Growing Cover Crops – Part II


Orin_Martin_bell_beansOrin Martin of the Alan Chadwick Garden on the UCSC campus is widely admired for his incredible knowledge and skills as a master orchardist, horticulturalist and teacher. I was lucky a couple of years ago when he visited a group of fellow designers and brought his favorite russet apples. Another time he brought a dozen different kinds of potatoes that we roasted, critiqued and thoroughly enjoyed.

The Alan Chadwick Garden was nothing but poison oak and chaparral in 1967 when Alan Chadwick first got his hands on it. Martin came to UCSC in 1969 as a literature major but was soon impressed with Chadwick’s work, preaching the gospel of treating the garden as a self-nourishing system. Together they worked the garden, building the soil and teaching others.

Now Martin runs the appreaster_Michaelmas_daisy.2048ntice program which teaches future organic gardeners and shares his knowledge in workshops like the Cover Crop class I recently attended.

Last week I wrote about how and why to plant cover crops. This is what to do next spring after they’ve done their magic in the soil fixing nitrogen.

Cover crops are plowed or skimmed off in late February to early April. Because it takes 3-5 weeks for the cover crop to break down so crops can be seeded or transplanted, it is often best to skim off the cover crop at the base of the plants and combine with straw or leaves to make compost. Previously made compost can then be applied to the surface. It is important to retain the roots and nitrogen-filled nodules in the soil. Take only the vegetative portion.

cover_crops_Orin_Martin.1280Another method is to skim the foliage with a weed wacker or mower chopping it into small pieces 1/4″ to  4″ long. You can then rototill this into the soil and allow it to decompose on its own. In about 2 weeks the material should be broken down to be unrecognizable as plant material before replanting.

If you are developing your soil to build organic matter and improve structure incorporate the cover crop at a more mature stage (half to full bloom) when it has a higher carbon content. The nutrients will be stored in the reservoir of humus and released slowly over a number of years.

On established soils where you want primarily to fertilize next spring and summers crops, incorporate the cover crop after skimming and chopping when it has just started to flower as it decomposes quickly at this stage.

The Chadwick Garden fertilizes its established fruit trees by simply cutting down the cover crop growing at their base with a machete at the 25% flowering stage. 4-6″ of wood chips are laid over the chopped up pieces and left for nature to decompose. That’s all their is to it. Martin explained that the garden used blood meal and the organic fertilizer, Sustane, during the first several years while the trees were becoming established.

Picking up a clump of grass sown just 2 weeks ago, Martin teased off the soil to show the vigorous, fibrous root mass. “This is why the riches soils of the world, the Steppes of Russia and the original Midwest prairies, are so fertile and are called bread basket soils”, he explained.

Plant a cover crop this fall and your soil will be richer for it.



Growing Cover Crops- Part I


Every drop of rain that hits bare soil is destructive. Over 3000 years ago the Chinese knew how to protect their soil from erosion and increase fertility by planting cover crops. Early Nile Valley inhabitants 3500 years ago 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. I learned this and also how to protect and improve my soil from Orin Martin, manager of the Alan Chadwick Garden at a cover crop workshop recently on the campus.

aster_Michaelmas_daisy.2048“It’s all about the biology of the soil”, Martin said. “You grow the soil that helps you grow the plants”. A cover crop is really anything that covers the soil and protects it from rain, trapping nutrients and preventing them from leaching downward, he explained. 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.

Cover crops are also called green manure when they are chopped up and turned into the soil in spring lettuces_after_cover_cropping.1024before 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.

From 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.

The Chadwick Garden, Martin explained, originally was heavy red clay. 35 years of soil building with bell beans and vetch cover crops and compost have established a level of fertility that now supports several acres of vegetables, fruit trees, berries and beneficial flowering plants. Fall-sown, spring ploughed-down cover crops are the sole fertilizer used for the better part of the last decade.

Soil_builder_cover_crop_mix.1600Martin explained that recent research now recommends planting a tandem 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 no where near as efficiently as bell beans.  Crimson clover seed is also 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.

A question came up about using inoculants on legume seed. Martin explained that 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.

We all followed Martin out to the cover crop trial plots to see how the different types were growing. Bark chips will soon be applied to the paths. All of the gardens are mulched several times per year with wood chips. A 10 year study, Martin explained, demonstrated the amazing benefits of ramial chipped wood which is the type the tree service companies provide for free.

We watched him work the soil lightly with a metal bow rake then broadcast 8-10 seeds per square foot. Weeds were already cleared but Martin said this step doesn’t have to be perfect. Afterward the area was raked again lightly 1-2″ down and covered with 3-4″ 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, he said.  Water in lightly.

There are 3 ways to fertilize, Martin said. You can buy chemical fertilizer which is expensive and doesn’t do much for the soil. You can apply compost, which being carbon based, ramps up beneficial fungal organisms in the soil. Or you can cover crop or grow green manure which increases beneficial soil bacteria. Orin Martin has proof of the benefits of the last two methods.



Beneficial Gardens in a Small Space


waterfall_2He told me that his was a one-of-a-kind garden, unique in such a small space and would I be interested in visiting some time? I love being invited to tour all types of gardens but I had an inkling that the garden of Rich Merrill, former Director of the Horticulture Dept. and Professor Emeritus at Cabrillo College, would be something special.

It was a beautiful morning when I arrived at Merrill's garden overflowing with flowering plants, small trees, edibles and water features. Many large boulders, surrounded by pebbles, caught my attention in such a small space. All part of the design to attract beneficial insects I was told. His organic garden is teeming with small beetles, spiders, predatory bugs, syrphid flies, parasitic wasps and lacewings. It's the ideal method of pest control, environmentally safe and free of cost.

While admiring his lovely garden, Merrill shared his knowledge of beneficials- from insects to birds to spiders to frogs and beetles. They are all part of the ecology of a successful habitat garden. I could barely keep up, writing down notes on my yellow legal pad as he weaved a story about how each of the elements in his garden contributes to its total health. I was never able to take one of his classes at Cabrillo College so this was a real treat. My own private class.

The wide diversity of plants in Merrill's garden provide moisture, shelter, prey and nutrition in the form of santivalia2nectar for carbohydrates and pollen for protein. His plants are "beneficial" plants because they foster beneficial insects. It just so happens  that many of these plants are also beautiful in the garden. Some of his favorites include composite flowers like sunflowers, marigolds buckwheat, scabiosa and santivalia or creeping zinnia.  They have flat  flower clusters with accessible landing platforms and small nectar and pollen to make it easier for insects to feed. They in turn eat the tiny eggs of the bad bugs in your garden. His is a complete ecosystem.

This 800 square foot garden happens to be in a mobile home park but any small space could be designed to be as beautiful and full of life as Merrill's. Most of my clients ask for a garden filled with color, hummingbirds, songbirds, butterflies and wildlife so I came away with lots of great ideas.

blue_thunbergia2Once a teacher, always a teacher. Merrill gave me a handout he'd prepared for Renee Shepherd of Renee's Garden, explaining in more detail why he lets the broccoli go to flower to attract beneficials and why he allows aphids on his cruciferous vegetables to feed the beneficial insects when prey is scarce so they are on hand should he have an outbreak of bad insects that might ruin his flowers and plants.

As we strolled within a border of palms, olive trees, phormium, bottlebrush, Marjorie Channon pittosporum and cordyline, Merrill showed me his philosophy of right plant in the right place in action. Asclepias curassavica, commonly called Mexican Butterfly Weed, has self sown on its own in unexpected spots. One happened to come up next to the gorgeous blue thunbergia by the pondless waterfall making an awesome combination. Both monarch butterflies and hummingbirds enjoy the nectar.

Next to a red salvia, a red and white bicolor Rose of Sharon made it's home. Merrill lets all his plants intertwine and the pink flowering Heckrottii honeysuckle was already inching up into an olive tree. Other salvias in his garden include Hot Lips, San Antonio and San Jacinto. There isn't room to grow any of the larger salvias, Merrill explained. He swears he doesn't know where the brilliant blue one came from. Must be from the "fairy dust" his wife, Dida says he sprinkled over the garden to make everything grow so lush.

She loves flowers for fragrance and cutting so in several beds they grow gardenia, lemons, roses and alstroemeria among the alyssum which is a prime syrphid fly attractor. Several bird of paradise, obtained from different locales in the hopes one will be hardier grow beneath a tall palm.

Merrill grows only the vegetables that do well and are the most nutritious like kale, onions, garlic, broccoli and collards. He enjoyed growing cucumbers this year and has a large pumpkin in the making for his grandson. The rest he gets from the farmer's market. He had developed his own strain of elephant garlic which is actually a leek and has a milder flavor than garlic. I left his garden with a gift of elephant garlic and lots of inspiration.



The Giants’ Garden


AT&T_Park 3A few Sundays ago I spent the afternoon at AT&T Park watching the Giants play baseball. It was kids day. Hundreds of Boy Scouts were attending the game in uniform. Kids were everywhere eating peanuts and wearing the orange and black team colors. Some were sitting with their grandparents, some very, very young fans in their parents arms being smeared with sun screen.  It was a beautiful day on the San Francisco Bay. Unfortunately, the team didn't get the memo that we were supposed to get another win against the Diamondbacks. Oh well, there's always next year.

A friend forwarded an article he saw in the SF Chronicle by Janny Hu recently about the Giants plan to create an organic garden behind the center field wall. The Giants Garden would be created between the left and right field bleachers in an area that is now concrete and an adjacent area where replacement sod is grown.

Plans for the edible garden include hydroponic troughs, concrete planters and living green walls which would supply produce for some of the parks' concessions, serve as an open air dining area and a community classroom during the offseason. If you're hankering for a nice kale and strawberry salad next season while you watch the game you're in luck. The Giants hope to have the garden ready for Opening Day 2014.

If the Giants can do it, you can, too. We all want the area around our homes to be beautiful, welcoming, productive, useful.  In designing landscapes for people I strive to integrate vegetables, herbs and fruit trees with flowering shrubs and perennials to feed the family while attracting hummingbirds and other wildlife. Not everybody has room for a separate vegetable garden and companion planting is a good way to avoid problems with pests and diseases.

Plants when attacked by pests, exude chemicals and hormones that actually attract nearby beneficial insects. Perennials like agastache, coneflower, coreopsis, scabiosa and yarrow are rich in nectar and pollen and  irresistible to beneficials. Many herbs also attract beneficials.  Cilantro in bloom is one of the top insectary plants.  Caraway, chervil, dill, fennel, lovage and parsley flowers also attract beneficials and are easy to grow among your other plants. Allow your salad and cabbage crops to bloom.  Arugula and brassica flowers are much appreciated by beneficials.

Plants like lettuces, spinach and swiss chard look great in the flower bed and flowers make great companions in the vegetable garden.
Dahlias repel nematodes. Geraniums repel cabbage worms, corn ear worms and leaf hoppers.  Plant them by grapes, roses, corn and cabbage. Marigolds discourage beetles, whiteflies and nematodes. They act as trap plants for spider mites and slugs. A word of caution,  don't plant them by cabbage or beans. Nasturtiums act as a barrier trap around tomatoes, radishes, cabbage and fruit trees. They deter whiteflies, and squash bugs and are a good trap crop for black aphids.

Herbs that help deter pests. Catnip/catmint repels mice, flea beetles, aphids, squash bugs, ants and weevils. Chamomile improves the flavor of cabbage, onions and cucumbers. It also accumulates calcium, sulphur and potassium, returning them later to the soil. As a host for hoverflies and good wasps it increases productions of essential oils in herbs. Summer savory repels bean leaf beetles and improves the flavor of beans. All beans enrich the soil by fixing nitrogen.  They are good for planting with all of your vegetables except onions, garlic and leeks.

Dwarf fruit trees can also find a place in the smaller garden. They can be grown in large pots or half barrels on the deck, too. Dwarf Garden Delicious apple is self-fertile and bears at a young age. Compact Stella cherry is also self fertile and is a good pollinizer for all sweet cherries.

If it's almonds you crave, plant a Dwarf Garden Prince almond. This compact 10-12 ft tree blooms mid-season with beautiful pale pink blossoms. Dense attractive foliage and good quality sweet almonds make this tree a nice addition to any garden. A patio-sized peach for smaller yards is the Dwarf Southern Flame.  Large, yellow, aromatic freestone peaches are firm, crisp and melt in your mouth. Tree height is just 5 ft and the fruit ripens early to mid July.

Planting flowers and edibles together makes sense and good use of your garden space.
 

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