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Do’s and don’ts for hot weather gardening

Minnesota gardeners are experiencing a streak of hot weather — 90s during the day, 70s at night. This can make gardening challenging for plants — and gardeners. Here are some do’s and don’ts for gardening and lawn care during hot and humid weather.

Watering can pouring water on root area of a woody plant in a pot.
Apply water to the root zone of plants

DO water plants early in the morning - and don’t forget your trees!

  • Applying water to plants before the really hot temps occur allows soil to absorb the water and reduces evaporation.
  • Always apply water at the base of the plant (the root zone) whenever possible to reduce the chance of leaf disease and other soil-borne pathogens affecting your plants.
  • For more watering tips see how you can Water Wisely.

DON’T apply herbicide.

  • Herbicide can become volatile (turn to gas) when applied during extreme heat. The gas can drift and harm non-targeted plants.
  • Product labels will indicate safe temperatures for application.
  • Always follow the label of any pesticide.
  • In the meantime, Remove insects and weeds by hand or using a weeding tool.
  • Read about Avoiding herbicide drift.

DO deadhead flowers.

Gloved hand holding pruners ready to cut just above a leaf and remove a dead flower.
Cut just above a leaf when deadheading flowers

Deadheading means cutting off spent flowers. Once a flower dies, a plant will use a lot of its stored energy to produce a seed head. By removing flowers after they bloom, the plant will use energy for leaf, stem and root development instead of seeds. You might even get a second bloom!

University of Illinois Extension has more information on Deadheading flowers and spring bulbs.

DON’T cut your grass as often.

During the hot month of July, our cool-season lawn grasses become dormant meaning they slow down their growth rate due to high temps. Mowing 2 to 2.5 inches can stress grass plants and remove too much of the grass blades that shade grass plant crowns and reduce burn-out (when our lawns become brown).

Mow your lawn higher — 3 inches or more — to leave more green grass for photosynthesis and to shade your grass plants from the hot summer sun.

Mowing practices for healthy lawns has advice on how to keep your lawn healthy in any situation.

Green lawn turning brown.
Lawn stressed during a hot, dry summer

DON’T fertilize your lawn.

Fertilizing during this time of slow growth can force grass plants into active growth — something you want to avoid during hot weather.

  • Keep your lawn watered and give it a break during hot weather.
  • Temps will cool down in August and grass plants will start growing again.
  • The Minnesota Lawn Care Calendar shows the best time for lawn care tasks throughout the year.

DO water containers.

Plants growing in pots, planters, and other containers will dry out quickly in the heat.

  • Water early in the day so water can soak in and be absorbed.
  • Your plants may wilt in the midday heat, but if the soil is still damp, they will recover once out of the sun. This goes for the plants in your garden beds too.

DO avoid heat stress!

  • Drink beverages that contain electrolytes, wear sunscreen, a hat, and gloves that breathe.
  • Take breaks indoors or in the shade where you can cool down.
  • Keep an eye on the people around you for symptoms of heat-related illnesses and don’t hesitate to call 911.
  • The CDC has information on preventing and detecting Heat Stress Related Illnesses.

Stay well and garden well!

Julie Weisenhorn, Extension educator, horticulture

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