Sun vs. shade

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Blossoms on a dogwood tree (Cornus florida) growing in full sun because of the death of a large canopy tree that used to shade it.

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A tree of the same species, on the same day. This tree is still shaded by another tall canopy tree.

Flowering dogwood is a very beautiful native tree that’s often used as a specimen, typically planted out on a front lawn in full sun. But this is never how the tree grows in nature, where it is always found growing under various species of oak trees. The only time dogwoods want full sun is in early spring, before those oaks leaf out.

The two dogwoods shown above are both growing on our front lawn. When I planted them, both were in shade, but since we lost two large trees last spring due to drought and decrepitude, the first one is now in full sun. The small oak we planted to shade it won’t be big enough to serve that function for several years. The tree in sun now blooms and leafs out considerably earlier than its relative only thirty feet away. It will experience a great deal more stress from heat and drought and will probably need supplemental watering. It is more likely to show the effects of anthracnose or other diseases. A native tree that’s adapted to a sunny site, such as a serviceberry, would do better in this spot.

Trees react to their environment in many ways. Pay attention to the total environment when you plant!

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An oak and two ashes

Or is that two ash? To replace the Norway maple we lost in the windstorm last month, and the other big one that didn’t leaf out this year, we planted a swamp white oak (Quercus bicolor) and two green ash trees (Fraxinus pennsylvanica). Because my goal in choosing plants is always to restore the natural environment, I wanted a silver maple (Acer saccharinum), the species that belongs in this sandy floodplain soil. But that species doesn’t seem to be available commercially. My second choice, an American elm (Ulmus americana), was available locally only in small sizes. My third, hackberry (Celtis occidentalis), wasn’t available at all. So I settled for the swamp white oak, a lovely native species that will achieve the right shape and size, and is fast growing, but is not ideal for my coarse, sandy soil. Often when you insist on planting natives, you have to compromise.

We left the snags (dead tree trunks) in place, as you can see in the pictures. Snags are terrific for birds and other wildlife, because lots of insects will live inside them as the wood gradually decomposes. Right now, the snags kind of overpower the trees, but that will change over time.

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This 2 1/2″ caliper swamp white oak was planted on our front lawn today. If it does well, it will reach maturity in 150 years.

The big Norway maple in back had one good quality: it cast afternoon shade over our patio. No shade until after 5:00 this year, or maybe next as well. But the two green ash we planted are very fast growing. These trees are one of the two or three best choices for this particular site. I was looking for white ash (F. americana), green ash, or hackberry.

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This snag is 12′ tall (maybe just a tad too high). And the two young ash are each a bit crooked but should straighten out quickly.

Here’s a closer look at the base of the trees after planting. Notice that we left a donut-shaped ring of soil around each tree. You could use mulch as well, but it’s most important not to mound anything against the trunk of a tree. That’s a really good way to encourage fungus infections. The tree should be planted at the same level as it was before it was dug up, or perhaps slightly higher. Never lower. The tree’s most important and fragile roots are the ones at the soil surface. You never want to smother them with extra soil or mulch.

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This tree was planted slightly too high (note the demarcation line between trunk and root), but that’s OK. Never plant a tree or shrub lower than it was before.

After planting, I thoroughly watered each tree in by running an oscillating sprinkler for about 1 1/2 hours (supplying 1 1/2″ of water). Thorough watering is the single most important thing you can do to help a tree (or any plant) establish its roots in a new location. Watering eliminates air pockets in the soil and helps the roots make firm contact with the new environment.

These trees were my Mother’s Day present, and I love them!