August garden checklist

UNIVERSITY OF MINNESOTA EXTENSION - www.extension.umn.edu

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Mystery of the month

What can cause maples and other trees to have already started turning color and dropping leaves in early August?

Find the solution to our mystery at the end of this article.

Pests and diseases

Seeing blossom end rot on your tomatoes? There is nothing you can do to correct the issue on the affected fruits, but you can prevent future fruit from succumbing to the calcium deficiency issue.

Calcium only moves through a plant when water transpires from the leaves. Usually, there is enough calcium in the soil, and the primary reasons for it not getting to the fruit are:

• irregular watering,
• poor air flow, and
• excessive root injury.

Make sure you are regularly watering your tomatoes, as well as giving them proper air flow by pruning lower leaves.

Find solutions to common tomato disorders.

Trees and shrubs

Water and mulch newly planted trees and shrubs.

If you lost trees to storms this summer, you can plant new ones around the same area as the old ones. Where you place new trees and shrubs will depend on the new species’ final sizes and where the root systems of the original plants are located in the ground.

You may be able to plant 3 to 6 feet from the lost tree’s stump, although in some instances you may need to plant over 10 feet away from the original tree.

You can search for plants that fit your specific site conditions in the Plant Elements of Design plant database to find replacement tree options. See our list of select trees and shrubs for Minnesota landscapes.

Flowers and other garden plants

Divide overgrown herbaceous perennials that have already bloomed this year, but wait to divide plants like perennial mums that bloom in fall until next spring.

Dig around the entire base of the plant, lift the plant out of the soil, then use a sharp spade or shovel to cut the plant into 2 or more clumps. Bury the clumps to the same depth that the original plant was planted at.

Learn more about how and when to divide perennials.

Houseplants

Continue to water and fertilize houseplants this month.

Be prepared to bring in cool-temperature sensitive plants like orchids if nighttime temperatures start to drop below 50°F near the end of the month.

Lawn

Do not mow drought or heat-stressed turf. If August experiences a drought or temperatures more than 85°F, wait until stress is reduced with either returning rainfall or cooler day and evening temperatures.

Stressed turf likely isn’t growing very much anyway, but mowing a lawn that has grown beyond normal mowing height is still preferred over further stressing the plants.

Other tasks

Harvest regularly to keep your vegetable and herb plants productive. You may see more wasps around your garden if you leave fruit on the plants to rot.

Make sure you are properly harvesting and storing home garden vegetables.

Watch this YouTube Hort Short on pinching-back basil.

Solution to the mystery of the month

A couple of things may be contributing to a tree prematurely dropping leaves. The first thing to consider is whether the tree is a cultivar that naturally turns color sooner than others. If this is the case, there is nothing you need to do other than appreciate the early fall color display.

The second thing to consider is the potential stress the tree has been under in the past few years. Stress encompasses a range of abiotic and biotic factors, including drought, flooding, mechanical injury, disease, and insect damage.

Trees exposed to a single stressor or multiple stressors at once or in succession may drop leaves immediately following the event. Some may lose leaves much later than the original event occurred.

If your trees have experienced flooding, read through how to manage flood damage to trees.

This maple naturally turns color sooner than others.

This maple tree has had extensive mechanical damage to the right side of the trunk, causing some leaves to turn color and drop prematurely.