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Sugar maples are big, easy to grow, and provide great fall color. Photos by Doug Oster

Gardening Green with Doug 

A Chill Is In The Air — Tips on Fall Planting

By Doug Oster

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September 13, 2024

It’s the first morning with a real chill in air, a slight breeze gently sways the tops of the tomato plants. Along with peppers, beans, cucumbers, and annual flowers, the summer garden begins a slow decline. As all these plants hang on until the first frost, the weather signals one of the most wonderful periods in the garden as fall is the best time to plant trees.

The cool nights and short days mean they can concentrate on getting their roots established instead of using energy for top growth and/or flowering. When it comes to trees, it’s all about the right tree in the right place. Look at the plant tag to see how big and what kind of growing conditions are best for the variety. As host of the Talking Trees podcast, I’ve talked with arborists from all over the country and each one agrees that one of the biggest mistake homeowners make is not finding the correct site for what they’re planting.

Trust that plant tag for the height and width, there’s nothing sadder than a tree planted too close to a building that needs to be removed five years later. See if the variety prefers sun or shade and what type of moisture is right for the tree. Another tip I’ve learned from hosting is to choose a smaller tree, they get established much faster, something with about a two-inch-thick trunk, you’ll save some money too.

Here are some trees that come up with many arborists when asked about their favorites.

  • Black Tupelo for its fire engine red fall foliage.
  • Sugar Maple as a great shade tree and putting on a great fall show.
  • Stewartia as an off the beaten path choice. A beautifully shaped tree with good fall color, pretty peony like flowers in summer and stunning exfoliating bark.
  • One of my favorites is ‘Sugar Tip’ rose of Sharon. It’s sterile, so no seedlings, has green and white variegated foliage, and pretty double pink flowers.

Another common mistake is planting a tree too deep. There’s an area where the trunk meets the soil called the root flare. It must be above grade when planting. Even plants bought at a nursery as balled and burlap, or in containers, might have the root flare covered. Gently brush away the dirt at the bottom of the plant until the root flare becomes evident. Dig a hole two to three times as big as the root ball. To figure out an approximate depth, use a shovel handle to measure the distance from the bottom of the root ball to the root flare and transfer that to the hole. This is one case where we would prefer not to use compost as it can provide a planting hole. Experts say when the hole is filled with compost the roots won’t reach out past the compost. As long as there’s average garden soil in the planting hole, it can be used as the backfill when refilling the hole.

Mulch will help keep the soil evenly moist, but don’t make the mistake of volcano mulching. That will kill the tree eventually.

Mulch should look like a donut not a volcano and never touch the bottom of the tree.

Volcano mulching has become standard practice for many landscapers. When talking to arborists about why it’s become so popular, many think it’s because of the difficulty in removing any mulch dumped at the site for spreading.

The more homeowners who see volcano mulch and think it’s the right way to help their trees are actually doing the opposite.

When a tree is mulched the wrong way, bark can rot and feeder roots will emerge which won’t be able to get what they need when the mulch dries out.

A newly planted tree will need to be watered until the ground freezes solid if rain is scarce. The best time to water is in the morning, when possible. Soak the roots by letting a hose trickle at the base of the tree for a couple of hours, once or twice a week.

That will get the tree off on the right foot.

Planting a tree now is an investment in the landscape that will pay off for decades or longer.

Stewartia trees have a great shape, nice fall color, and pretty summer flowers.
For everyone who hates rose of Sharon, ‘Sugar Tip’ is sterile and beautiful.

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Doug Oster writes a column for The Green Voice Monthly Newsletter. He is also the host of The Organic Gardener Radio Show every Sunday morning at 7 a.m. on KDKA radio 1020AM.

To see more garden stories, photos and videos go to dougoster.com.