Control Primer (2000), by Vicki Mattern and Fern Marshal Bradley (Eds)

A Yardscapes Year: Ideas and Plants for Bay Area Gardeners (1999), by Mia Amato

The Western Gardener’s Journal: A Three-Year Almanac (1998), by Margaret Moulton

Some Garden Thugs You Want Around

A weed is simply a plant growing in the wrong place, while a garden thug is a plant spreading without apparent limit, and overwhelming other plants it encounters. Garden thugs could well be landscape assets, given freedom to expand. Here are three examples from my South African succulent bed.

Thug #1: Aloe maculata (Soap Aloe)

Aloe-maculata-Soap-Aloe

Some 550 recognized species are included in the genus Aloe. One of them, the Soap Aloe (its sap makes a soapy lather in water) is among the most popular Aloe species in California gardens. The plant forms a rosette about a foot wide, made of pointed fleshy leaves about eight inches long. In the spring it sends up a two-foot long stalk topped by orange-red flowers in a flat-topped cluster called a raceme. So far, so good, but it also sends underground suckers that soon create a dense colony. I lifted ten plants for this month’s garden exchange, then put another eight in the green waste.

Related species in my garden include A. arborescens (Torch Aloe), also a vigorous grower; A. plicatilis (Fan Aloe), a slow-growing small tree; and A. ‘Christmas Carol’  (hybrid), a smaller plant with vibrant red colors in the leaves. In this group, Soap Aloe is the real thug.

Thug #2: Senecio mandraliscae (Blue Finger)

Senecio mandraliscae

Senecio is one of the largest genera of flowering plants, with about 1,250 species that present many amazing forms. Blue Finger, which might be a hybrid, grows twelve-to-eighteen inches tall, with numerous four-inch long blue-gray leaves shaped like fat bean pods. It produces uninteresting white flowers in summer but the foliage is the main attraction. The leaves will drop easily from the plant, and root to form new plants. The spreading stems also quickly establish roots.

A nice-looking succulent plant and a welcome addition to the garden, but one that needs regular whacking to keep it within bounds. My other Senecios are S. rowleyanus (String-of-Pearls) (showing the variability of this genus) and S. haworthii (Wooly Senecio). There could be other thugs in this large genus, but Blue Finger certainly qualifies.

Thug #3: Cotyledon orbiculata (Pig’s Ear, Paddle Plant)

Cotyledon-LSCotyledon-CU

This striking succulent has gray-green fleshy leaves with red margins, and coral red, bell-shaped flowers on stalks in early spring. The leaves grow on stout branches growing any way other than straight. This attractive plant spreads over time, and is considered invasive in some parts of the world. The plant has medicinal uses, but its leaves are said to be toxic to livestock, poultry and dogs. It works well in containers, which might well be the best place for this plant.

These vigorous plants will prove you have a green thumb, but they require control.

Selecting a Landscape Tree

“The best time to plant a tree is twenty years ago. The second-best time is now.”

This is one of many hoary bits of wisdom about gardening. Instead of reviewing more such bits, let’s consider how to select a landscape tree during this year’s dormant period.

The New Sunset Western Garden Book (2012)—always a useful reference—lists four categories of garden trees that not yield edible fruits: patio, shade, flowering and fall foliage.

Patio trees are primarily ornamental, and relatively small and free of troublesome behavior.  Shade trees are larger than patio trees, and typically deciduous. Flowering trees and fall foliage trees also provide shade, but they are selected primarily for their ornamental value.

Landscape trees, depending on size, could be dug as bare root specimens, grown in a plastic container wooden box, or dug and “balled & burlapped.” The larger specimens can be expensive and very heavy to manage, but desirable for achieving an immediate effect in the garden.

Once the gardener has decided on the landscape purpose of the tree and its size at the time of purchase, there are three major criteria for selecting a specific tree.

First, know the tree’s mature size and ensure that it will not outgrow the location you have in mind. The most common error in selecting and planting a tree is to locate it where it eventually will grow to become unwelcome. It might crowd a pathway or driveway, or even the residence. Its might harm other plants by blocking the sunlight with its leaves or absorbing the available moisture with its roots. Choose a tree that will be a good neighbor.

Second, for containerized trees, confirm that the roots have had ample room to grow normally. A tree’s roots should fill no more than 50% of the container; otherwise, the tree could become root-bound, with a long-term threat to its life. I once had a tree service install a large Santa Cruz Cypress (Cupressus abramsiana), an endangered species, only to have it topple months later during a mild windstorm. I discovered that it was severely root-bound, so that its roots could not anchor the tree effectively. Before buying a tree, examine its root structure by pulling the tree from its container.

Thirdly, ensure that the tree’s future location has at least six hours per day of exposure to sunlight, which almost all trees require for health and normal growth. I planted two identical Chilean Myrtle (Luma apiculata) trees, one in full sun, and one too close to an American Sycamore (Platanus occidentalis). Today, the tree growing in the sun is about three times the height of the other tree.

Choose your new landscape tree with care!

More

The April 2014 issue of Fine Gardening magazine (already on the newsstands and in libraries!) includes an excellent article on this topic. “How to Buy a Tree” by Ed Gregan presents a most thorough discussion of problems that might be encountered with a nursery tree.

I hasten to add that reputable nurseries and garden centers won’t offer trees with significant shortcomings. The owners and managers of well-run retail garden outlets are good people who respect plants and gardening.

Still, it’s possible for a problem to slip through and you could take home a tree that won’t thrive as you, the original grower and the tree itself would prefer. The most common problem is a tree that has become root-bound, after sitting in the garden center or nursery too long. This condition obviously could develop while the manager was not looking!

Ed Gregan’s article is not available online (except for Fine Gardening subscribers), so I can only list his bullet points (below), but you’ll need to read the article for the full story.

  1. Ensure grant points are smaller than a dime
  2. Walk away if there are wounds
  3. Pull off the pot to assess the roots
  4. Strive for a single straight leader
  5. Check under the trunk protector
  6. Look for signs of trouble
  7. Watch out for “coat hangers”
  8. Avoid poor crotches
  9. Avoid even numbers for multistems
  10. If the flare is too high or too low, the tree is a no
  11. Give the ball a thorough inspection
  12. Check for even spacing with clumps