Dealing with Dry Summers in the Vegetable Garden

July and August are typically dry months in New England with days, often weeks, between significant rains.  This year is no exception as our Ellsworth garden has not received a good soaking for over two weeks while temperatures hover around 90 degrees.  We have been the “hole in the doughnut” as afternoon or evening thunderstorms irrigate gardens all around us.  I’m spending a lot of time dragging the hose and spreading a three- to four-inch layer of shredded leaves, collected last fall, on every exposed patch of soil.

A friend who gardens in the Berkshires of western Massachusetts is also complaining about the lack of rain.  He used the word “drought” in a recent email, warning me that his garden may looked stressed when I visit at the end of July.

While “drought” may not fit the current situation, at least not yet, this dry spell could not come at a worse time for many vegetable crops.  Tomatoes, peppers, and eggplants need water most during flowering and fruit set.  The same can be said for beans, cucumbers, summer squash, and winter squash.  Potato tubers will be knobby if they are deprived of water in mid-summer.  Carrots and other root crops need a consistent supply of water through the summer, as do onions with their limited and inefficient root systems.

There are several cultural practices that will maximize the efficiency of water use while minimizing the amount of time spent irrigating vegetable crops in summer.  Some of these practices can be implemented immediately, others will take more time.

Amend your garden soil annually with course decomposed organic matter

Course organic matter in the soil acts like a sponge, absorbing water and holding it in the root zone.  Use compost made from manure, never fresh manure, to build a water-holding soil. Do not use wood chips or bark, as these will deplete soil nitrogen during the growing season as they slowly break down.

The addition of fully composted manure to the soil should be done at least four months prior to harvest of any edible crop.  We use goat manure that is windrow-composted for several weeks by the farmer before we purchase it in early fall and haul it by the pickup load to the back of our garden.  We continue the composting process in a tarp-covered pile through the winter and early spring, finally digging it into the beds when the soil can be worked.      This composted manure, along with annual incorporation of the shredded leaves or straw used as summer mulch, keeps the organic content of the soil high.

Mulch, mulch, mulch…

Organic mulches minimize evaporation of water from the soil, reducing irrigation frequency by as much as 50%.  Apply a three- to four-inch layer of mulch in early summer, after soil temperatures have settled in the 60s.  Use mulch materials such as straw or shredded leaves, materials that will decompose over the course of the growing season and help sustain soil organic matter content.

Avoid using bark or wood chips, except in walkways.  They take a long time to decompose, robbing plants of nitrogen in the process.

Handled properly, lawn clippings make an excellent mulch.  Apply fresh clippings in 1/4-inch layers, allowing each layer to dry before adding more.  Do not use clippings from lawns treated with herbicides or other chemicals, and avoid using grass clippings collected when the grasses and broadleaf plants in the lawn are setting seeds.

I realize that use of grass clippings as a vegetable garden mulch goes against the grain of sustainable lawn care, i.e. clippings should be left on the lawn to decompose, returning nutrients to the soil.  But for many of us, the “lawn” is a patch of mixed grasses, dandelions, plantain, and other plants that must be mowed a few times during the summer to look tidy, but will be converted as soon as possible to more raised beds for growing vegetables.

I often compost our “lawn” clippings, except when any of the grasses or other plants are setting seed – seeds have a way of surviving the highest compost temperatures.  I layer the clippings in the compost bin with composted manure, seaweed, kitchen vegetable waste, and spent garden plants, then use the finished compost as a mulch.  Nothing jumps start a cool compost pile better than green mower clippings!

Plant in blocks, rather than rows

Sow seeds and plant seedlings in blocks (wide rows) rather than narrow rows.  As the plants grow, they will shade the soil, reducing evaporation.

Weed, weed, weed…

Unwanted plants compete with crop plants for water.  Much of our garden time in July and August is spent pulling weeds, trying to get them out when they are small.  Mulching makes this task less time consuming.

Pulling weeds will keep you in touch with the soil’s need for water.  If dry soil is pulled up with the weed, it’s time to water.

A soaker hose is an efficient way of delivering water to the root zone without wetting the foliage. Whenever possible, it should be placed beneath the mulch to maximize water use efficiency.

Overhead sprinklers are inefficient watering tools, much of the applied water ending up in walkways.  Wetting leaves with overhead watering also exacerbates the spread of foliar diseases such as early blight and late blight on tomato foliage and mildew on squash leaves.
Applying water to the base of plants, using a soaker hose, drip tubes, or a garden hose, will reduce water usage by about 50%.  Make sure that you water long enough to wet the soil to a four-inch depth.

It is late Tuesday evening and as I prepare to file this column, lightning flashes reveal the dark silhouettes of spruces on the horizon, thunder booms, and again there is the hope of rain, just enough to bring respite from dragging the hose for a day or two.  Not too much, mind you, and not every evening, or the ripening raspberries will mildew.

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About Reeser Manley

I was born in Laramie Wyoming but moved to the southeast at an early age. I was educated through my B.S. in Biology in the Columbus, Georgia area, then crossed the Chattahoochee River to earn my M.S. in Botany at Auburn University. For the next ten years, I worked as Horticultural Manager for the George W. Park Seed Co. in Greenwood, S.C. At 40 years of age, I decided to return to graduate school and in 1994, I earned a Ph.D. in Horticultural Science from Washington State University, Pullman, Washington. Fast forward through 10 years at university (7 at UMaine, Orono) and you find me teaching high school science in Eastport, Maine, the edge of the world, and writing a weekly garden column for the Bangor Daily News. My new book, The New England Gardener's Year, a Month-by-Month Guide for Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, and Upstate New York”, will be published later this year by Cadent Publishing. You can learn more about the book by visiting its Facebook page: http://www.facebook.com/pages/The-New-England-Gardeners-Year/187285218055676.)