There are now many, many varieties of greens that grow quickly, look appetizing and bring fast returns for the grower. Most of them are Asian in origin, although some of the newer ones have been developed in the U.S. They are mostly brassicas, and can be grown at whatever time of year you normally grow cabbage or kale. Here in central Virginia, we have a shorter brassica season in the spring, and a longer one in the fall. In spring, the brassicas will bolt when the weather gets hot, whereas in the fall, the weather is cooling, the days shortening, and the plants will not bolt. Having greens to eat in the fall does depend on getting them germinated and planted while the weather is still hot in June and July. See my article “Time to Start Those Fall Brassicas” in the June 2006 issue of Growing For Market, for general growing instructions. Some of the fastest growing Asian greens are ready for transplanting just two weeks after sowing (or you could of course direct sow them). These crops are a quick way to fill out your market booth or CSA bags. We find that people are very ready for some fresh greens as the summer thinks about cooling down. Asian greens are faster growing than lettuce and the seeds are better able to germinate in hot weather. They can be used as a catch crop in spaces where other crops have failed or otherwise “finished early”. If you keep a flat of seedlings ready, you can pop plugs into empty spaces as they randomly occur.
Flavors vary from mild to peppery, so if you or your customers don’t want hot mustards, read the variety descriptions in the catalogs before growing a large area. We found ourselves left holding large bags of Red Giant and Southern Wave mustard seed after an impulse buy. Happily, we were able to use it up for baby salad mix this spring! Colors cover the spectrum through chartreuse, bright green, dark green and purple.
These greens are nutritious as well as tasty. They are high in carotenoids, vitamins A and C, calcium, iron, magnesium and fiber. They also contain sulphoraphanes (anti-oxidants), which fight against cancer and also protect eyes from the UV damage which can lead to macular degeneration. If you need more persuading, these vegetables help prevent high blood pressure, heart disease and stroke.
Asian greens fall into two main groups: The turnip family, Brassica rapa, of Asian origin; and the cabbage family, B. oleracea, of European origin. Some crops are Brassica rapa, var pekinensis (napa cabbage and michihili). Others are B. rapa, var chinensis (bok choy), while others are B. rapa, var japonica (mizuna).
Our favorite Asian greens include Napa cabbage. We like ‘Blues’ best – 52 days from seed to harvest – though ‘Kasumi’ has the best bolt tolerance, and is larger (5 pounds rather than Blues’ 4 pounds). ‘Orange Queen’ is a colorful, though slower growing variety (80 days), hardy to about 25°F.
Pak Choy/Bok Choi (we grow Prize Choy or Joy Choi). Previously known as Chinese mustard cabbage, it has sturdy white leaf stems and big green leaves, and is usually harvested as a head, 12-15” tall, but can be harvested as individual leaves for a mixed braising greens or stir-fry combination. 45-55 days to maturity.
Mizuna/Kyona, now available in purple, has ferny leaves that are very pretty in salad mixes. It has a mild flavor, and regrows vigorously after cutting. Thin to 8-12” apart. Adds loft to salad mix. Only 40 days to maturity, and very easy to grow, cold and wet-soil tolerant, and also fairly heat tolerant, (well, warm-tolerant). It can be used for baby salads after only 21 days. Mibuna is similar to mizuna, but less ferny and more spoon shaped.
Tatsoi/Tah Tsoi is a small plant, a flat rosette of shiny, dark green spoon-shaped leaves and white stems. It matures in 45 days. We usually direct sow this and then thin into salad mixes, leaving some to mature at 10” across for cooking greens. We also transplant at 6” if that suits our space use better. It has a mild flavor, attractive appearance and is easy to grow Tatsoi is extremely cold tolerant, hardy to 22°F. 45 days to cooking size. 21 days for baby salads.
Yukina Savoy is like a bigger tatsoi, with blistered dark green leaves and greener stems, about 12” tall. Delicious flavor. We transplant this at 12”. It is both heat and cold tolerant. 45 days to full size, 21 days baby size.
Komatsuna is also known as Mustard Spinach and Summer Fest. It is now available green and red, and grows into a large cold-tolerant plant 18” tall. Individual leaves can be picked and bunched, or the whole plant can be harvested. The flavor is much milder than the English name suggests, being mildly peppery. 35 days to full size, 21 days to baby salad size.
Tokyo Bekana is a very fast growing tender chartreuse (yellow-green) leafy plant, which we have often used for salad leaves to get us through any late summer lettuce shortages. It has a mild flavor and even so, I have been surprised that many people don’t even notice they are not eating lettuce – I suppose enough salad dressing masks all flavors! 45 days to full maturity, 21 days to a baby crop.
Maruba Santoh is also a fast-growing chartreuse tender-leafed plant, similar to tokyo bekana but less frilly. The wide white stems of the mature plant provide crunch for salads, along with the delicate leaves; or the baby leaves can be harvested. Fairly bolt tolerant. Only 35 days to maturity.
Senposai is the star of Asian greens as far as I’m concerned. It is quite heat tolerant and cold-tolerant, a big plant producing large, round, mid-green leaves which are usually harvested with the cut-and-come-again method. It can be very productive, and is fast-growing. Transplant at 12-18” spacing, it really will use all this space. It cooks quickly (much quicker than collards), and has a delicious sweet cabbagey flavor and tender texture. I understand it is a cross between komatsuna and regular cabbage. Only 40 days to maturity.
These crops have the same requirements as other brassicas, with the addition of extra attention to providing enough water during hot weather to prevent bitter flavors and over-heating of the mustardiness, and closer monitoring of pests, which may have built up large populations during the summer. Very fertile soils grow the best Asian greens, so turn in leguminous cover crops or compost to provide adequate nutrition. A variety of well-drained soils can grow good brassicas. Nitrogen and phosphorus requirements are usually met by the initial (pre-planting) soil fertilization. Potassium requirements are high, so if your soil is low in potash, add woodash, granite dust, composted animal manures or kelp meal. Calcium, boron, manganese, molybdenum and iron are also important for good development of brassica crops. Most biologically active soils can supply enough, but if you are bringing new soils into vegetable production, add compost.
We use row covers on our brassicas until they are large enough to withstand the Harlequin bugs.
We almost always transplant our brassicas because we use our growing spaces very intensively, and transplanting gives the previous crop some extra weeks to finish up. If we have 4 weeks between the end of one crop and the brassica transplants going in, we sow a buckwheat cover crop to add organic matter and smother weeds. We’d rather make use of this cover crop opportunity than direct sow greens, usually. We grow a lot of brassicas and our crop rotation is always pushed and stretched by the amount of brassicas we’d like to plant.
We make an outdoor nursery bed, with rows about 9-10” apart, and sow at about 3 or 4 seeds per inch, and cover with rowcover. The seedlings will emerge in as little as 3 days in summer temperatures.
You could also sow in plug flats (such as 608s) in a greenhouse, if that suits you better. I prefer outdoor seedbeds, because it is easier to keep the plants watered, and because after the end of May, I want to be done with the greenhouse’s demands for water 4 times a day.
The third option, direct sowing, does have the advantage that the thinnings can be used for salads.
We start sowing our fall Asian greens for outdoor planting around 6/26 and repeat a week later for insurance (7/3), the same dates we sow fall broccoli and cabbage. One week after sowing, we check the seedlings, thin to 1”, weed, water, and decide if the germination rate is high enough (80%), or if we need to sow more. The last date for sowing these crops is about 3 months before the First Fall Frost date. In our case that means July 14-20.
Some of the faster growing Asian greens are ready to transplant two weeks after sowing. Napa cabbage, Tokyo Bekana and Maruba Santoh are in this category. Most others transplant best at 3-4 weeks of age (less time than needed in spring). Adding this up, you’ll see we are transplanting them outdoors from 7/10 to 7/31.
It’s important to minimize transplant shock, so water the plants well an hour before you dig them up, get them in the ground again as quickly as possible and water again. Transplanting after the hottest part of the day will help enormously. If transplanting is your idea of a pleasant evening, do it then. Otherwise plan to spend an hour or so transplanting a the end of each afternoon until you are done. Shade cloth or rowcover will help keep the breezes (if any!) and the brightness off the plants. Putting the fabric over hoops of some kind will help keep the atmosphere more “buoyant” and reduce the chance of over-heating.
These crops are relatively shallow-rooted, and need good amounts of water to grow pleasant-tasting leaves. Drip irrigation saves water and reduces disease and weed pressure. On the other hand, overhead irrigation can be cheaper and easier to set up for crops which will be harvested before much time has passed. And overhead sprinklers can wash off aphids, and could be all the control measures you need for that pest. One inch of water per week is enough, except during very hot weather, when two inches will work better.
Our biggest pests are Harlequin bugs. We usually try to pick and kill as many as possible in the spring, and again when we plant out fall brassicas, in hopes of keeping the population under control.
Some years we have flea beetles, which we have “done in” with Spinosad, an enzyme produced by a natural organism. Hb nematodes will control them, or Neem, or the braconid wasp Microtonus vittage Muesebeck. Garlic spray, Millers Hot Sauce, kaolin and white sticky traps have also been suggested. Or catch them with a vacuum cleaner, or inside a bucket coated with Tanglefoot (hold the inverted bucket over the plant, shake it, and catch the jumping beetles in the goo.) Useful (reassuring?) information is that brassica flea beetles are a different species from the ones that plague eggplant, and they can only fly a few hundred yards).
Aphids generally are more of a problem in the cooler weather of early spring, before their predators have arrived in high enough numbers. If they get out of hand, insecticidal soaps can be used.
Caterpillars: rowcover will keep them off, Bt will kill them if rowcovers fail. Bt degrades rapidly in sunlight so is best applied early evening or early morning, whichever seems likely to catch most caterpillars. The beneficial fungus Beauvaria bassiana infects caterpillars, but can get costly. Caterpillars have many natural enemies. In our garden the paper wasps eat caterpillars, and we also have the parasite Cotesia glomerata. Plant small-headed flowers such as alyssum to attract beneficial insects.
Slugs – Coming from the moist and verdant islands of Britain, I used to think slugs were an endangered species in Virginia, as I rarely saw any. When we put up our hoophouse, though, I found we were farming them! Slugs can best be caught at night with a flashlight. (Well actually with scissors, by flashlight!)
Grasshoppers can be a problem – we are trying to determine when the young hatch in July, so we know when we need to be most alert and attentive to keeping them off our plants. In our hoophouse we have been troubled in January by the Vegetable Weevil larva, which comes out of the soil at night, and makes holes in the leaves. We have used Spinosad against them, with some success.
A net fabric with small holes would be better than rowcover in hot weather, as the airflow would be better, and the heating less, Some people use nylon bridal netting from a fabric store. ProtekNet Pest Control Netting from Dubois (who sell the biodegradable, compostable BioTelo Mulch Film), is a new product, made of clear high density polyethylene, with U.V. resistance and a lifespan of 8 to 10 years. It has a mesh size of 6x6, and its light transmission is 90%. It also protects crops against weather damage. Proteknet can be tailor-made to specific dimensions and also in various other weights and mesh sizes. I haven’t seen it yet, so I don’t know what size the 6x6 mesh is, but from the photos, it’s 1/6 the length of a cucumber beetle. See their website www.duboisag.com/catalog.php?lang=en&product_id=523. Enviromesh from Agralan is another promising sounding product to keep insect pests from crops.
Pam Dawling is the garden manager at Twin Oaks Community in Virginia. Contact her at [email protected].