Keeping Plants Healthy in the Heat with Mike Darcy

June 22, 2021

Knowing the weather predictions for the coming week, I was up early this morning to get my plants watered before the heat of the day. If the weather forecast is accurate, it’s possible to have temperatures over 100 degrees. Not only can we be suffering, especially for those without air conditioning, but we need to think about our plants and what they might be going through.

Keeping Plants Healthy in the Heat Blog - Growing Onions

In my garden, I have found that many plants will have wilted leaves and yet I know there is sufficient moisture in the soil.

TIP: Some of my gardening friends place a thermometer on a window facing inside so they can glance and know what heat condition their garden plants are under.

Wilted Plant - Keeping Plants Healthy in the Heat Blog

Wilting Plants

With high temperatures (once they rise above 90 degrees), some plants may wilt simply because they cannot absorb as much water as they need. Many plants also will “curl” their leaves as a natural defense against heat. Curling reduces the plant surface exposed to the sun and helps the plant retain moisture.

Cooling with Water

While I realize that it is a temporary ‘fix’, and not extremely efficient with water, I often spray heat sensitive wilted plants with water on hot days and this will usually perk them up again. Often when plants get stressed for water, the leaves will scorch. Hosing them with water several times on very hot days will usually prevent this.

hanging basket in the sun - Keeping Plants Healthy in the Heat Blog

For me, having a watering wand is indispensable for watering potted plants. Early morning watering, also the most efficient time of the day to water, can be quite enjoyable with a watering wand in one hand and a cup of coffee in the other. I find at this time of day, it is often cool and quiet and I enjoy watching the hummingbirds already busy collecting nectar.

Keeping Plants Healthy in the Heat Blog - Planters

Potted Plants & Baskets

Potted plants, especially hanging baskets, need extra care during these hot summer days. Because they are not in the ground protected and insulated by the earth and are exposed to the dry air, they dry out more quickly than garden bed plants. I have some pots that I even need to water twice a day.

Keeping Plants Healthy in the Heat Blog - New plantings

Also, be aware that some pots, depending on the material they are made of, can become very hot and roots may burn without adequate moisture. A useful and inexpensive tool to consider is a simple moisture meter. If you are concerned over a particular plant or two, stick the probe in the soil to get a reading on the moisture level in the soil available to your plant. This can also help if you tend to over-water.

New Plantings

Any trees, shrubs or perennials that have been recently planted will also need extra water at this time. Their roots have probably not had enough time to spread and they are limited in the space they have to draw moisture from. If you have added compost, bark dust or another amendment to the soil, check to be certain that water is going through it and is wetting the earth below rather than simply running off or being absorbed by the compost. I have found that often a sort of barrier can form when these materials have dried out and water will run off the surface without penetrating into the soil. If this happens, scratch the area with a rake or hand cultivator to break the barrier and then water.

Keeping Plants Healthy in the Heat Blog - Drip Watering

Soaking & Watering

Soaker hoses are a good way to water plants without allowing much of the water to evaporate. Be sure to check them regularly to be sure they are providing water where it is needed. If you are using a drip irrigation system, which are often used for watering pots, check these constantly to be certain the flow of water is adequate. Check with your Wilco Garden Area Specialist to ask about putting together your drip system. They are efficient, cost-effective, can be placed on timers, changed over time and allow putting the right emitter at the right spot for the plants needs. Plus, they are fun to assemble and use!

artichoke in sun - Keeping Plants Healthy in the Heat Blog


Do most of your watering in the early morning or evening to prepare your plants for the hot day ahead. Watering in the morning before the heat rises during the day allows the water to penetrate further in the soil and be available for your plants during the heat minimizing evaporation.

Make use of these hot days and walk around your garden and observe your plants. Maybe there are some that are in a sunny location and would be better in a shaded area. Make notes of what might need to be moved at a later date. Gardens need to be edited constantly.


Heat waves! When temperatures soar above 100 degrees for more than a week or so, it not only affects the health of people, but also garden plants. During heat waves, extra measures need to be taken to protect the vulnerable. For humans, we buy up fans, install window air conditioners, drink more ice water, etc. If you expect that you’ll see temperatures like this for an extended time, you may want to consider adding some sun protection to a raised bed, a particular area of your landscape, or a group of potted plants that are exposed to the sun for most of the day. You can quickly set up a sunscreen cover that will reduce the ultra-violet rays by 2% providing 70% shade. All you need are a few T-Posts or other tall garden stake to drape sun-shade netting over. Voila! Instant heat protection that can be removed and reused as needed. Enjoy the sun! Protect your plants and yourself.

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