We’ve all seen it. Wilted, scorched plants that were fine yesterday and goners today. Scorched by the sun and heat of June. Luckily there are things we can do to help our gardens through the torment of low to no humidity, hot, dry winds, and scorching temperatures.
Plants come with built in evaporative coolers. As they breathe in carbon dioxide through their pores, they release water vapor at the same time. This brings down the leaf temperature while also supplying the plant with water and nutrients from the roots in the soil (a.k.a. evapotranspiration in plant nerd language). Keeping the soil moist during the hottest part of the summer is critical. Without ample water at the root zone, the plant can’t transpire, and the water balance is lost. Because of hot and dry conditions, most plants close their pores (stomata) to prevent transpiration in order to conserve moisture in their tissues. When pores are closed, they can’t draw water efficiently through their roots, and they can’t get the carbon dioxide they need for photosynthesis, resulting in slow or stunted growth. In evening or early morning plant pores open when there is higher humidity and cooler temperatures. So watering in the evening or early morning prevents water loss through evaporation and makes more water available to the plant.
No one wants to waste water, especially here in southern Arizona. To make the most of the precious water we put on our gardens, it’s important to do a few things. First is mulch, mulch, mulch. For one thing soil is dark. Dark colors absorb heat. Light colored mulch will help reflect some of that heat. Apply thick layers of mulch. By thick I mean eight inches or more of straw, leaves or other lofty materials, four inches of heavier composted stuff. It will cool the soil and roots, keep the soil moist, reduces water run-off, and help control weeds. It adds texture, structure and nutrients as it decomposes and nourishes countless microorganisms that play a role in the water and nutrient availability to plants. As I’ve said before, don’t mix it into the soil unless it’s properly composted or you will end up with nitrogen deficiency (more on that in July’s article.) Mulch in the form of weed cloth that is water permeable is also a fine choice, though you should add some compost or straw on top to cool it down. Even newspaper works if you use at least 8 layers.
Water deeply and less often. Sprinkling gingerly over your plants with your garden hose or sprinkler will only waste water in the long run. Water needs to penetrate deeply to the root zone. Let it run low and slow to minimize run-off. The best choice, if you can, is to install a drip irrigation system. It can be as simple or complex as you want. There are many inexpensive choices available now that simply screw onto an existing faucet complete with timers and are battery operated. They’re not complicated and everything you need to install one is available at any home improvement store.
What to plant in June: Continue planting tomatoes, peppers, eggplant, pumpkins, squash, melons, corn, beans, and pretty much any heat loving crop. We still have a long growing season ahead, so get growing! As always if you have any questions or comments, I invite you to email me at firstname.lastname@example.org If you need starter plants for your vegetable garden email me to visit my greenhouse or find me @patagoniaplants on social media.