Gardening techniques that beat the heat

Published 12:00 am Friday, May 31, 2019

By Michael O. Fine

Rowan Cooperative Extension

Pheww, that was a hot week. Temperatures in the mid-90s, humidity about the same, and dry.

Though most farmers, while still shaking off the rainiest season on record, are not yet at the point of asking for more rain, a little in the forecast wouldn’t hurt. Though our first heat wave arrived earlier than average, the effects on plant life and human morale followed the same routine.

Upon the initial exposure to high temperatures, we slump over, move a little slower and pout a bit. Then the nighttime air rejuvenates people and plants and they perk-up and remember it’s summertime, that wonderful time of year in the Carolinas that we longed for the past five months. That is the nice thing about our foothills home, by the time we grow tired of one season, another one replaces it.

Alright, let’s get into the garden and think about what we are experiencing this month. Volatile, cool-weather crops like lettuce, turnips, spinach, cilantro and such took a hit this week as insects and heat collided to destroy the foliage on these plants (insects always seems to attack bok choy, and sweet salad turnips before accompanying brassica plants and lettuces).

Mature greens, cabbages and broccoli withstood the temperatures, but required some additional water. The same applies to the summer vegetable plants such as squash, cucumbers, peppers and tomatoes. Most all the plants we cultivate for food required some additional water this past week.

Here are some strategies to help you apply water efficiently and lower temperatures in your gardens.

  • Drip irrigation: Drip tape is sold through various irrigation suppliers and is offered in commercial and home-scale roll sizes. Drip tape is connected to a main supply line at the end of a garden or field and travels the length of the row. Drip tape is made of a thin polyethylene plastic tubing (usually 3/8 inch to 1/2 inch interior diameter) with water-emitting holes every 6-12 inches (depending on the product specifications). When the pressure is applied to the supply line, each line of drip tape will pressurize and slowly trickle droplets of water directly to the soil at the base of the plants. To effectively deliver water to plant roots, set transplants or direct seed adjacent to the drip line.   The benefits of this type of watering system include:

• Watering only your desired crop row, and not the weeds in the middle of the row.

• Limits excess water on the foliage of your plants which can create a humid environment around the plant and breeds disease and fungus.

• Watering manpower and physical effort drop dramatically. With a small, upfront investment at the beginning of your season, you can lay out a simple drip system and water your garden uniformly with the turn of an outside faucet for months to come.

  • Overhead micro misters: For those folks who are trying to sustain cool-season crops into the hotter months, many micro-misters are available on the market that deliver a fine mist of water onto the foliage of the plants during the hottest hours of the day. This works well for cooling the surface of leafy greens and lettuces. Most irrigation suppliers offer fittings and attachments for micro-misting kits that conform nicely with an existing drip systems. Keep in mind, overhead irrigation can be overly applied and can create a humid micro-climate around the wet plants. To mitigate these negative effects, overhead irrigation intended to cool plants down should be conducted in the afternoon as temperatures peak and begin to drop. Also, set up an automatic timer to come on once every 1/2 hour for a short amount of time (45 seconds). Short, but frequent intervals can help limit the amount of water saturating the garden while supplying plant foliage with a cooling mist.
  • Shade Cloth: Shade cloth is sold in various densities that refer to the amount of sunlight that is blocked. Commonly for vegetable plants, a 40%-60% shade cloth has been proven to be adequate. Shade cloth is not only used to manipulate the micro-climate underneath it for temperature reduction, but also to protect warm-season fruits, like tomatoes, from sunburn and blistering. An easy structure to support shade cloth can consist of 1/2 inch PVC hooping. Simply anchor the hoops using stakes or rebar. Clamps or zip-ties work well to attach the shade cloth to the PVC hoops.

All in all, the hot weather can be our friend in the garden as plants shift to a highly productive gear. As horticulturists, we strive to find ways to harness the power of the sun and hot temperature while mitigating their extreme negative effects.

Upcoming events and reminders:

June 1 and 2 — Rowan County Art and Ag Tour. Visit for a complete list of farm stops and tours.

June 13 — Big Dreams, Small Farms: Market Garden Workshop and Farm Tour – Registrations is now open. Visit:

Saturday, 8 a.m.-noon — Salisbury Farmer’s Market:  Lots of variety is in season and farmers in Rowan County are delivering the freshest food on the marketplace. Don’t settle for less while the getting is so good.