Why Plant Cover Crops?

Cover crop mix

Every drop of rain that hits bare soil is destructive. Over 3000 years ago the Chinese increased their soil’s fertility and protected it from erosion by planting cover crops. Early Nile Valley inhabitants also practiced this method of agriculture as did first century Romans. Lupines were planted in poor soil when no animal manure was to be had. Planting a cover crop is another way to improve and retain your soil.

A cover crop is really anything that covers the soil and protects it from rain, trapping nutrients and preventing them from leaching downward. Cover crops can increase the tilth of the soil. Quick germinating grasses easily loosen the top foot of soil with their root mass. Legumes have a tap root, a bio drill, that penetrates 30″ downward while alfalfa roots can grow even deeper.

Cover crops like bell beans, vetch and fava beans are especially valuable as they increase nitrogen levels in the soil in two ways. Atmospheric nitrogen can be “fixed” and left in the soil to fertilize subsequent crops. This is in addition to the nitrogen left from the foliage of the legume. Growing a cover crop also increases beneficial soil bacteria.

Cover crops are called green manure when they are chopped up and turned into the soil in spring before going to seed. The planting of legumes like peas and beans can actually increase nutrients in your soil giving you a net gain which is needed to offset what you take out of the soil when you harvest fruits, vegetables and flowers.

Late September to the end of November is the best time to sow cover crops. You will need to irrigate lightly a couple times per week if it doesn’t rain. You can also wait to sow just before the rains start. Be careful about working overly wet soil, however, as you can ruin the structure of your soil.

Orin Martin shows the extensive root system of bell beans

Recent research now recommends planting a mixture of grasses and legumes. Annual cereal grasses such as oats, rye and barley germinated quickly to hold and shield the soil until the legumes take hold. Bell beans, fava beans and vetch, which are the best legumes for our area, grow slowly the first 3 months then take off growing 70-80% in the last 3 months. The ratio of grass seed to legumes can vary from 10% to 30%.

There are other legumes that fix nitrogen but nowhere near as efficiently as bell beans. Crimson clover seed is more expensive, needs lots of water to sprout and competes poorly with weeds. Mustard causes competition with the fruit trees as bees will concentrate on the mustard flowers instead of the fruit tree flowers.

You don’t need to use innoculants on legume seed. Our soils have a native resident population of good bacteria that will break down the seed coat and encourage the plant roots to fix more nitrogen especially after cover cropping for a few years.

Work the soil lightly with a metal bow rake then broadcast 8-10 seeds per square foot. Weeds should be already cleared but this step doesn’t have to be perfect. Afterward the area should be raked again lightly 1-2 inches down and covered with 3-4 inches of straw. Wood chips would be fine, too. Mulch heavier if you have bird competition. Cover crops are vigorous and will come up through just about anything. Water in lightly.

Groundcover on Slopes

California native ceanothus goundcover

Now that we’ve had a bit of rain – and I’ll admit .37 inches is not much to write home about – it’s time to get serious about planting groundcover to protect that valuable soil on your slope.

Living ground covers add beauty to the garden while holding the soil in place and preventing erosion. They contribute to soil health by encouraging microorganisms. A garden wouldn’t thrive as well without groundcovers.

There are many attractive plants that work well for erosion control. Often they need to adapt to shallow, poor soil and cope with less than ideal conditions all while putting down dense, strong roots. California natives are among those well suited to this job.

Calycanthus occidentalis

Common native shrubs that fit the bill include ceanothus and manzanita of all types. Ceanothus maritimus, ‘Heart’s Desire’, ‘Valley Violet’ and ‘Anchor Bay’ are good groundcover that are not attractive to deer. Spicebush (calycanthus occidentalis) has fragrant flowers in late spring blooming well into summer with a spicy fragrance. The foliage is aromatic when crushed and changes from a spring green color to pale golden in autumn. Decorative woody fruits last into winter making this shrub attractive year round. It thrives with infrequent to moderate watering. Combine with coffeeberry and deer grass in sunnier spots or with Douglas iris and giant chain fern in shaded spots below trees. All these plants have deep roots and control erosion.

King Edward VII Flowering Currant

Flowering Currant (ribes sanguinem) is another show stopper capable of controlling erosion. In the spring the long, flower clusters of this deciduous shrub will dominate your garden. Choose from white flowering ‘White Icicle’ or ”Barrie Coate” and ‘King Edward VII’ with spectacular deep red flower clusters. ‘Spring Showers’ has 8 inch long pink clusters. Grow in full sun to partial shade. This California native requires little water once established and is a valuable nectar source for hummingbirds.

Some other good California native shrubs for erosion control are western redbud, mountain mahogany, western mock orange, lemonade berry, toyon, matilija poppy, western elderberry (sambucus nigra and mexicana) and baccharis.

Bush poppy

Bush poppy (dendromecon rigid) is another native found right here in our area and needs no irrigation at all once established. Beautiful bright yellow, poppy-like flowers cover the plant in spring. They can be propagated from cuttings taken in summer and are pest and disease free.

Common Snowberry or Creeping Snowberry (Symphoricarpos) will hold the soil on steep banks. This native tolerates poor soil, lower light and general neglect. Evergreen Currant (ribes viburnifolium) and creeping mahonia also tolerate shady conditions.

Smaller natives that put down deep roots are yarrow, coast aster, California fuchsia, wild grape, mimulus, buckwheat, wild rose and salvias including ‘Bees Bliss’.

Low water-use non-native ground covers like cistus salviifolius, grevillea lanigera, rosemany prostratus, rubus pentalabous, correa and sarcococcas are also good low-water choices.

Remember when setting plants on a steep slope to arrange them in staggered rows. Make an individual terrace for each plant and create a basin or low spot behind each one – not around the stem – to catch water. Set the crowns of the plants high so they won’t become saturated and rot after watering and make sure mulch does not build up around the stem.

It’s time to enjoy the fall weather and cover that ground before winter.

Autumnal Equinox

The autumnal equinox will arrive on Monday, September 23rd this year. It’s the official start of fall when the sun crosses the celestial equator and moves southward. The earth’s axis of rotation is perpendicular to the line connecting the centers of the earth and the sun on this day. Many people believe that the earth experiences 12 hours each of day and night on the equinox. However, this is not exactly the case.

During the equinox, the length is nearly equal but not entirely because the day is slightly longer in places that are further away from the equator – like where we live. Also the sun takes longer to rise and set in these locations as it does not set straight down but in a horizontal direction.

With the changing of the season, take advantage of fall planting weather. It was a hot summer and I’m ready for fall. This is the perfect time for transplanting or adding new plants to your garden. Why? Cooler air is kinder to plant foliage while soil temperatures are still warm creating an excellent environment for new root growth. In the fall many plants and trees, even broadleaf evergreens, are entering a period of dormancy. With no need to allocate resources into foliage, plants are transferring all their energy into roots and storing nutrients for the cool months ahead. By spring, the new root systems should be well established.

I had hoped to spend some time at the UCSC Arboretum earlier this year when the showy pincushion and leucospermum protea were flowering but I never made it. Because anytime’s a good time to visit the arboretum I dropped by recently. There is always something in bloom there and the hummingbirds know it. Here are just a few of the spectacular fall blooming plants that you might want to add to your own garden.

Leaucadendron Jester

The Leaucadendron ‘Jester’ (Sunshine Conebush), another type of protea, were loaded with brilliant deep wine-red bracts. This evergreen shrub grows to 5 feet tall and is very pest and disease resistant. Deer aren’t interested in the showy bright pink, cream and green foliage and it’s quite drought tolerant once established. You can cut the branches as they are prized for use in floral arrangement. People think that protea are hard to grow but really it’s a plant-it-and almost-forget-it kind of plant. They need good drainage and don’t like phosphorus fertilizer preferring poor soils with minimal care. Sounds like a winner to me.

Epilobium ‘Mattole Select’

A little further down the trail I came across another easy to care for plant. California fuchsia have undergone several name changes over the years but whether you call them epilobium or zauchneria they are in bloom now. The ‘Mattole Select’ cultivar forms tidy 6 inch high mats of beautiful silver foliage. Late summer through fall brings orangey-red tubular flowers which attract hummingbirds. Spreading by underground rhizomes, this epilobium increases size a little less vigorously than the others. It’s more shade tolerant than most California fuchsias and needs just a bit more water but it’s still quite drought tolerant. Pruning plants down to a few inches in late autumn helps rejuvenate them for the following year.

Grevillea junipera ‘Monoglo’

As I followed the hummingbirds around the arboretum I came across another groundcover that both the birds and the bees favored. Grevillea juniperina ‘Molonglo’ (Juniper Leafed Grevillea) blooms with a soft yellow flower unlike most grevillea. This fast growing evergreen forms a mass of dark green soft needle-like leaves and bears an extremely profuse show of light golden yellow flowers from late spring to winter. This tough hardy drought tolerant plants is the perfect groundcover for large areas and will cascade down slopes and walls.

I’m looking forward to another visit to the arboretum this winter as the Australian garden will be in full bloom then.

Ornamental Grasses & Grass-like Plants

Lomandra ‘Platinum Beauty’ with convolvulus trailing over side.

Looking for plants that require minimal care, only occasional grooming, just enough water to meet their needs and are deer resistant? Plants that add beauty, movement and sound to your garden? You may already have some ornamental grasses and grass-like plants but this is a good time to add a little more pizazz and beauty to your landscape.

Diseases and insect pests are rarely found on grasses They have succeeded because of their adaptability and have evolved to suit almost every environment and climate on earth. True grasses generally have extensive root systems which help control erosion. Grass-like plants such as lomandra, dianella, cordyline, carex, restio, phormium, Japanese Forest grasss and liriope are some of the best companions for interplanting with grasses. A garden just isn’t complete without the architectural qualities they provide.

Pheasant Tail Grass

There’s a reason old favorites like Karl Foerster feather reed grass is so popular in landscapes. It doesn’t get too tall or overpowering in the smaller garden and its upright habit is neat and tidy. Pheasant Tail grass is another popular grass that is carefree and long-lived. It grows to only 3 by 3 feet, is not fussy about soil and looks good anywhere you plant it. It combines beautifully with the sky blue flowers of Russian sage and is extremely drought tolerant once established.

I like variegated plants and two-tone grasses combine well with many other garden plants. Miscanthus sinensis ‘Morning Light’ is an especially refined and elegant ornamental grass. Fine leaf blades are green with clean, paper-thin, white margins that give the plant a silvery cast when viewed from a distance. It is luminous when backlit by the early morning or late afternoon sun. Morning Light tends to keep its upright shape better than some other cultivars and rarely flops. The reddish bronze plumes that appear in late fall are spectacular.

Libertia – a grass-like plant

A grass-like plant that I think should be used more often in gardens in libertia. Narrow, rigidly straight leaves form compact clumps that are especially useful i poolside, accent planting and thrive as well in containers. They require only moderate watering and can add a warm punch of color,

Dianella combined with loropetalum, pieris and primula
Dianella with loropetalum, pieris and primula

Another plant that is finding a place in the low maintenance garden is dianella. With 18 inch clumps of soft blue leaves, light blue flowers with lavender-purple fruits dianella cerulean ‘Cassa Blue’ is just one of this group of perennial flax lily that makes a great addition to the garden. Dianella intermedia grows fast with whitish blossoms during the summer months. The berries which follow are deep purple-blue and highly ornamental They can be especially attractive filling a shady nook though this plant can thrive in either su or shade.

Caring for grasses is easy. As a rule of thumb, if it browns in winter then cut it back before new growth starts. If it’s evergreen by nature just clean up outside leaves. Most like well drained soil and are tolerant of a wide range of garden conditions. You shouldn’t fertilize heavily because an excess of nitrogen can lead to lush, soft growth that tends to flop. Mulching with 2 inches of compost yearly will keep the soil and your plants in good shape. Water grasses regularly during their first year to help get a good root system established. Even grasses that are normally touted as drought-tolerant require a season or two to become fully established.

Man’s Best Friend

Sherman wishing he could be a Detection Dog

Dogs are amazing. They can do incredible things. Well maybe not my dog, Sherman, who is more likely to get into mischief than save mankind but we’ve all heard stories about detection dogs sniffing out drugs, explosives, cadavers and disaster survivors. In the mid 90’s, handlers started training them for conservation tasks such as sniffing out scat from endangered species and detecting trafficked ivory. Now their olfactory prowess is being used in the fight against invasive plants and insects.

It was my friend Cindy who told me about this latest use of detection dogs while we were walking on the beach. Her rescue dog, Sienna is obsessed with retrieving a ball thrown into the surf so she’d be the perfect candidate for a detection dog, assisting conservationists in the fight against invasive species.

Although I come across more French broom than Scotch in our area detection dogs can be trained to sniff out all invasive broom. They’re doing this in New York where Scotch broom is just starting to invade and land managers hope to eradicate it before it becomes widespread like it is here and all along the Pacific Northwest. Broom displaces native plants with thickets impenetrable to wildlife and changes the chemistry of the soil around it so that native plants can’t grow there. Broom grows quickly as it is able to fix nitrogen from the air giving a competitive advantage to other non-native weeds. It poses a serious threat to birds, butterflies and biodiversity. Broom contains a high amount of oil, which is flammable and increases the fire hazard. It’s also toxic to livestock and dogs depending on the amount ingested. And those are just some of the reasons why New York wants to keep broom away.

“Our field in the last 15 years has just exploded.” said Pete Coppolillo, executive director of the nonprofit Working Dogs for Conservation in Bozeman, Montana. The organization partners with government agencies, researchers and nonprofits on five continents to provide trained dogs and handlers for conservation projects. Besides helping to detect New York broom they have provided trained dogs to find invasive knapweed in Montana, Chinese bush clover in Iowa, yellow thistle in Colorado as well as invasive zebra and quagga mussels on boats here in California.

Working Dogs for Conservation trains shelter dogs for detection work, screening 1000 dogs for every one they put to work. To make the cut, the dogs have to be not only good sniffers and high-energy, but also seriously obsessed with toys so they’ll stay motivated to work for a reward – the chance to play with a ball.

Because I eat a lot of oranges and lemons I looked up recent papers to see if dogs were still being used to detect citrus greening disease. Sure enough what started 5 years ago with just a few dogs has increased dramatically and many dogs are now being trained. Tim Gottwald, a U.S. Dept. of Agriculture plant pathologist, said during a recent presentation in Riverside that dogs in Florida have been 99% accurate and in tests just this last December and February in Southern California backyards, they were more than 92% accurate even when distracted by the homeowners. Because dogs can actually smell the bacteria that causes greening disease within a few weeks after infection well before lab tests can confirm, their work is vitally important.

So when you’re petting “man’s best friend” tonight appreciate all the great things he does for you and for our planet.

Summer Fog & Winter Rain

Morning fog captured by redwood trees

I’m not sure how the subject changed from heirloom tomatoes to the the number of gallons of water that a redwood tree uses daily but over lunch the other day with my friend, Colly, the food writer for the Press Banner, and Susan, another friend of ours, this discussion got me thinking about the weather. Is it too early for winter precipitation predictions when the snow has barely melted in the Sierra?

Weather shapes our lives. We celebrate when the weather is good although that might mean mild and sunny for the soccer game or a rainy day when we desperately need it. We watch the Weather Channel forecast and the satellite image for what’s headed our way. Our climate is changing but it’s the seasonal weather that gets out attention.

There have been several heat waves this summer. Recently the temps soared to the high 90’s and low 100’s in some places and remained high even at night. The next couple of days brought fog so thick it dripped from the trees. We know that redwoods thrive along the coast because of the fog. Have you ever wondered how much water a tree can get from this source?

Fog drip is precipitation that forms when fog droplets condense on the needles or leaves of trees. Redwoods especially are extremely efficient producers of fog drip but other conifers like Douglas fir and pines can collect quite a bit as do large madrone leaves. According to Dr. Todd Dawson, author of “Redwood” by the National Park Service, “A relatively small 100 foot tall redwood can gather the equivalent of four inches of rain in a single evening.”

Dawson’s studies have found that Doug firs along our coast produce anywhere from 7-27 inches of fog drip each year. He measured the fog drip below a single tanoak at a whopping 59 inches of precipitation along the Northern California coast. This summer moisture can provide as much as half the water coming into a forest for over a year. Trees can absorb a small amount of water through their needles and leaves, too. A redwood tree needs about 150 gallons of water each day. Every little bit helps in our summer dry climate.

Understory native plants in a redwood fairy ring.

Because of the water that accumulates below the trees many plants like our native Western Sword fern, the small Epipactis orchid and Phantom orchid are found in these unique conditions.

Fog drip occurs every summer. Ask Mark Twain who said “The coldest winter I ever saw was the summer I spent in San Francisco”.

But what about this upcoming winter’s rainfall forecast? What’s the latest on our chances of El Nino coming to visit and bringing more nice soaking rainfall with it?

According to the National Weather Service at NOAA, “ All in all, El Nino is still present, but just barely”. Winter is still a long way off and there are many possible outcomes from the current conditions. Hopefully, we’ll be on the winning side of these forecasts. Water conservation will always be a part of our lives. Start planning now the changes you want to make in your garden this fall.

The Mountain Gardener's Weblog

%d bloggers like this: