More Interesting Than Dirt

Posted on March 23, 2015 by tomkarwin

Gardeners should refer correctly to the essence of our gardens, which is soil, and avoid calling it “dirt.”

Most soils consist of three groups of particles: sand (the largest in size), (clay (the smallest in size) and silt. The percentages of sand, clay and silt determine the texture of the soil. The best soil for gardening, called loam, has nearly equal parts of sand, silt and clay. Soil with this texture has good balance between retaining and draining moisture.

St another level, garden soil is a living environment, an ecological system, with microorganisms, decaying organic matter, earthworms and other insects. Each of these components contributes to the soil’s habitat for flora and fauna. Living soil involves a vast number of interdependent activities, which combine to create a complex and dynamic environment. These functions are enough to keep soil scientists studying for their lifetimes and motivate gardeners to at least appreciate what is going on under the surface of their gardens.

By comparison, dirt might contain a good mix of sand, silt and clay, but lacks any of the organic components of good garden soil. Dirt can be regarded as raw material for conversion to garden soil by adding organic matter (compost); this process will provide food for beneficial microorganisms and support the eventual development of the ecological system.

Dirt with a less than ideal mix of sand, silt and clay often can be improved by adding compost. Adding sand to a clayey soil, or clay to a sandy soil, might seem like a good idea, but it very difficult to create a good mix and usually results in something like concrete. Just add compost.

When we think of things that we cannot live without, many people will list sunlight, air and water, but not include soil, which is the essential fourth contributor to life on earth.

With this in mind, soil scientists from around the world have joined to name 2015 as the International Year of Soils, with the goals to educate the public about the importance of healthy soils. The Global Soils Partnership, which includes the United Nations’ Food and Agriculture Organization <http://www.fao.org/soils-2015/en/>, The Soil Science Society of America <www.soils.org/iys>, and many other groups, is spearheading these efforts. We are pleased to support this educational initiative.

The Partnership has identified a theme for the educational activities of each month during 2015. The theme for April is “Soils Clean and Capture Water,” which is timely during California’s current severe drought conditions. As a group, the monthly themes provide an overview of the many ways in which soils support the quality of life on Plant Earth.

January – Soils Sustain Life
July – Soils are Living
February – Soils Support Urban Life
August – Soils Support Health
March – Soils Support Agriculture
September – Soils Protect the Natural Environment
April – Soils Clean and Capture Water
October – Soils and the Products We Use
May – Soils Support Buildings/Infrastructure
November – Soils and Climate
June – Soils Support Recreation
December – Soils, Culture, and People

Each gardener can support the International Year of Soils, in these ways:

Visit the websites listed above, which include many ideas and resources for teachers:
Read a good book on soils. Good options (all available on Amazon.com) include:
Discontinue any uses of synthetic chemical fertilizers or pesticides in your garden.
Annually, add a layer of compost to your garden beds. (Right now would be a good time.)

All plants respond to good soil!

Rain at Last

Posted on December 14, 2014 by tomkarwin

As an impressionistic meteorologist, I’m very pleased with our recent rains and even more so with the promise of more rain in the near future. Some areas of northern and central California could actually reach normal levels of annual precipitation. The Santa Cruz area is during fairly well, but this happy future might not extend throughout the area: portions of Monterey County are receiving lighter precipitation.

: Storm runoff, San Carlos /Beach Parkphoto by Vern Fisher, Monterey Herald

What have we learned?

My first reaction to the overdue rain is that we can now anticipate fresh new stems and leaves and a great floral display in the spring. Our plants are responding to the moisture by extending their roots and drawing in nutrients, preparing for a new season of growth.

Then, I flashed on the idea that the drought is over for good, and we’re back to the Monterey Bay area’s historical weather pattern, with a dry summer and the onset of the rainy season around mid-October. This thought didn’t last long. Realistically, our climate is changing in ways that will change our gardening—and our lives—in significant ways.

This change is happening at a fast rate, not with the very slow arrival of the Ice Age (approximately 110,000 to 12,000 years ago or the Little Ice Age (1550 to 1850), which developed relatively more quickly, over a period of about 200 years.

Politicians are debating a range of responses to today’s emerging problem. Clearly this is a global issue that requires global action, but as individuals, we can respond in small ways. The most constructive action for individuals is to elect those who accept the reality of climate change and support long-term solutions.

As gardeners, we can pursue three basic strategies:

First, retire plants that require summer irrigation and that suffer under drought conditions. The single most widespread plant in this category is lawn grass, which achieves it aesthetic potential only with frequent irrigation, applications of nitrogen fertilizers and broadleaf herbicides, and regular cultivation, including mowing, aeration and pest control.

In a future column, I will describe alternatives to traditional turf grasses.

Tropical-climate plants compirse another category to avoid for drought-tolerant gardens. Examples include the hibiscus (H. syriacus is the most popular ornamental species) and the banana (Musa acuminata, M. balbisiana and others). In general, avoid plants with large glossy dark leaves, which tend to absorb more heat, require a lot of water and transpire a lot of water.

For the water needs of specific plants, Sunset’s Western Garden Book provides useful guidelines, with briefly descriptive terms from “ample water” to “little to moderate water.”

The second basic strategy is to favor plants that will survive in your garden under drought conditions. Generally, as often mentioned in the column, these are plants that are native to coastal California and other Mediterranean (or “summer-dry”) climates. These plants will do better with a little moisture during a prolonged drought, but they have evolved to withstand dry periods, using such methods as growing small leaves, that minimize water loss.

Succulents are another category of drought-tolerant plants, which have developed structures for storing water in their leaves, stems or roots.

The third strategy for drought-tolerant gardening is to use water wisely, through drip irrigation and regular mulching. These water-conservation methods complement the two preceding strategies for plant selection, and help the gardener to cope with water restrictions.

Use the next clear days to assess your garden for drought-tolerance. However much we enjoy the current rains, preparing for future droughts requires long-term planning..

Time to Plant Your Garden

Posted on September 30, 2014 by tomkarwin

Over the next few weeks, as we move into autumn, it is time to think about installing new plants in our gardens, and moving plants that should be in better places.

Installing or moving plants makes sense during this time of the year for two reasons. First, many plants that are good choices for Monterey Bay area gardens are entering into a dormant period, during which they can be moved with minimal trauma from one garden location to another, or from a nursery pot to a larger container or into the ground.

The second rationale for installing or moving plants now is that our familiar rainy season, beginning usually mid-October, will irrigate them during dormancy. The gentle rains of fall and winter have been a welcome gift to gardeners, who can attend to other tasks as plants develop their roots and generate new growth for the spring, as temperatures warm.

We still do not know if we will have a normal rainy season this year. Recent reports from International Research Institute for Climate and Society and the Climate Prediction Center, both trackers of the El Nino/Southern Oscillation, indicate a relatively small impact on our fall and winter weather, around 60 to 65% of the historical norm. In other words, we should expect rain, but not as much as we usually enjoy.

That forecast is more vague than gardeners would like, but now is still the time to plant. The worst-case scenario is that watering by hand or drip irrigation might be needed to keep newly installed plants adequately hydrated.

Gardeners might be inspired to bring new plants to their gardens in the spring, when garden centers are displaying plants in bloom. There are real advantages of planting in the spring: bedding plants are available in abundance, blossom colors are evident, and the weather welcomes outdoor projects. One downside of this schedule, however, is that customers pay for nurseries to care for the plants during their early growth. Also, plants that have been boosted into bloom with synthetic fertilizers often under-perform once they have been moved into typical garden soil.

When you bring new plants into your garden this autumn, choose plants that are drought tolerant and well suited for the local climate and growing conditions. Such plants are most likely to succeed under drought conditions with the only basic care by the gardener.

Remember: even drought-tolerant plants need water, just not as much and not as often.

Good opportunities soon will be available to find such suitable plants:

Succulent Extravaganza, September 26 & 27 (today and tomorrow); 2133 Elkhorn Road, Castroville. Info: sgplants.com, 831-632-0482.
Fall Plant Sale, UC Berkeley Botanical Garden, September 28; 200 Centennial Drive, Berkeley. Info: botanicalgarden.berkeley.edu, 510-643-2755.
Fall Plant Sale, UC Santa Cruz Arboretum & California Native Plant Society, October 11; High Street at Western Drive, Santa Cruz. Info: arboretum.ucsc.edu.
Fall Show & Sale, Monterey Bay Area Cactus & Succulent Society, October 18 & 19, 10 San Jose Street, San Juan Batista. Info: www.facebook.com/MonteryBayAreaCactusAndSucculentSociety

Gardening success depends on the selection of plants that are appropriate for specific locations and growing conditions. You might change where you garden, but external forces could change your garden’s growing conditions. Plan ahead!

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.

Click to Enlarge

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.

Click to Enlarge

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.

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.

Spring is Here

Posted on March 22, 2014 by tomkarwin

This year’s puzzling weather has produced a few days cold enough to promote dormancy in plants that don’t need a real winter chill, and nowhere near enough rain. We still hope late rains will replenish aquifers and reservoirs, but there’s little promise in the forecasts.

The arrival of spring does not cause abrupt change in our gardens, but it does bring warm weather that takes plants out of dormancy and stimulates new growth. Plants need moisture at this time but water restrictions demand reduction of our water usage. The middle ground for gardeners involves watering plants efficiently and only when they show need by wilting a little. This means drip irrigation if you have it, or moving a hose or watering can from plant to plant. Store your wasteful wide-area sprinkler!

If you have been preparing for drought conditions, you have emphasized summer–dry plants, a category that includes California native plants and other Mediterranean climate plants.

This is not the best year to add summer-dry plants, however: newly installed herbaceous or woody plants need regular watering for two years to establish roots.

A more appropriate strategic response to this drought is to add succulent plants, which have developed ways to minimize transpiration and maximize water retention in their leaves, stems or roots.

When added to a garden or moved within a garden, succulent plants come with their own supply of moisture, and need only minimal watering to settle their roots. They are quite resilient, but of course will need some water in time.

Succulents are far from compromises from an aesthetic perspective: they offer a range of blossom colors and foliage textures as well as low maintenance and drought tolerance. They have in fact become desirable specimens in garden beds or containers, even before our current weather concerns.

Happily, a major sale of succulent plants is less than one month away. The Monterey Bay Area Cactus and Succulent Society will hold its annual, free-admission Spring Show & Sale from 9:00 to 5:00 on April 19^th and 20^th in the San Juan Batista Community Hall, 10 San Jose Street, not far from the Old San Juan Batista Mission.

The Society’s show will include members’ selected cacti and succulents, demonstrating plants that are very well grown and shown, and that display an amazing range of shapes, sizes and colors. The sale includes a great selection of mostly small plants grown by members or commercial growers, with reasonable prices. Society members also will be available to offer advice and answer questions.

Respond to this drought creatively: use this occasion to start or expand your collection of succulent plants.

If you are a beginning gardener of succulent plants, a helpful book is Debra Lee Baldwin’s newest book, Succulents Simplified. Her earlier books, Designing with Succulents and Succulent Container Gardens, are a more advanced, but still accessible for casual gardeners.

Visit Debra Lee Baldwin’s website for inspiring photos and practical information.

Dry-Weather Gardening

Posted on January 25, 2014 by tomkarwin

Local weather patterns have been quite unusual, recently.

The Monterey Bay area had a short spell of cold, relative to our familiar moderate temperatures, followed by very dry and warm days. Now, much of central California is officially in “extreme drought,” and likely to remain in that condition for the next several weeks.

The National Weather Service has blamed the recent weather on “a strong ridge of high pressure in control along the west coast,” and on January 21^streported “all signs point to the ridge off the coast rebuilding for next week…this will lead to more above normal temperatures (more records will likely be set) with all of the rain staying to the north. Long range is trending more pessimistic for rain chances out to February 7^th…Unless there is a big shift in the pattern, this will go down as the driest January on record for almost all locations.”

The University of California’s Agriculture and Natural Resources specialists have recommended strategies for keeping edible and ornamental plants alive during this drought.

First, watch plants for signs of water-stress. The symptoms include

wilting or drooping leaves,
curled or yellowed leaves that fold or drop,
foliage that changes form green to grayish,
new leaves that are smaller than normal,
lawns that retain a footprint longer than usual.

Ornamental trees are generally in a dormant stage, at this time of the year, and will not require watering until they resume growth. One or two deep irrigations in the spring and summer will keep them healthy and resistant to diseases and insects.

Fruit and nut trees will require adequate moisture from bloom until harvest to produce a good crop. If that level of irrigation is not available, a few early-season irrigations will keep the trees alive, at least, although they might not produce much fruit.

Shrubs will need a thorough watering in the spring, and one or two more summer irrigations to be kept alive.

Most vegetables will need regular irrigation during flowering and fruit production. Squash, zucchini and other vines can be kept alive with irrigation once or twice weekly through the season.

Ground covers should be watered about monthly from April through September, with amounts related to local heat and dryness.

Lawns should be provided at least half the usual amount of water. Without adequate moisture lawns will go dormant eventually, but often can be revised with subsequent watering. Warm-season lawns (e.g., Bermudagrass, buffalo grass) are more drought-tolerant than cool-season lawns (e.g., tall fescue, ryegrass).

For now we can only wish for the overdue rain and water our plants at least minimally.

For the most up-to-date, authoritative information on local weather, click here to visit the website of the Western Region Headquarters of the National Weather Service. Click on “San Francisco Bay Area” for information that is closest to the Monterey Bay Area.

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Tag Archives: Drought