PHOTO: Susy Morris/Flickr
Margaret A. Haapoja
August 24, 2016

By midsummer, our gardens have reached their zenith. We can almost watch our squash vining, tomatoes ripening and corn stretching for the sky. While we begin to enjoy the fruits and vegetables of our labors, plenty of work still needs our attention. Most of the chores during this part of the growing season are in maintaining the garden’s appearance and good health.

Weeding, Spacing, Pruning, Staking

Frequent and shallow cultivation is the best means of weed control, according to Bob Olen, University of Minnesota extension educator. Cultivating serves two purposes: It loosens the soil, allowing air and moisture to circulate around the crop’s roots, and it controls weeds. Beginning as soon as plants are recognizable, cultivate lightly, loosening the top 1/2 inch of soil. It’s best done early and often so the garden looks good and the plant can grow without competition. Weeds vie for water and nutrients.

My husband has fabricated a handy tool he calls “the weeder.” He simply attached a loop of 1- to 1½-inch steel banding to the end of a broom handle. Every few days, he walks through our vegetable garden wielding the weeder. It’s much easier on the back than bending to pull weeds, and it loosens the soil, easing the way for air and moisture to circulate around a crop’s roots.

If every seed sown in the vegetable garden were guaranteed to germinate, we could sow single seeds at predetermined intervals along a row and thinning would be unnecessary. Because no such guarantee exists, it’s common to sow many more seeds than needed and then thin the row after germination. Yanking healthy seedlings out of the ground goes against the grain for most gardeners, but it must be done, because crowded seedlings grow into miserable, leggy, unproductive plants. Thinning is easier after a rain when the soil is still moist and the unwanted plants slip from the soil with a minimum of disturbance. If there hasn’t been a recent rain, water your garden the day before you plan to thin your crops.

Vince Fritz, director of operations at the University of Minnesota North Central Research and Outreach Center, thinks that putting things too close together is one of the biggest mistakes gardeners make.

“It looks great in June, and in August, it’s a jungle,” he says. “Radishes, for example, you can control based on just putting in so many seeds per linear foot.” Most seed packets spell out this information for you.

Although it goes against my conservative nature to uproot healthy seedlings, carrots should stand 1 inch apart in the row to do their best. Beets and parsnips should be thinned to 2- or 3-inch intervals, and kohlrabi plants should be 4 to 6 inches apart. Another way to eliminate having to thin thickly planted rows is using pelleted seed or seed tapes.

Fritz also emphasizes the importance of pruning tomato plants regularly.

“A lot of gardeners will forget to pinch off the suckers—those shoots that grow out from the axil between the main stalk (leader) and leaves,” he says. “So now you’ve got this beautiful tomato bush trapping a lot of nutrients and moisture, and it delays flowering. Those suckers should be pinched off just as they’re starting to grow. One of the ways we can encourage timely fruit set is by pruning the tomato plant down to one or two main leaders.”

Caging or staking tomato plants does two important things: It keeps them from rotting because they are vertical rather than in contact with the soil horizontally, and it helps prevent or minimize foliar disease because the foliage won’t be wet.

Harvesting, Watering, Mulching, Fertilizing

PanAmerican Seed vegetable business and product manager Josh Kirschenbaum describes midsummer as when crops start to become harvestable.

“Keeping on top of the harvest is really important as well as exciting because that means all the work you’ve done prior to midsummer is starting to pay off,” he says. He side-dresses with some natural fertilizer to give the plants an extra boost in midsummer. “If you regularly harvest fruiting vegetables, such as tomatoes, squash, peppers, the plants will continue to produce.” Olen harvests spinach, lettuce and radishes early and on a timely basis but stops harvesting rhubarb and asparagus by the Fourth of July.

Watering is critical.

“Typically a vegetable garden at full throttle needs a good 1½ to 2 inches of water a week, especially when crops go from a vegetative to a reproductive state—plants going from green leaf tissue to flowering and fruiting, like peppers, squash and broccoli,” Fritz says. “Good continuous moisture supply is really important, especially on sandy soils.” He uses soaker hoses rather than overhead watering to minimize foliar wetness and prevent foliar disease. Trickle irrigation uses less water than most other forms of irrigation.

Water early in the morning on a sunny day to allow the foliage to dry and minimize the amount of water lost to evaporation. If you wait till midday when the sun is hot, you lose much of the water. If you irrigate late in the day, you run the risk of the plants going into the evening with wet foliage, which invites disease. Whenever you water, do so for fairly long periods so the soil is well-soaked occasionally rather than lightly moistened frequently.

Watering is never more important than during a plant’s first days in the ground. If newly sown seeds dry out, they will not germinate; if newly emerging plants, which lack the root structure to delve deeply for moisture, dry out, they die. It’s especially critical that carrot seeds be kept moist until they germinate. Vegetables planted in containers need to be watered every day in summer.

Mulches keep the soil moist and cool, conserve water, present a neat appearance and cut down on weeds. Wood chips, shredded pine bark, pine needles, grass clippings or shredded leaves are possible choices. Try to keep mulch about 2 inches from plant stems, and remember that mulch depletes nitrogen from the soil as it decays, so some additional fertilizer will be required.

Midsummer is a good time to do a soil test and fertilize as recommended.

“Whatever the nitrogen recommendations for a crop are, do a split application,” Fritz says. “Apply 50 percent of the total nitrogen needs to the crop at transplanting time, and the other half about four to five weeks after that so you are not losing the nitrogen from rainfall.”

Many plants benefit from the addition of some type of fertilizer to give them a boost in midsummer. For instance, I side-dress all brassicas every three to four weeks during the growing season with a balanced fertilizer, such as 19-19-19, at the rate of about 1/2 pound to a 10-foot row. I scratch fertilizer into the soil on either side of the row and water to dissolve it and make it available to the plants. Cucurbits also need side-dressing, as do tomatoes and peppers.

Plant More

After harvesting early-maturing vegetables, such as salad greens, radishes, peas and spinach, gardeners can plant other crops in midsummer for a fall harvest. It’s important to know the average first frost date in your area in order to calculate when to plant late vegetables so they’ll mature before being killed by cold weather.

Lettuce you can plant later in the summer because it will have less danger of bolting, and you will still get a fair amount of yield out of it,” Fritz says. “Plant it in a partially shaded area.”

He says all brassicas are less bitter and tend to be sweeter when planted to mature in the fall.

Olen plants romaine lettuces in midsummer since they are more heat-tolerant than leaf or buttercrunch types. He harvests the main heads of broccoli to encourage development of the side shoots. Iowa gardener David Cavagnaro plants fall-heading Chinese cabbage and other mustards, a late crop of cucumbers and summer squash in early July. He plants fall lettuce and cilantro at various intervals through the summer.

Steve Bellavia, who works on crop production at Johnny’s Selected Seeds in Maine, does succession planting of beans, lettuce, beets, Swiss chard and radishes in midsummer.

“Too many gardeners only plant a crop once or twice rather than multiple times,” he says.

Pest Patrol

Cavagnaro increases policing for mice and voles in midsummer.

“They love the lush midsummer cover and developing root crops, such as sweet potatoes, beets, carrots and winter squash,” he says. “Voles must be killed with rat traps, not mouse traps, set with chunks of carrot and covered from above.”

Cabbage, cauliflower and broccoli all face the threat of the cabbageworm caterpillar, a green worm that riddles the leaves with holes and hides in the broccoli heads. To protect against this pest, Fritz uses plant protectants rather than pesticides and insecticides.

“Physical barriers such as Reemay or floating row covers work well on the brassicas,” he says. “They are semipermeable to wind and water gets through. They’re expensive, but home gardeners can rinse them off, sterilize them and reuse for several years. Use a row cover like that if you really want to have an organic garden. However, if you’re seeing butterflies, there are probably eggs already, so if you put a row cover over it, those eggs will hatch and those caterpillars will have a wonderful party.”

University of Minnesota Extension horticulturist Cindy Tong uses low tunnels with sparkly netting for insect and rabbit deterrence. “The sparkly part is probably acting like reflective mulch that can repel some aphids,” she says.

Fritz adds that there are organic products you can use. “Bacillus thuringiensis comes in different applications, and it works,” he says. “If you have a rain, you have to reapply because it doesn’t have long-term residual effect.” He also suggests peeling off the outer leaves of cabbage. “It depends on what you’re after,” Fritz says. “Do you want an absolutely gorgeous garden you can showcase, or are you really after the productivity of the garden?”

This article originally ran in the July/August 2015 issue of Hobby Farms.


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