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Planting plants in the heat

Posted 4/29/2008

Many people will advise against planting landscape plants during the heat. This probably arose from the idea that there are certain types of plants that you can’t plant during the heat. These are bare root plants and prepackaged plants usually sold by mail order. To be successful with summer planting there are some precautions that you need to take. IF PLANTING HAS TO BE DELAYED AT ALL, PLACE CONTAINER PLANTS IN THE SHADE AND WATER THEM IMMEDIATELY AFTER TRANSPORTING. If they can’t be put in the shade, crowd them together so that they shade each other and their containers as much as possible. The roots of plants are very sensitive to both cold and heat. Placing the containers in the sun for just a few minutes will raise the surface temperature of the container to over 150 degrees. This heat transfers to the root ball oftentimes killing that portion of the root zone on the hot side of the container. The plant may not die but it will set the plant back and slow the time it takes to recover from planting.

Dry rootballs heat up faster than wet rootballs. If these are not desert-adapted plants, then water them twice a day while they are in their containers, once about 9 AM and again about 2 PM. If they are desert adapted, water them once a day. PLANT DURING THE EARLY MORNING HOURS. Planting during midday can be asking for trouble if you are not careful.

DIG THE HOLE 2 TO 3 TIMES WIDER THAN THE CONTAINER. It is much more important to dig the hole wider than it is to dig it deeper. Set the soil to the side. Remove large rocks but small rocks are all right. This is the soil you will be amending and then using for backfill.

CHECK THE HOLE FOR DRAINAGE. Fill the hole with water and see if it drains in several hours. In areas of known caliche or other problems that prevent good drainage you may have to plant on a mound so that you have drainage. The bigger the mature size of the plant the bigger the mound.

MIX SOIL AMENDMENTS WITH THE EXCAVATED SOIL, STARTER FERTILIZER AND SULFUR IF NEEDED. Use one shovel of amendment for every 4shovels of soil. Follow the directions for fertilizer and sulfur and mix it with the backfill soil.

CHECK THE PLANTING DEPTH. When done, the top of the soil in the container should be at the top of the finished planting hole. Place the container and plant in the hole or measure the depth of the container and the hole. When finished planting, the soil in the hole should be at the same level on the plant as the soil in the container.

REMOVE THE PLANT FROM THE CONTAINER BY EITHER CUTTING THE CONTAINER OR INVERTING THE PLANT AND LIFTING OFF THE CONTAINER. Do not pull the plant by the trunk or stems to remove it from the container. This is a sure way to kill a plant.

IMMEDIATELY PLACE THE UNPROTECTED PLANT IN THE PLANTING HOLE AND BEGIN ADDING WATER TO THE HOLE. The roots should not be unprotected for than a few minutes. Actually, feeder roots begin to die within seconds after they are exposed to the air. The water should be wetting the hole and keeping the roots from drying out. Never backfill around a plant with dry soil or plant in a dry planting hole. If you do, it will damage the feeder roots and increase transplant shock and recovery time.

AS THE WATER IS ENTERING THE HOLE, START COLLAPSING THE EDGE OF THE HOLE WITH YOUR SHOVEL, MAKING THE HOLE WIDER. ADD THE AMENDED SOIL AT THE SAME TIME. The water should be making a very wet mud around the roots. The muddy backfill will remove air pockets around the rootball. This will anchor the plant and will minimize the need for staking, if it will be needed at all. If you are doing it right, you should see air bubbles rising to the surface of the muddy backfill. If the plant is too deep in the hole, do not pull the plant up by its trunk or branches. This will rip and damage roots. Instead push a shovel under the rootball and lift it by levering it up against the edge of the hole. Or you can reach into the mud and lift the rootball with your hands. Once lifted, use the handle of the shovel or a stake and push it into the planting hole around the rootball. This will help to get the muddy backfill to flow under the plant and it will not sink back down when you release it.

CONSTRUCT A CIRCULAR WALL (BERM) AROUND THE PLANTING HOLE THAT IS 2 TO 4 INCHES TALL. Larger plants will need taller berms. This berm will be used to hold water in the planting hole when watering it in after planting. You should do this even if you are going to use drip. If you are planning on drip, you can remove the berm later after watering the plant deeply for a few days. If you are using bubblers, then you will need the berm to hold the water during an irrigation.

FILL THE BASIN SURROUNDING THE PLANT WITH WATER TWICE. This will help to get the soil surrounding the root ball wet and wash away any soil salts that might damage plant roots. SHOULD I STAKE THE PLANT? If water was used to settle the soil in the planting hole then often times staking is unnecessary. Staking would only be necessary if the plant can’t stand on its own. After the water has fully drained, gently bend the top of the plant and watch the soil in the planting hole around the rootball. Can you see the root ball moving in the planting hole? If it appears not to move, you did a good job and don’t need to stake the plant. If it does move, then I would remove the plant and the muddy backfill and replant it following the same steps. You were probably just impatient in adding the backfill and didn’t get the air bubbles removed.

MULCH THE SOIL IN THE PLANT BASIN TO HELP KEEP THE SOIL FROM EVAPORATING. Mulching is important for conserving water and weed control. Rock is a mulch too. But I wouldn’t add the rock mulch until after it has been watered in several times and the berm removed. It might look silly if you don’t remove it. Plants in lawns should have the grass removed at least 18 inches from the center of the hole to keep lawn mowers from damaging them.

IRRIGATE DAILY FOR ONE WEEK ON DESERT PLANTS, TWO TO THREE WEEKS ON NON DESERT PLANTS. After this time, gradually decrease the frequency of the watering not the amount. In other words apply the same amount of water each time you irrigate but do it less often. Try to water deeply no more than twice a week for non desert plants and from one to two weeks on desert adapted plants. Watering frequency will vary among plants, time of year and soil types. Contact University of Nevada Cooperative Extension for more information on planting or watering plants.

The University of Nevada Cooperative Extension is an outreach arm of the University that extends unbiased, research-based knowledge from the University of Nevada—and other land-grant universities—to local communities. Educational programs are developed based on local needs, often in partnership with other agencies and volunteers. For more information about the University of Nevada Cooperative Extension, please visit the website at or call (702) 397-2604 or 346-7215.

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