We’ve all heard of cash crops, those garden plants grown as food, or to sell. But, what can you do with a growing area after a crop is harvested? Catch crops!
Whether you grow your edibles in the ground, raised beds, or containers, there comes a time when the crop matures and the plants are harvested. What’s left? Usually, bare soil and a bunch of stems, cut off at ground level. It’s not attractive, it’s not good for your soil, and it’s bad for the environment.
After a crop has completed its life cycle, the soil is probably a little depleted. The last thing it needs is exposure to eroding wind, sun, and rain. But that’s exactly what it gets. Without the supporting roots and shading leaves, topsoil is exposed to the elements, which can cause it to simply blow or wash away. You’ve worked too hard and too long in the garden to lose all that valuable topsoil, so how can you protect it?
Plant a catch crop
Catch crops are a combination of cover crops and succession planting. Rather than leaving the soil exposed and the beneficial soil microorganisms to starve, cover crops are used to maintain the relationships between plants, soil, and mycorrhizae that produce nearly all the plants we eat. Catch crops are fast-growing plants that fill in the spaces left behind a harvested crop. In commercial agriculture, catch crops are planted after a field is harvested. In the home garden, you can plant your catch crop before the current crop is even done, providing your soil (and your view) with year round protection.
Which plants make good catch crops?
The best catch crops grow very quickly. Radishes, rye, arugula, mustard, lettuce, endive, sunflowers, buckwheat, beans, barley, and oats are generally the best choices for catch crops. Research has shown that these crops help retain nitrogen in the soil, improve soil structure, and prevent erosion when grown as catch crops. Other crops, such as sorghum hybrids, do not make good catch crops. One sorghum-sudangrass hybrid (Sudex) resulted in 50 to 75% mortality of tomato, broccoli, and lettuce crops. This type of chemical warfare is called allelopathy. Stick with the plants listed above. Your soil will be better off, plus you can harvest the beans, sunflower seeds, salad makings, and grain, assuming you do not use your catch crop as a green manure. [If the catch crop is cut and allowed to decompose in place, it becomes a green manure, feeding the soil and improving soil structure even more.]
Benefits of planting a catch crop
In addition to preventing erosion and keeping your garden attractive, catch crops prevent important minerals [plant food] from being washed away. This reduces ground water contamination. It also improves the size and quality of the crop that follows! Research has shown that crop yields increase by nearly 5%, simply by being grown after a cover crop. Using catch crops and cover crops also increases biodiversity. We are not simply talking about plants and animals here, either. Biodiversity is also occurring at the microscopic level. Soils that contain a wider range of microorganisms and other living things is healthier. Healthier soil grows better food for you and your family. Catch crops also help block sunlight to weeds, competing with them for water and sunlight. This makes it less likely that local weeds will survive long enough to produce seeds that grow into future competition. This reduces the need for herbicides (or the number of hours spent weeding each year).
As your cash crops near the end of their normal lifecycle, be sure to plant catch crops!
Horses and cows love it, but what is alfalfa? Is it the same thing as hay? What about straw? Let’s find out!
To start, hay refers to any member of the grass or legume families that have been mown and dried as fodder, or animal feed. You can find oat hay, wheat hay, ryegrass hay, clover hay, timothy hay, alfalfa hay, and others. Straw, or stover, refers to the dried stalks leftover after harvesting grains, such as oats and rye. Straw is generally used as bedding, though it can be used as a low quality feed. Alfalfa stover makes a good bedding for rabbits, guinea pigs, and hens.
Alfalfa is a legume, like peas and beans, but it grows more like oats or barley. Native to southwestern Asia, alfalfa is primarily grown as fodder for livestock. It is either dried and baled, or fermented as silage. Many gardeners are finding that alfalfa’s deep roots and nitrogen-fixing ability make it an excellent cover crop or green manure.
Alfalfa (Medicago sativa) is a flowering perennial in the pea family. Alfalfa was first farmed, over 6,000 years ago, in Iran. Then the Persians took this valuable crop to Greece around 500 BC. The Latin name, Medicago, refers to the ancient people of Iran, the Medes. The Arabic word for this crop, al-fiṣfiṣa, is what gives us our common American name for it. The rest of the world has been calling it lucerne, but that is slowly changing as more of the world’s alfalfa crop is grown in California.
The alfalfa plant
As a perennial, alfalfa plants grow for an average of 4 to 8 years, though they can live for 20 years. These deep-rooted plants, while only 3 feet tall, can reach down as much as 49 feet to find water! I guess it’s safe to assume that they are drought tolerant. In fact, alfalfa is rated as drought-resistant, meaning it can go for long periods of time without any water at all. Most of the time, alfalfa roots only go 6 to 9 feet deep, which is still pretty impressive, when most annual vegetables only root 6 to 12 inches down. Once established, alfalfa plants create a sturdy crown at ground level. Much like sorghum, these crowns contain bud shoots that make it possible to harvest a crop only to have a new one grow. Alfalfa is usually mown 3 or 4 times a year, but it can done up to 12 times a year, in an ideal microclimate. Overgrazing, or over-harvesting, can damage the crown. After flowering, pollinated flowers produce spiraled fruits that contain 10 to 20 seeds. Alfalfa plants uses chemicals to prevent other alfalfa plants from growing nearby. This is called autotoxicity. It is triggered after the first seeding of an alfalfa plant and it continues for the remainder of that plant’s life. because of this, crop rotation with corn, wheat, or other crops must be used before replanting an area with more alfalfa.
Nutrients in alfalfa
Alfalfa is a highly nutritious plant. It contains high levels of protein, fiber, and carotenoids. Alfalfa is highly combustible and it can cause bloating when eaten fresh, by livestock, so it is normally dried first. Alfalfa, like other legumes, also has root nodules that contain beneficial bacteria, Sinorhizobium meliloti, that are able to convert atmospheric nitrogen into a form usable by plants. You can buy alfalfa meal, as a nitrogen source, or you can grow your own.
How to grow alfalfa
Alfalfa, like wheat, can be sown in either spring or autumn. These plants need a neutral soil pH of 6.8 to 7.5 to thrive. Other factors are less important. Alfalfa uses a lot of phosphorus and potassium, but our Bay Area soil tends to have both in abundance. (See Soil Test) Alfalfa seeds are planted 1/2 inch deep and should be spaced at 6-inch intervals. When farmers plant alfalfa, they use a machine, called a drill, that inserts a single seed at the right depth and spacing, as the farmer drives over a field. Since alfalfa is sensitive to weed competition in its early development, the proper spacing is rather important. If you are growing your own alfalfa for the first time, use 1/4 pound of seed over a 25 square foot area (or 20 pounds of seed per acre). Planting it will take some time, because these seeds are really tiny, so put on some music and wear a hat. Alfalfa does not grow well on slopes or in areas with shallow soil. [Raw, unsprouted alfalfa seeds contain chemicals that can be toxic to humans, causing lupus-like symptoms, so don’t eat them. Also, there is no scientific research to verify medical claims made about alfalfa or its sprouts. Leave alfalfa to your soil and the livestock, where it belongs.]
Alfalfa pests and diseases
Blister beetles, thrips, spider mites, weevils, armyworms, nematodes, cutworms, grasshoppers and crickets, leafhoppers, and aphids are all attracted to alfalfa. Alfalfa is prone to several root rots, such as rhizoctonia, phytophthora, and Texas root rot. Other alfalfa diseases include fusarium wilt, downy mildews, anthracnose, bacterial wilt, and verticillium wilt. Since alfalfa, along with clover, rye, and other legumes can host bean mosaic, it is a good idea to keep some distance between them and your bean crops. Also, voles, pocket gophers, and ground squirrels can be major alfalfa pests.
Alfalfa as insectary and habitat
Insectaries are plants that attract and provide for insects. Alfalfa’s purple flowers are a big favorite of honey bees and other pollinators. Commercially, alfalfa and cotton are intercropped because of predatory insects attracted to alfalfa help to protect the cotton crop. Alfalfa also provides food and habitat to over 130 bird species and many other forms of wildlife. Alfalfa flowers are responsible for the majority of the honey produced in the United States. That being said, it ends up that bees and alfalfa don’t necessarily play well together. The structure of an alfalfa flower makes it so that a western honey bee gets knocked in the head each time they land on a flower. Apparently, bees don’t like getting knocked in the head, so they sip alfalfa nectar from the side of the flower, foregoing the pollen transfer. Since it takes young bees a few knocks to the noggin to learn this trick, pollination still occurs, but only because beekeepers make sure there are plenty of inexperienced bees in the hive when they service alfalfa fields. Alfalfa leaf cutter bees do a much better job of pollinating alfalfa than honey bees.
Even if you only have a driveway or fence strip, try your hand at planting some alfalfa. It will improve the soil, attract pollinators, and it needs no care at all, once it is established!
Lettuce may not look like it has much to offer, but this member of the sunflower family can provide good food, ground cover, and fun!
Lettuce is a biennial garden staple that finds its way into most burgers and lays the foundation for nearly every salad ever made. With half of the world’s lettuce crop being grown by China, and numerous cases of E. coli and Salmonella poisoning in bagged salads, lettuce should be one of the first garden plants you try. Fresh lettuce is cheaper, tastier, safer, and far better for the environment than anything that has been shipped from halfway around the planet.
History of lettuce
The ancient Egyptians took advantage of a certain type of weed, whose seeds contained a lot of oil. Over time, those weeds became domesticated and the edible leaves started being used for food and medicine. The Romans gave lettuce its Latin name, Lactuca sativa, for the white latex (lactuca) that drips from cut stems. (Sativa means cultivated.) Being people, we saved seeds from our favorite types to ultimately create nearly 150 varieties of lettuce.
Lettuce generally grows in a crisphead, loose leaf, or romaine form, but there are seven cultivar groups:
Loose leaf and romaine lettuces can be harvested in a cut and grow method, in which outer leaves are removed for consumption and the plant is allowed to continue providing edible leaves for the entire growing period.
How to grow lettuce
Lettuce, like spinach, tends to bolt when it gets really hot outside, so fall, winter, and spring are the best times of year for growing lettuce in the Bay Area. Lettuce can be grown in containers, straw bales, in the ground, or on a window sill. Lettuce prefers sun, but it can grow just fine in shade gardens, too! In spite of its taproot, lettuce does not need a particularly large or deep container to provide you with fresh leaves for your sandwich or salad.
Lettuce seeds are really tiny, so don’t try planting outside on a windy day. (Yep, I learned that one the Hard Way.) Seeds only need to be covered with 1/4” of soil, but they must be kept moist until they germinate. Spacing between plants depends entirely on the variety. Keep planting new seeds every few weeks, in succession, for a continuous harvest.
Once temperatures start rising, your lettuce plants will probably bolt, or go to seed. You can tell this is happening because your docile, rounded lettuce plants will suddenly send up a spike of growth from the center that looks very un-lettuce-like. If you allow this to continue, and I urge you to do so, your lettuce plant will become too bitter to eat, but it will produce flowers and seeds for future generations. I allow my lettuce plants to go to seed and let them fall where they will. (You can also wrap bags around flowering heads to collect seeds.) I now have an attractive foodscape, with all sorts of lettuces growing in all sorts of places. Unless it’s the peak of summer, I can create a fresh salad with a variety of lettuces simply by walking around my backyard!
Lettuce pests & diseases
Aphids are a lettuce plant’s worst enemy, with snails and slugs being a close second. Earwigs, cutworms, weevils, rabbits, and voles will all be attracted to your lettuce plants, and white mold can sometimes be a problem.
Does lettuce really turn brown faster when cut with a knife? No, it doesn’t.
Finally, any packet of lettuce seeds that you buy will have far more seeds than you will be able to use in a growing season. Solution: invite your friends over for a seed-luck. What's a seed-luck? That's when everyone brings a packet of a different type of lettuce (or other) seed, a dessert, and a bottle of wine. You will need to provide little packets or envelopes for guests to (decorate and) use to take their bounty home. A good time is sure to be had by all, and everyone ends up with a bigger variety of plants!
Beans, beans, the magical fruit.
The more you eat, the more you…well, you know.
What you may not know about this nutritional powerhouse is that it is crazy easy to grow, germinates at lightening speed, adds nitrogen to the soil, and is just plain fun to watch grow.
Beans are the edible seeds of the legume family. Often, but not always, these seeds are kidney-shaped. There are over 40,000 different type of beans found in the world. Some of the more common varieties are:
How's that for a family tree?
How to grow beans
Growing most beans is really simple. Seeds can be planted 1/2 to 4 inches below soil level, watered a little at first, and then only occasionally afterward. Under ideal conditions, some beans can germinate within just 4 days, making them an excellent crop for children. Beans are not very competitive plants, so you can help your bean plants thrive by regularly weeding the area until they are firmly established. Because beans grow so fast, they can be a fun window sill garden addition.
If you have heavy clay soil, be sure you do not overwater. Clay soil can hold so much water that plants will rot or drown. Now, if you want to get really fancy, you can inoculate the seeds with a species-specific Rhizobium bacteria. This does not mean giving tiny shots to each and every seed (But it’s a funny image, right?) Beans can be dusted with, rolled in, or briefly soaked in the inoculant at planting time to help them get the most nitrogen out of the soil, for a better start. Personally, I’ve never used inoculants, but many gardeners and most farmers swear by them, especially in areas where beans have not been grown for a long time.
Bean growth habits
Generally, bean plants come in one of two growth habits: bush (determinate) or vine/pole (indeterminate). As with other crops, determinate types tend to flower and develop pods within a set time frame, whereas indeterminate types tend to continue on for longer periods of time, producing pods as they grow. Beans prefer plenty of sunlight, but they can be grown in partial shade, as well.
Nitrogen boosting beans
Many orchardists plant beans and other legumes among fruit trees as cover crops to improve soil structure and add nitrogen to the soil. You can do the same thing by intercropping beans with other garden crops. Adding beans to your garden or landscape can help fix atmospheric nitrogen into the soil, making it available to other plants (assuming you cut your beans down and let them decompose before they go to seed. Cowpea roots are pretty tough and deep, so they can also help improve soil structure and reduce compaction. Beans are also part of the Three Sisters method of growing used by Native Americans. The Three Sisters Method intercrops corn, squash, and beans to make the most of available growing space, soil nutrients, and water resources. The corn grows tall, the beans climb the corn, and the squash shades the ground and reduces weed competition with wide leaves.
Beans and crop rotation
If you grow beans regularly, it is a good idea to rotate the bean crop with sunflowers, tomatoes, or wheat, to interrupt the life cycle of some fungal pests, such as bean rust. Bean seedlings are susceptible to damping-off disease. UC Davis provides this extensive list of bean diseases:
Aphids, armyworms, cucumber beetles, cutworms, darkling beetles, leafhoppers, leaf miners, loopers, lygus bugs, spider mites, stink bugs, thrips, weevils, whiteflies, and wireworms are all attracted to bean plants. The corn maggot larvae (Delia platura) and some caterpillars may also gnaw on your planted beans, as well. It’s amazing we get any beans at all, with a list like that! The truth is, bean plants are very productive and these potential problems are all relatively manageable.
Bean seed sources
As tempting as it may be to plant beans that were bought at your local grocery store, this is a bad idea. Those beans can carry diseases that you may never be able to get out of your soil, once they arrive. These diseases are not harmful when eaten by people, but they can be devastating to baby bean plants. Instead, invest in certified bean seed, and then save seed from your harvest for next year’s planting!
As a food, beans are high in protein, fiber, iron, potassium, thiamine, vitamin B6, and folic acid, with no cholesterol. Wikipedia has an excellent graphic that shows the protein, finer, and iron content of various beans. [Spoiler alert - lentils and kidney beans top the chart!]
And if you want to avoid the undesirable side effects of eating beans, be sure to change the water a few times during soaking and/or cooking.
Finally, according to the Smithsonian, kidney bean leaves can be used to trap bedbugs!
Now you know.
Black-eyed peas are said to bring good luck when eaten on New Years’ Day, but don’t wait that long! Put them to work in the garden for better growing all year.
Green manures are crops that are cut and either dug back into the soil or allowed to decompose on top of the soil, before they go to seed. Cowpeas will keep adding nitrogen to the soil right up until they start producing baby cowpeas of their own. Then, that nitrogen is absorbed by the plant and put to use. The nice thing about edible cover crops is that, even if you miss the mark and the plant goes to seed, you still get food!
Cover crops are grown for several reasons. They prevent erosion, add organic matter and nitrogen to the soil, reduce weeds and deter some soil borne pests.
Cowpeas are drought tolerant, germinate rapidly, and don’t seem to be bothered by heavy clay soil. In fact, these garden workhorses can be used to break up compacted soil with little to no effort on your part! While these beans prefer sun, they can also be incorporated into shade gardens. Fusarium wilt, aphids, weevils, and pod borers are the most common pests.
Beans have long been used in companion planting or intercropping. Native Americans used the Three Sisters method of growing beans, squash and corn together. The squash shaded the ground, the beans climbed the corn and the corn soared skyward with the shaded ground and nitrogen-rich soil.
How to grow cowpeas
If you have areas of compacted or bare soil, it is simple enough to poke holes in the soil and drop in a cowpea. Cowpeas are not particular. The hole can be 1-4 inches deep. Plants should be spaced 2 to 3 inches apart and protected from birds until they sprout, which can happen in as little as 4 days!
If you are feeling particularly creative or ambitious, you can plant cowpeas into patterns around trees, walkways, or other landscape features. As the plants come up, they will add a new texture to the garden, along with improving the soil structure and nutrient content!
Condiment or cover crop, mustard’s sunny yellow flowers, tasty seeds, and deep tap roots make it a useful plant worth learning about.
A member of the Brassica family, mustard is a popular hot dog condiment and a cheery yellow weed that grows in even the driest areas. Before ripping out any stray mustard plants in your garden, consider these benefits:
As mustard nears the end of its life cycle, you can feed the soil or feed yourself. By mowing the plants before they go to seed, nutrients are added to the soil. If the plants are allowed to go to seed, the seeds can be collected and used in cooking or to make your own prepared mustard. The condiment is made by combining crushed seeds with vinegar and water. The leaves (greens) are also edible and oil can be extracted from the seeds.
Mustard is related to radishes and turnips. People have been growing it for nearly 4,000 years. There are three basic types of mustard: white (Sinapis hurta), black (Brassica nigra), and oriental (Brassica juncea). White mustard is most commonly used as a cover crop.
Ground cover refers to low-growing, spreading plants that help prevent erosion, weeds, and water loss.
Bare dirt in the garden is not a good thing. Naked soil is vulnerable to wind and water erosion, compaction, and nutrient leaching. The Dust Bowl of the 1930’s is a perfect example of what happens when soil is not managed properly. Topsoil is a precious commodity and we all need to work to protect it. Ground cover is an excellent method that requires very little effort and improves biodiversity in the garden.
Benefits of planting ground cover
As the roots of ground cover plants work their way deeper into the soil, they help prevent erosion and the loss of nutrient rich topsoil and water. The leaves and stems shade the ground, stabilizing temperatures. Ground cover plants also reduce the chance that weeds will grow. In fact, ground cover plants are used to replace weeds.
Ground cover plant selection
Ground covers are traditionally shorter plants, but they come in a variety of heights, colors, and textures. There are five basic types of ground cover:
A good resource for plants suited to the Bay Area can be seen at the UCANR pages on ground cover. Wikipedia also provides links to many popular ground cover plants. Keep in mind, when selecting ground cover, that many of these plants will spread and fill an area. Invasive plants, such as Algerian or English ivy, ice plant, periwinkle (Vinca major) and licorice plant should not be used. In theory, traditional sod lawns are a form of ground cover, but they are unsuitable for drought-prone areas, requiring unsustainable amounts of water and nutrients.
Yarrow (pictured) makes an excellent ground cover. It can grow as tall as 2’, but will maintain a low growth if it is mowed occasionally while still young. It grows well in our hard clay soil and its soft feathery texture feels wonderful on your feet! Oregano and other low-growing herbs smell wonderful as you walk on them, and curly endive is surprisingly durable. If you don’t mind some height, annual rye grass has been shown to put roots down as far as 40”, helping to break up compacted soil. Mustard can help, too.
Ground cover vs. cover crop
Cover crops are usually grown with the intention of pulling them out of the ground and leaving them on top to decompose, or digging them into the soil, to return all of the nutrients contained in the plants back to the soil. Ground covers are plants grown with the intention of leaving them to continue growing indefinitely.
Plant-less ground covers?
Rather than exposing valuable topsoil to the elements, mulch is another option to ground cover plantings. Wood chips can be found for free from local tree trimming companies and it makes an excellent protective barrier. As the mulch breaks down, nutrients are added to the soil. Also, the mulch helps retain moisture and stabilize temperatures, providing a safe haven for earthworms and microorganisms that improve soil health.
If we say something is sustainable, we mean that it can keep going. Since agriculture and gardening are critical to our food supply, being sustainable is pretty darned important.
Until the 1980’s, food production was focused on the industrial production of single species (mono crops), using chemical fertilizers and pesticides, until the soil was exhausted. You can only do that for so long, before you run our of places to grow food. In 2002, at the International Society of Horticultural Science’s First International Symposium on Sustainability, it was agreed that sustainable agriculture and gardening were critical for the “well being of human societies”.
Sustainable gardening incorporates practices that reduce water, energy, time and chemical consumption, while producing food year-round and protecting the environment. These practices take the following issues into account:
Design for sustainability
Whether you already have a garden or are just starting out, you can design a garden or landscape for sustainability. Native plants are always your best bet because they put millions of years of evolution to work for you, conserving water, reducing the need for chemicals, and freeing up your time. Lawns are notorious water wasters and, quite honestly, most of us are not British aristocracy. Other plants, such as oregano, yarrow, or clover, make excellent, low-growing ground covers that use less water and rarely, if ever, need mowing.
These tips can help you create your own sustainable garden:
Late autumn and early winter often leave our gardens looking bare and unsightly. One way to improve both the appearance and the health of your garden is to use winter cover crops.
Cover crops, also known as green manure, are grasses and legumes that grow quickly. As soon as summer crops are harvested and the last, struggling tomato plant has succumbed to frost, you can plant your cover crops. Any rains that come will help speed their growth. Before they can flower, they are cut back and/or tilled back into the soil.
Legumes are particularly valuable as they add nitrogen to the soil. Popular legume cover crops include Black-eyed peas (pictured above), Fava beans, soy beans, red or crimson clover, and hairy vetch. You can even grow peas and keep trimming the tips (which are excellent in salads) to prevent them from flowering and going to seed. Once a legume has gone to seed, it begins pulling nitrogen from the soil like any other plant. Of course, there's nothing wrong with fresh peas and beans!
Cover crops also help reduce erosion, suppress weeds, and improve soil health. Inexpensive and easy to grow, cover crops are a simple investment in your garden’s long term health. [They look nice, too!]
You can grow a surprising amount of food in your own yard. Ask me how!
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