Mary’s best (and easiest) veggie garden primer.

How Does Your Garden Grow?

by Mary Jasch, editor DIG IT! Magazine

Now that it's Spring, every gardener's wish to get outside and plant has finally come true. With sky high vegetable prices and a greater awareness of healthy eating, everyone can grow their own veggies in garden plots, raised beds, deck planters or any small space. Here, experts from Rutgers Cooperative Extension (RCE) New Jersey Agricultural Experiment Station (NJAES) offer great tips on how to grow your best garden.

garden flowers
Shawna Bengivenni grows flowers to protect her organically grown garden in Wantage.

First, get your soil tested every few years to learn fertility levels, then supplement as needed. If levels are adequate, basic fertilizer requirements of NPK (Nitrogen, Phosphorous and Potassium) are about equal with a little extra side-dressing when the plants start to mature. Use composted manure or commercial fertilizer. Next, sow seeds directly or buy transplants from local garden centers or farm markets. "People go to big box stores and grab whatever they have and stick them in the ground, maybe in time, but likely the varieties that are grown aren't going to do very well in this region," says cool season vegetable expert Rick VanVranken, agricultural agent, RCE Atlantic County. "The big box stores contract with one or two growers around the country and sell the same varieties to all the stores. They don't take into account regional differences. Small garden centers and farm markets will have varieties that do better here because they're growing some for themselves as well." Plant cool weather vegetables now and warm weather veggies around May 20 and dig in fertilizer as you plant. Get started!

Cool season, through mid-April

Set cauliflower and broccoli plants out now. If you don't plant large enough plants, or the right varieties, they will either not form a head (flower buds) or they'll bolt and go to flower. Other stress factors that cause pre-mature, subpar heading are low nitrogen and micro-nutrients, inadequate watering, disease and insects. If a tag on a variety reads "tolerates warm weather", use it for a later planting.

Leaf lettuce grows faster and easier than heading types. Plant transplants now for a quick harvest.

Cabbage grows from the inside out, and the head forms as older, outer leaves cup together. So if you dust cabbage with insecticide or cornmeal (it works!), you don't have to worry about it getting inside the head. You can protect the cabbage as it grows covering the plants with "floating row covers", a.k.a. insect barriers. The material prevents insects like moths, flea hoppers, cabbage loopers and maggots (from a fly) from landing on the plants, but lets in sun and rain. As you plant seedlings, the fly is there waiting to lay eggs at the base of transplants. Cover cabbage family plants immediately when setting them out and leave the barriers on until harvest.

Be careful when you choose your spinach. Two tropicals, New Zealand Spinach and Malibar Spinach, are not the real thing, they just taste like it, and grow only in the heat of the summer. True spinach is a cool season crop. If it turns bright yellow, add lime to boost magnesium content and make Popeye strong.

Beet "seeds" are actually a fruit containing multiple seeds that produce several seedlings. Thin them to 2-3 inches so beet roots form, and eat the baby greens. Beets, spinach, chard, and cabbage family plants are all sensitive to boron levels in the soil. A deficiency produces black spotting on beet leaves and roots, and hollow stems and heads on cauliflower and broccoli that turn black or brown on the inside.

Want to grow nice long carrots like the supermarket sells? Forget it, or build a raised bed. Plant short varieties instead but add sand, peat-like mix and lots of compost. Carrots need deep, well-drained fertile soil and a floating row cover to dissuade attacking insects.

You may think corn is a warm season crop, but not entirely so. Plant an early season variety by mid-April to beat the worms that get into ears. Populations of the three major worm pests, corn earworm, European corn borer and fall army worm, build during summer and peak around Labor Day. To protect the ears from them, put a couple drops of vegetable oil on the silk six days after it appears. Plant wind-pollinated corn in blocks of six rows of six plants so that pollen from the tassel lands on the silk, says warm season veggie expert Peter Nitzsche, RCE Morris County Agricultural and Resource Management Agent.

Warm Season: around mid-May

Most people can grow a decent tomato crop. To start indoors, grow seedlings on a sunny windowsill or under fluorescent lights as close as possible without touching to get stocky growth. "Research shows that brushing the plants back and forth once or twice a day to simulate wind can make more compact growth," says Nitzsche. When tomato plants start to fruit, they are susceptible to two leaf fungal diseases that kill them from the bottom up: early blight and grey leaf spot. To prevent disease, rotate crops every year because spores over-winter. Stake the plants upright and keep the leaves dry. Water from below in the morning so the plant dries out. Remove debris from garden but not to the compost pile . "Diseases are the limiting factor," says Nitzsche. Though phosphorous is in the soil, it's often not available to plants in cold soil and a deficiency shows as purple leaves. So Nitzsche recommends giving liquid fertilizer at transplant time. Some tomatoes are known for cracking, especially big juicy heirlooms. "The more water, the bigger the fruit and the more likely it is to crack because the skin is thinner. We preach moderate watering. The idea of backing off on the water is somewhat just concentrating the sugars in the fruit instead of diluting them with water," Nitzsche says. Have patience now. Tomato plants get cold below 50 degrees. The flower buds get affected and the fruits get cat-facing and zipper scars.

With tomatoes, eggplant and peppers, commercial growers use black plastic mulch to warm the soil and give them a kick start. Remove it during hot weather or you will fry. Trial results on red plastic are inconsistent--some show higher yields, some not. "The idea is it reflects photosynthetic light into the canopy of the tomatoes and makes them grow faster. However, as the plant grows faster, it covers the plastic quicker and sometimes we don't see a yield advantage." Growing indeterminate (vining) varieties on poles and cutting off the suckers to let in more light might keep them growing faster, but with fewer stems that would produce fruit. With more sun on the plant, be careful of sun scald on the fruit. Solution: Leave two main stems to shade the fruits, more if you like smaller tomatoes. Prune a vigorous variety more than a less vigorous one. Prune a later season variety more than early ones.

squash borer
Squash vine borer killed the squash plant on the right.

Squash vine borer (moth larva) is a common problem for summer and winter squash. Once in the vine it's hard to control. Monitor the base of the stem for sawdust or holes to catch it when it first gets in before the plant wilts, then slit open the stem and kill the borer. Cover transplants with floating row covers to screen out moths and remove it when the plant starts to flower so that bees can pollinate the plant. Usually the moth flies early in the season, so also plant a later succession. If you spray, spray the stem early before the borer gets there. To kill squash bugs, place boards near squash. In the morning lift them, handpick the bugs and "squash" them or drop in a bucket of soapy water. Clean up plant debris.

Plants and Bugs

Torenia, Mexican sunflower, attracts bumble bees.

Many flowers and herbs attract beneficial insects (predatory carnivores) that eat insect pests (herbivores) on vegetables. Herbs with many small flowers, such as coriander and dill, provide more nectaries and pollen in a given space and keep predators around after they've eaten the bad bugs (their favorite food) until the next ones appear. Annuals work best because they bloom all summer.

What insects eat cabbage worms? "An array of small parasitic wasps," says Joe Mahar, Vegetable IPM (Integrated Pest Management) Program Coordinator, NJAES, for the state's vegetable farmers. "A lot of them lay their eggs in the eggs of the different moths and pest insects. We encourage the situation where parasitic moths thrive because if you can keep the adults in the area with a food source, then that greatly increases the odds with parasitic wasps attacking the egg masses of a pest." Mahar has done research with coriander, dill and buckwheat to help hold predators and parasites in plots and found they work well. "We thought we'd attract parasitic wasps, but when the study was completed we found we had increased the number of lady bugs and green lacewings and other insects that don't rely on the nectar necessarily. There's confusion on what beneficials feed on, for instance lady bug adults and larvae feed on plant pollen when there's a shortage of aphids. They prefer aphids but when aphids aren't present, they can survive on pollen."

Two good reasons to know garden bugs: don’t confuse bad bug tomato hornworm (left) with good bugs monarch caterpillar (center) and black swallowtail caterpillar (right), aka parsley worm. Instead of killing the black swallowtail butterfly larva, just plant a few extra parsley plants–some for you, some for the swallowtail larva. Photos © Peter Nitzsche, Rutgers NJAES

Parasitic wasps have several strategies. Some lay their eggs inside prey eggs and when the wasp egg hatches, one of the wasps will consume the pest egg and complete its development within the egg, then emerge as an adult wasp. Larger parasitic species insert an egg into the insect prey's body. When the egg hatches, it feeds on the internal organs of the insect. The insect remains alive for awhile. Once the wasp larva gets close to maturity, it kills the host and either exits the host body or stays within it and forms a cocoon. Sound a little like the movie X-Files? "It's kind of a nightmare world, in a sense, for insects," Mahar says.

flea beetles
Three common eggplant problems: spider mites on leaves (wash or spray with insecticidal soap); flea beetles (above) that chew holes in leaves (grow plants under floating row covers or use insecticide such as hot pepper wax); verticillium wilt that causes death with high soil moisture (rotate every year).
Below: Lady bugs eat aphids.

Gardeners can buy lady bugs, lacewings and wasps for their gardens. "As long as you have aphids in your garden, they'll stay there," says Mahar. "But once you run out of a food supply, unless you've got a lot of these other plants that produce the pollen that they feed on and off, these lady bugs will just take off and go to the neighbor's place."

But keep an eye on those predators in your garden. Lacewing larvae and adults eat aphids, but larval lacewing are voracious carnivores and will eat any insect it encounters and can overwhelm. And the praying mantis? Most people think it's a good bug, but that's not the whole truth. They eat anything they can catch including lady bugs, bumble bees pollinating and hummingbirds sipping nectar. Is it ok to kill praying mantids? "The answer is always 'yes,'" says Mahar. They have been known to hang around hummingbird feeders. Psst-- It's not illegal.

So start your vegetable garden today for the best tasting and nutritious food you can eat. And plant a row of herbs or flowering plants around each plot of veggies. It's not only beautiful, it works.

Check Rutgers Garden Information and Research for more information.
This story was first published: Spring, 2012
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