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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Still drought

Last year we experienced very low rainfall for almost the entire growing season; this year is only a little better. According to the various data sources I’ve looked at, our total rainfall in northern New Jersey is somewhere around 15 to 25 percent below normal, and the lowest rainfall totals occurred during the key spring months. And you can see the effects all around you. Notice all the evergreen trees with brown patches or dead limbs, the dead pine trees, the mature hardwood trees with dead limbs and dead crowns. Two, or even three years of drought are unlikely to affect a mature, healthy tree that’s growing in an appropriate site, but trees that are stressed are showing severe effects of drought. This includes newly planted trees that haven’t been watered properly, trees planted on the wrong site (for example, shade lovers placed in full sun, wetland species planted in dry soil), and trees approaching the end of their natural lifespan.

The Norway maples that were planted as street trees throughout much of this area around 50 or 60 years ago are particularly hard hit: many are diseased, and most are at the end of their lifespan. The two large Norway maples that we lost and replaced this spring are examples. Not that I’m sorry to lose these ugly and invasive trees, but the various towns’ Shade Tree Commissions and Departments of Public Works will have a great deal to do over the next few years. And it will take a while to regrow the street tree canopy we’re losing. Here in Glen Rock, we will be planting only native trees. Is your town doing the same?

You can’t do anything about the drought, but you can do something to protect your treasured plantings. Here are a few suggestions:

— Water new plants correctly at least for the first year; large trees can require supplemental watering even longer.

— If you have a tree with dead branches or, even more serious, a dead crown, consult an arborist and have it properly pruned or removed, especially if it’s endangering people or structures.

— When planting, always choose the correct plant for the site. This will minimize watering needs over the long term and help ensure the health of your garden.

 

Choosing plants

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Part of a sunny border at the end of June, including long-established and new plants, all very attractive to pollinators. From left to right: yellow sundrops (Oenothera fruticosa), purple beebalm (Monarda fistulosa), white dotted mint (Monarda punctata), orange butterflyweed (Asclepias tuberosa), more sundrops and butterflyweed, and white new jersey tea (Ceanothus americanus), plus grasses and taller perennials that will bloom later in the season.

I have a mental checklist that I use to choose plants for my garden. It goes like this:

1. Is it pretty? If I like the plant’s looks, I go on to:

2. Is it native to this area? There are many definitions of “native plant.” I mean, according to good authorities, was it growing here, in northern New Jersey, before European settlement? If it most likely was, the next question is:

3. Is it a pure species? I greatly prefer species to hybrids or cultivars or varieties. Species are fertile, and I want to be able to collect seeds. Species were designed by nature, not by plant growers or scientists, so they are likely to produce flowers in colors that pollinators can recognize and that are not so big the stems can’t support them. If I can find a pure species, the next question is:

4. Is it adapted to the specific site? No matter how pretty or how native, there’s no point in planting something that can’t survive in the specific soil, water, and light conditions; there’s no point in planting a large tree in a small bed or groundcover where you need a shrub or a wetland plant in dry soil. If it is adapted to the site, I ask:

5. It is useful to wildlife? I plant for the birds and the butterflies and the myriad pollinators too small to notice or to name. I check reference books and field guides to find out what the critters want to eat. Chokecherry yes, redbud no. Space is limited, and one is useful to a wider variety of species than the other. If it’s a good wildlife plant, I ask:

6. Is it common in the area? There are few plants more useful to a wider range of animal species than oaks, but there are already lots of oaks (there are also lots of redbuds, because people plant them as front-lawn specimens). So I’ll plant something else, equally useful, that used to be common but is now missing–like serviceberry and elderberry. Once I decide on that rarer plant, I need to ask:

7. Can I find a commercial source? This is usually the problem. I choose plants for clients for a living, so I’ve developed a fairly wide range of sources, but I often wind up substituting a different species after a fruitless search. Sometimes the plant I want finally appears on the market, sometimes it never does. I would like a local source but will settle for a midwestern one. If I can find a source, the final question is:

8. How was the plant grown? I want healthy plants, and I particularly want plants that were grown in a nursery, not collected from the wild. I would prefer to inspect the plants myself, but I’ll settle for mail order from a reputable grower if absolutely necessary.

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Chokeberries (Aronia melanocarpa) at the end of July. The birds devour them the second they are fully ripe.