Shade Trees

Air Date: October 31, 1997

CURWOOD: This is Living on Earth. I'm Steve Curwood. And right now I'm standing under a beautiful large ash tree in the back yard of Michael Weishan. He's editor in chief of Traditional Gardening as well as Living on Earth's gardening expert. Hi, Michael.

WEISHAN: Hello there, Steve.

CURWOOD: This is a magnificent tree. I mean, how old is this, would you say?

WEISHAN: My guess is that it's probably better than 100 years old. From its girth, maybe 100, 125 years old.

CURWOOD: So 100, 150 years ago, someone decided to plant these trees here. Is it important to plant these large trees today?

WEISHAN: Well, it's very important, for a number of reasons. Take this tree, for instance. The size of this tree is such that it allows the whole back of the house to be shaded in the middle of summer, and it has a terrific cooling effect. It provides this pleasant place on a hot, sunny day to sit under, and shades the terrace, and on a day like today provides shelter from the raindrops falling.

CURWOOD: These trees offer, you know, the mechanical services of shade and the visual pleasure, but do they do something else for us humans as well?

WEISHAN: They've done studies that have shown that there's some connection between the amount of urban violence and the fact that areas have no trees. I think on a purely psychological level, trees, large trees just make us happy.

CURWOOD: So what are the best trees to plant for the long-term, then?

WEISHAN: Well, there's a large number of trees, actually, one can plant. Zelcovia, for instance, which is a great tree. It's a replacement for the American elm tree, has a similar sort of vase shape, which is very pretty, grows to 60 or 70 feet. Trees like beech, lindens, magnolias, oaks. All these trees form very large, wonderful shapes in the garden and are really quite an advantage to the landscape. And very valuable, too, by the way.

CURWOOD: Really?

WEISHAN: Well, from a home appraiser's perspective, large shade trees add between $10,000 and $20,000 to the value of your house. Which is one of the reasons I'm unhappy of its current state of health.

CURWOOD: Is this tree on the way out?

WEISHAN: I'm afraid this tree is on its way out. It's suffering from what's called ash tree decline, and they tell me 10 years is the most that this tree will continue onwards.

CURWOOD: Otherwise, this ash tree would be good for what? Two hundred years?

WEISHAN: Probably not that long, but certainly another hundred.

CURWOOD: Now, I'm wondering, these trees planted some 200 years ago or 100 years ago were planted under totally different conditions. I'm thinking of pollution. If we plant a tree like this today, does it have the same kind of chance that its grandfather had a century ago?

WEISHAN: Well, it is an act of faith. But then, tree planting or gardening in general has always been an act of faith. Yes, it is true that there were considerably fewer stresses on trees. But what really has contributed to the decline of trees in this country is the sort of globalization of pest transport. In the South, for instance, the Formosan termites have been imported, which are chewing up the live oaks in Louisiana at a terrific rate, and there's no cure. Dutch Elm Disease was another example of that; so was gypsy moth.

CURWOOD: Is it hard to plant a tree?

WEISHAN: No, actually, we're going to do a little demonstration today to show you how easy it is.

CURWOOD: Okay, let's go.

WEISHAN: Okay.

(Footfalls on gravel)

WEISHAN: All right. Of course, we're in rocky New England here, so you know, you hear the rocks. But it's not particularly difficult. Essentially, what we're doing is just digging a hole that is about twice the size of the pot.

(Digging sounds)

WEISHAN: You want to lend a hand here, Steve?

CURWOOD: Sure. Let me try this here.

(Digging continues)

CURWOOD: I have to say, I don't recognize this tree.

WEISHAN: No, I bet you won't, because it's fairly rare, actually. And it's a good example of some of the more interesting trees that are fairly resistant to problems that you can plant these days. This is Davidia Enruvolia Crada. It was brought back by Ernest Wilson in 1904 from western China. It blooms in June with large, 7-inch-long white blossoms, which are very similar to wisteria blossoms. So it's quite a spectacular tree, and it'll grow 40 or 50 feet high and about as wide. I've only seen it once, at the Arnold Arboretum in Boston, where they have a specimen, and actually where this tree comes from, it's actually a seedling of that very tree that Ernest Wilson brought back to the United States.

(Digging continues)

CURWOOD: What do you think? Is this deep enough?

WEISHAN: Yeah, I think that's about right. Let me just take the shovel from you for a minute. I'm going to just scoop out some of this loose soil. Now, I've already added some super phosphate to this soil this morning. Super phosphate helps the root grow. If we were planting this in the spring we would have added some type of either organic fertilizer like well-rotted manure or compost, or a simple garden fertilizer like 10-10-10 very lightly. Very lightly. But at this season at the year, just super phosphate.

CURWOOD: Okay.

WEISHAN: So that's already in. Now we're just going to --

CURWOOD: Tip this thing a little bit?

WEISHAN: Yeah, just tip it over, now let's see if it's going to come out of its pot there. Easily.

CURWOOD: [Voice straining] Down she goes!

WEISHAN: Down she goes oh, Steve, you're an expert digger.

CURWOOD: That's it there.

WEISHAN: Yeah. Perfectly, perfectly done. And I say perfectly, because the level of the tree was that originally in the pot, and the current soil level are exactly the same. And you want to be real careful not to bury the tree any deeper than it was in the pot, because that's a sure way to kill a good tree.

CURWOOD: Uh huh. Okay.

WEISHAN: So now all we do is, I'm just going to fill in here.

(Shovel scraping sounds)

WEISHAN: I'm going to get the hose out and water this down very carefully, because what you want to do is settle the soil around the root ball so there's no air pockets. That's the other most important thing. And that's it. It's planted. It's our gift for the future.

CURWOOD: Well, Michael, thanks for letting us get our hands dirty in your garden.

WEISHAN: Well, it's been a real pleasure. Any time I can get free labor I'm very happy.

CURWOOD: (Laughs) Michael Weishan is editor in chief for Traditional Gardening. And if you have any questions for him, you can reach him via the Living on Earth web site. Go to www.loe.org. That's www.loe.org.