Category Archives: vegetables

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.

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.
 

Tips for Vegetables, Pests and Plants with Bad Behaviors

Summer is officially almost here although we all know it actually starts on Memorial Day weekend. What fun stuff should we be doing in the garden? What problems should I be on the lookout for? What troublemakers should I avoid planting?

June is a busy time for plants. Some are just finishing up early spring flowering like rhododendrons, azaleas. camellias, lilac and wisteria. Prune off spent flowers and shape plants if needed. Other plants are just beginning to flower and would like a dose of organic fertilizer to really perform well.

Plant corn, lettuce and basil continuously to keep a steady supply. Speaking of basil, if yours died recently showing brown spots or streaks up the stem,  fusarium wilt, caused by a fungus, is the culprit. Carried by either the soil that affected basil plants have been grown in or by seed from an infected basil plant it's a common problem. There is no remedy for fusarium wilt. Destroy infected plants and do not plant basil or other mint plants in that area for 2-3 years.

Night time temperatures should be consistently above 50 degrees for basil. As long as you provide it with a hot, sunny location and plenty of water, it's among the easiest of herbs to grow in the garden or in a container. Steady, slow growth is the key to good taste, so amend the soil with compost and forgo the fertilizer. Basil contains the most oils when harvested before the flowers occur. The best way to delay flowering, as well as to encourage branching and new growth, is to harvest regularly by snipping of the end of the branches.

The best time to harvest is midmorning, right after the dew has dried, but before the afternoon sun bakes out the oils. At some point later in the summer, flowering will begin in earnest. Then it's time to harvest the entire crop, as flavor will go downhill soon afterward.

Insects are having a field day at this time of year, too. Put out wet rolled newspaper at night to collect earwigs in the morning. If you see notches on your rose leaves, it's the work of leaf cutter bees. These guys are beneficial and will go away shortly.

If your rose leaves look like lace then you have the dreaded rose slug. I have a friend who's rose shrubs were really hit by these. It's discouraging when you had visions of huge fragrant bouquets on every table. What to do?

The rose slug is actually the larvae of a wasp called a sawfly. Because they may have 6 generations per year they can do a lot of damage to your roses. Early detection is key. Start scouting for sawfly larvae in early May when they can be hand picked or washed from the leaves with a strong spray. If needed, spray the leaves with neem oil while the larvae are still small. Conventional insecticides are toxic to bees and kill the good bugs too.

During the winter they pupate in the soil and removing a couple of inches will help with controlling their numbers. Even cultivating the soil at any time will break up the cocoons.

Finally, think twice before planting rampant growers that are hard to control unless you use a deep edging that will keep them confined where you want. There's nothing wrong with a plant that spreads out in the right places, but let it overgrow that area and it quickly wears out its welcome.

Plants like chameleon plant ( Houttunyia cordata) , lamium, it's close relative lamiastrum and hypericum are  great plants in areas that are not close to your other planting beds. The deceptively delicate looking and impossible to ever get rid of Japanese anemone falls into this category also. To be forewarned is to be forearmed. Plan ahead.

Get out and enjoy your garden. The best way to nip problems in the bud is to walk around your garden with a beverage of some kind and just look.