It feels like summer has really arrived in Oklahoma this week. We have been very blessed so far this growing season with periodic breaks in the heat thanks to clouds, cool fronts and even some rain showers. This was the first week of pretty much full time, unfiltered bright sun and temperatures in the mid to high nineties every day. It looks like more of the same in the weeks ahead. Our early spring plantings have had time to get rooted in and have grown a nice plant canopy and many of our flowering annuals and perennials have been and are blooming nicely this season. Folks are harvesting their first big tomatoes, cantaloupes and even a few early pumpkins. This summer weather is a real test for many of our plants as they deal with the extreme heat and dehydration. Just like we humans need to drink more water and stay hydrated in the heat, so do our plants. Deeper rooted and more established plants like trees, shrubs and many perennials and native plants can handle the heat and water stress better as they have a larger and deeper root system that can draw in water from deeper in the ground and using a bigger network of roots as “soda straws”.
Annuals and newer plantings that have shallow roots or don’t have as well established of a root system will show the stress of the heat and dry conditions quicker and more often. We can grow lots of types of plants if we are faithful to take care of their watering needs. They can grow great corn not just in Iowa, but in Guymon, Oklahoma and even the Arizona desert as long as the growers are prepared to irrigate and provide adequate water to keep the corn from too much stress. Many plants will tolerate the high light and intense heat as long as they receive adequate water at the right times and don’t become too stressed. Some plants will visibly wilt, some turn grayish green instead of bright or dark green, and most all will begin to yellow and drop leaves so they have less plant to support if they are under too much heat or drought stress. Plants under stress become much more vulnerable to pest problems, like bagworms on needle evergreens, red spider mite on tomatoes and marigolds, webworms on pecans, walnuts and other trees. As soon as you notice these pest problems, get them identified and decide on a course of action.
Help keep your plants summer strong by mulching the soil surface around them 2” or more deep with a good bark or hull mulch. Water deeply and regularly between rains using drip irrigation, soaker hoses, sprinklers or your water hose. Every time your plants go to the wilted stage or come under heavy heat or drought stress it saps some of their energy and momentum and acts like a growth regulator. You surely don’t want to overwater your plants but you don’t want to get them “wilted” dry either. Some good gardener judgment is involved to know your soil type and water accordingly. Sandy, well drained soil will dry out more often while clay, tight soils will dry out less often. One key reason to add sphagnum peat and organic matter to our garden soils over time is that soils with more organic matter will hold more moisture and need less regular or extra watering. Don’t forget that above ground hanging baskets and container plantings will dry out quicker and will need to be watered more often.
You can still plant in this heat as long as you will be faithful in watering these new plantings. Like the stories of the cobbler’s kids being the last to get shod we horticulturists are often the last to get our own gardens planted because of being so busy serving others in spring. Dona and I have done most of our plantings the last two weeks and there may be a little sunburn and extra “heat wilting” for the first few days or even weeks as they adjust to their new home but with adequate water they will adapt well and look great as the season progresses. You can still plant as long as you will water and mulch!
Rodd's Seeds of Wisdom 