Hot Weather and Plants

Drought in a lawn
Drought lawn photo from John Fech, Nebraska Extension Educator in Douglas/Sarpy Counties.

It’s hard to say what normal Nebraska weather is. However, this year has been particularly difficult for our plants. The quick change from cool to hot has caused some lasting effects on our plants. Some of the common problems we have been seeing this year include: leaf scorch, drought problems, and poor pollination.

Leaf Scorch

Leaf scorch can happen on the leaves of our trees, vegetable plants, and other garden plants. Leaf scorch causes the tips of leaves of many plants to turn brown and crispy. The abrupt change in our environment from cold to hot and humid left even the most well-adapted plants struggling to stay green. Even plants that are not in full sun will be affected from the high temperatures, such as hostas that are planted in shade.

When the plant is unable to take up enough water, the leaf tissue that is farthest from the major veins will dehydrate first causing leaf margins to scorch first. Leaf scorch is not necessarily caused from lack of water, it is because the plants cannot take in enough water to compensate for what is being lost through transpiration. The moisture may be present around the roots, it just is not entering the plant as fast as it is leaving it.

Do not automatically go out an water the plants that are showing scorch. Watering may be necessary, but don’t overwater. Ensure that the plants have mulch around them and check the soil moisture before watering.

Dry Conditions

In these dry conditions we have faced through most of the growing season, it is important to remember to water your plants. But, it is always a good idea to check soil moisture before watering to help reduce the problems with overwatering. Most of our plants need about 1 inch of water per week, if they don’t receive that from precipitation, they need it from irrigation. If a screwdriver or dowel pushes into the ground easily moisture is sufficient around the plant. For trees the screwdriver should go down 12-18 inches, for perennials it should go down 6-8 inches and for turf and vegetables it should go down 4-6 inches.

Poor Pollination

The heat we are facing is also causing some slight problems with poor pollination and there are problems we could face later as our fruits begin to develop, abnormally. In this heat there is a condition called blossom drop that can occur. It is when the flowers abort and fall from the plant rather than developing into a fruit. This can also be due to drought conditions, which we are also facing. When temperatures reach 93 degrees F, pollen becomes sterilized, so even if they get pollinated, they are not fertilized and fruits will not develop.

The heat and drought we have been dealing with can also cause small fruit development and sunscald. Sunscald happens in high temperatures when our fruits develop without leaf cover. Don’t prune tomatoes too heavily or it can leave your fruits open to damage from sunscald.

We could also have problems with bitter tasting cucumbers this year. Cucumbers produce a chemical called cucurbitacin, which is bitter in flavor. Most cucumbers that we eat now have low amounts of this chemical, but they can produce more due to environmental stress. Uneven watering, drought issues, and high temperatures can all lead to the build-up of cucurbitacin. It is likely this year we may have a problem with that, and there is no way to fix it. Just be sure to try out your cucumbers while you are cutting them up for your recipes.

The leaf scorch information for this article came from Kathleen Cue, Dodge County Extension Educator.

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