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Garden Help Desk: Tips for successful autumn tree-planting

By USU Extension - Special to the Daily Herald | Oct 7, 2023
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A wide, but not deep, planting hole makes it easier to safely remove burlap and wire baskets.
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These tree crickets were paralyzed by a female wasp and then used to provision a nest of grass clippings where she laid her eggs.

Fall is here, and some gardeners may be hoping to plant another tree or two before the end of the season. If you’re part of that ambitious group, I have good news for you. Fall is a great time to plant trees and shrubs! Cooler weather means less stress for trees, shrubs and gardeners.

Let’s assume you already have the trees you’re going to plant. You’ve chosen varieties that are well-suited to our area: tolerant of alkaline soils; cold, dry winters; and summers that are hot and dry. You’ve also chosen a planting site that will give your trees the sunny hours they’ll need each day.

Now that you’re ready to plant, here are some reminders for giving your trees the best start in their new home.

When you plant your tree, make a bowl-shaped planting hole at least twice as wide as the root ball of the tree you’ve chosen, but make sure the hole isn’t any deeper than the root ball. The top of the root ball should be at the same level as the soil surface or slightly higher.

It’s important that your tree isn’t planted too deeply, as that will shorten the life of your tree. Brush away the soil on the top of the root ball until you see the trunk-root flare, the place there the trunk and the true roots meet. That is the top of the root ball, and you’ll measure from there to determine the depth of your planting hole.

Protect the root ball of your new tree. Handle the tree by the root ball, not by the trunk so that the weight of the root ball doesn’t break away any roots. If the root ball is balled and burlapped (in a metal basket and burlap), remove as much of the basket and burlap as possible once your tree is positioned in the hole and the trunk is straight. The wider the hole, the easier this will be.

Backfill the planting hole with the same soil that you dug out. Don’t mix in compost, potting soil, soil conditioner, manure, sand or other soil amendments. Mixing in soil amendments will increase the risk of poor drainage and also discourage the roots from growing out into the surrounding soil. Water when the hole is half full to settle the soil and eliminate any air pockets, then water thoroughly after you’ve finished backfilling the hole. Do not fertilize the tree. Cover the planting area with a 3-inch layer of an organic mulch such as bark nuggets or shredded bark.

Overwatering has serious consequences for trees, and fall-planted trees usually don’t need to be watered twice a week like trees that are planted in the spring and summer. But they still need to be watered deeply more often than established trees in your landscape.

The weather is cooler, and trees will begin dropping their leaves and using less water. Pay attention to the weather, monitor soil moisture and water deeply when the upper few inches of soil seem dry. If you’ve planted an evergreen, you’ll want to give it a deep soak before the ground freezes. Late November is a good time to do that.

Can you please identify this? I know I’ve seen them before and I know how to treat it, I just don’t know what to call it. They look like a lacewing with grasshopper legs and they pack grass into doorways and window sills to lay eggs in.

These look more like tree crickets, victims of the nest builder.

The nest builder is most likely a grass-carrying wasp. They lay their nests of clipped grass blades in hollow stems, crevasses, abandoned bee nests, window tracks and similar snug locations. Grass-carrying wasps are skilled predators of other insects and beneficial pollinators. The larvae feed on the paralyzed tree crickets that the wasp puts into the nest when she lays her eggs, but the adults feed on nectar and pollen. They aren’t aggressive and don’t sting unless handled or harassed. Chemical controls are not recommended. The best control for this wasp is to simply remove the nest, which you’d need to do anyway.


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