Your First Garden: What You Need to Know Before You Plant a Tree or Shrub

We have a beautiful dogwood in our front yard. Like the other few plants on our property that are actually thriving, this tree was here long before we arrived—and long before I started gardening (or what I like to call, killing plants with my good intentions). Trouble is, an arborist recently told me that our dogwood, which grows sweet white flowers in the spring and turns a gorgeous orangey maroon in the fall, doesn’t have many years left. He suggested I start growing a new tree near the dying dogwood so that when it finally putters out, there will already be a new one taking root to replace it.

Aside from the fact that the strategy seems very Machiavellian, with overtones of Sunset Boulevard, the idea of planting a tree is daunting. I have problems growing flowers; how on earth can I succeed at growing a tree?

I consulted with Rowan Blaik, director of living collections at the Brooklyn Botanic Garden, for some advice. Here’s what I learned.

N.B.: Featured image via Solitair Nursery, from Shopper’s Diary: Specimen Trees and Special Shrubs from Solitair Nursery in Belgium.

Q: When is the best time to plant a tree or shrub?

A: Blaik says the better question to ask is, When is the worst time to plant them? “There are times of the year that are really bad for planting a new tree or shrub. In the winter, the ground is frozen; in the height of summer, you have to water loads to keep the soil moist enough.” Basically, the weather conditions in those seasons put too much stress on new plants. If the tree is an evergreen, fall and spring (when temperatures and conditions tend to be mild) are optimal. If it’s a deciduous specimen, fall is best; planting deciduous trees in the fall, when they start to slow down anyway, offers a gentler entry for new transplants.

Q: Why are some trees and shrubs so much more expensive than others?

A: There’s a premium on unusual plants, so the rarer a specimen, the more expensive it tends to be. There’s also often a difference in price because of size. Larger trees or shrubs tend to be more expensive, since the buyer doesn’t have to wait as long for them to mature. And last, prices go up for field-grown trees, says Blaik, as opposed to container-grown specimens. Field-grown specimens are usually found balled and burlapped at nurseries; this means the root ball has been dug up and wrapped in burlap. Container-grown specimens, planted and grown in pots, tend to be smaller. You’ll find many of the latter type at mass-market retailers like Home Depot and Lowe’s. Trees are sometimes also available at nurseries in a third form, bare root, but Blaik doesn’t recommend that option for beginners.

Q: How do you know if a tree or shrub is healthy before you buy it?

A: How many times have you seen a wilted plant in a store and wondered when its last watering was? Clearly, not all plants in stores get the treatment they need. Here are some warning signs to look out for, according to Blaik. Are there roots growing out of the pot? Are there weeds on top? Is it lopsided? Are there dead leaves or branches on it? Is there a gap between the root ball and the sides of the container (a sign of under-watering)? If the answer is yes for one or more of these questions, move on and look for a healthier plant. Blaik also recommends asking an employee at the nursery to take the pot off so that you can examine the roots; if they are growing in a spiral, a sign that the pot is too small for the the plant, look for another one.

Q: What are best practices when it comes to planting a tree or shrub?

A: First, prepare the area where you plan to dig the hole for the tree or shrub before you bring it home. Find the spot and clear it of debris and weeds. When you bring the root ball home, submerge the entire thing (container and all) in water for 10 to 30 minutes to ensure it’s well-watered before you plant it, says Blaik. Dig the hole to a depth no deeper than the rootball (so that the top of rootball is even with the ground); the width should be about three to four times wider than the root ball or container. If the ground is really compacted, he recommends tilling the sides and the bottom of the hole—but not too much, he cautions: “If you make it too soft and fluffy, you will think the root ball is planted at the right depth, but it will eventually sink.”

Q: How much water does a young tree or shrub need?

A: “It’s vital that you water newly established plants,” says Blaik, but it has to be the right kind of watering. “Shallow watering will give you shallow roots. Deep watering every now and then is better than lots of superficial watering.” Mold the soil around the base into a little basin so that the water soaks in where it’s needed (and doesn’t dribble off elsewhere). And don’t just turn on the hose and disappear. He recommends hand-watering and paying attention to the soil as you do it. “Water, pause, watch the water disappear, then repeat until the time it takes for the water to soak in gets slower and slower. When the ground is well-saturated, the water will take a while to disappear into the soil.” A fail-proof way to ensure your new tree gets watered well: wrapping the base with a tree gator. Blaik is a big fan of these zippered bags for the summer months. One bag holds up to 15 gallons of water that will gradually seep into the soil around your tree over the course of five to nine hours, thereby ensuring a deep water saturation.

For more beginner gardening stories, see:

• Your First Garden: What You Need to Do in Fall for a Lush Lawn in Spring
• Your First Garden: What You Need to Know Before You Plant Bulbs
• Your First Garden: What You Need to Know About Raking Leaves
• Your First Garden: What You Need to Know About Topsoil