Early May is crunch time in the garden. Plant trees and shrubs, watch for freeze damage, sow cool-season veggies, mow the lawn and shop for plants and supplies.
FREEZE DAMAGE
• Certain shrubs were damaged by last November’s freeze, including euonymus, privet, cotoneaster, juniper, spirea, boxwood, weigela and hibiscus. If you’re uncertain whether the plant is dead, wait a few more weeks for signs of life — you might be lucky.
• If it’s still alive with little damage, just remove the dead branches. If more than half of the plant is gone, then it’s time to get the shovel and think about its replacement. Just don’t be hasty. Give the plant plenty of time to leaf out.
• You can check for live branches anytime by using your fingernail to lightly scratch a branch. Green and flexible? It’s alive. Brown, dry and brittle branches without swollen or emerging buds are dead.
• Dead tips on evergreens such as boxwood and yews can be pruned off with bypass pruners.
• Junipers and arborvitae Cut individual branches back to a side shoot to hide the pruning cut. See photos at www.ext.colostate.edu/mg/gardennotes/ 617.html#juniper
• Dead branches on deciduous shrubs can be pruned out now or anytime through the growing season. Use loppers for larger branches. Cut the dead branch to the ground or back into the shrub. Only remove up to a third of the oldest branches per year.
• is always recommended after flowering, whether or not it received freeze damage. More: www.ext.colostate.edu/mg/gardennotes/616.html
GARDENS AND LAWNS
• Clean up any remaining annual vegetables or ornamentals from last year. If they had diseases, don’t compost them.
• Continue direct seeding cool-season seeds outside. Quick-maturing crops like radishes, lettuce, spinach, mustard greens and arugula can go in beds or pots. Also seed kale, Swiss chard, onions and potatoes. Plant indoor-started cauliflower, cabbage, broccoli, and Brussels sprouts.
• Sow warm-season seeds indoors for transplant at May’s end: squash, melons, cucumbers and pumpkins. These transplants are also easy to find at garden centers, where you’ll also find baby tomatoes and peppers. All of them need to wait to be planted out until it’s warmer.
• Hand dig or spot-treat perennial weeds.
• Get your sprinkler systems turned on. Water the lawn weekly if weather is warm, dry, or windy. But when we get rain like most areas did last weekend, reset your sprinklers to “manual.” Mow lawns at 2½ to 3 inches.
TREES
The purchase of a tree can require as much, if not more, study than buying a car. You’ll probably have a tree longer than a car — and Consider the following when shopping.
• What do you want or need from this new tree? Deciduous or evergreen (or both)? How tall can the space handle? What’s important to you in a tree — bloom, leaf color, fruit or berries, fall color, interesting bark? More: www.ext.colostate.edu/ptlk/1120.html
• Look around your neighborhood. If there are a lot of a certain species, it’s actually best to not plant more of that tree. Diversity in the urban forest is important so that disease and insects don’t run rampant.
• Talk to tree-industry professionals or experts at local garden centers and tree farms. Check online resources that specialize in plants for the intermountain West. And check with your municipalities’ forestry office for suggestions. Denver has a helpful street tree list at
• Tags on trees at nurseries lists the tree’s height at 10 years; you should expect the tree to grow larger.
TREE PLANTING
• Get utility lines marked before you dig: 811 is the number to call. You can also go to uncc2.org
• Keep the tree moist and in a shady, protected spot before planting. Handle the root ball gently.
• Don’t plant the tree too deep. Trees planted too deeply will decline, often slowly, and many die.
• Dig a wide, shallow, bowl-shaped hole. The hole should be three times as wide as the root ball. The planting hole depth should be only as deep as the root-ball height. And hold onto that backfill soil: You’ll use that to fill in the hole after planting.
• Place the root ball on undisturbed, firm soil (not fluffed up soil, because it will just sink down again). Remove as much of the burlap or plastic wrapping, ropes and wire as possible. If the burlap is all that’s keeping the root ball together, then make several slits and peel it back to the ground. Remove as much wire as possible.
• Make absolutely certain the top of the root ball rises 1 to 2 inches above soil grade. This can be tricky; sometimes soil disguises itself as the actual root ball’s top. Look for at least two structural roots within the top 3 inches of the root ball. In some cases, the upper structural roots may be deeper in the root ball, so remove the soil until they are found. Do not cover the top of the root ball with soil. Worried that your planting hole is too deep? Get a yardstick out and lay it across the hole to check. I know; this part is tough to visualize. You can see at www.ext.colostate.edu/mg/gardennotes/633.pdf
•Amend the backfill soil only if it is extremely clayey or sandy. Even then, amend by only 5 percent and mix well. A correctly dug planting hole — wide enough and the proper depth — is the crucial element.
•When you’ve placed the tree and filled in three-quarters of the planting hole, slowly add water. Once it has soaked in, finish filling the hole, making sure the top of the soil slopes away from the trunk.
• Staking is generally not needed unless the site is windy or the new tree might get disturbed by passersby. Use flat, grommeted straps, never wire, rope or hose pieces, to anchor a tree to three stakes.
• Mulch with wood chips to a depth of 2 to 4 inches. But keep mulch away from the trunk. The mulch ring should be three times the size of the root ball; increase its size as the tree grows. And don’t roll sod right up to the tree; turf competes with tree roots. In time, the tree usually wins and turf suffers.
• Recently planted trees and shrubs will need frequent, light watering; the root ball can dry out in just a few days. More: www.ext.colostate.edu/mg/Gardennotes/635.html.
• There’s no need to fertilize trees at planting time.
Betty Cahill: gardenpunchlist@blogspot.com
Punch List by Betty Cahill, Special to The Denver Post
