January
Arborvitae - Pruning/Grooming - Ideally arborvitaes are planted in areas that will accommodate their natural size and shape. In this case they need no pruning except to remove damaged branches. Most often, however, arborvitaes threaten to outgrow their allotted space and they need routine pruning to control their size. Late this month or in February, do this by pinching off individual branch tips. Although they can be trimmed lightly at any time if necessary, it is best to prune them before new growth starts in the spring. Pinching off individual branch tips that extend beyond the general outline of the plant produces a softer, more natural look than if all the tips are sheared at once. If the arborvitae are intended to be a hedge they will accept shearing as well.
February
Arborvitae - Unfortunately, Arborvitae are among those plants that are very sensitive to the effects of salt spray or salt accumulation in the soil coming from the salt used by many communities to prevent ice on the streets. If you arborvitae is located close to a street which is exposed to salt then you might want to go to Yardener's Helper and type "salt damage" into the search window. That file will help you decide whether any precautions are necessary.
March
Arborvitae - These trees root easily and grow quickly. If you want some more specimens, plant 2 to 3 foot tall nursery stock in the spring or fall; but fall is best if you have a choice.
April
Arborvitae – This tree has both male and female flowers on the same plant. The male flowers are yellow and drop off in spring. These flowers release significant pollen which can be a hassle for folks with serious allergies. The greenish female flowers become the yellowish fruits that are held upright. These miniature cones turn brown and open up to release the seeds, then persist throughout much of the winter.
May
Arborvitae - The dense foliage and relatively small root-balls make newly planted Arborvitaes vulnerable to wind in exposed sites. To prevent their being blown over or uprooted before they become established, drive 3 sturdy supporting stakes into the soil equidistant about two feet beyond the Arborvitae’s foliage. Remove the staking after one year.
Because arborvitae have surface roots, it is a good idea to spread a 2 to 4 inch layer of chopped leaves, wood chips or other organic material on the soil to protect them. Keep the mulch about 6 inches from the stem of the shrub to avoid stem rot and possible rodent damage.
June
Arborvitae - Optional - This is the month when the bagworm can turn up on Arborvitae shrubs. The needles begin to look brown on the edges. Look for collection of needles glued together, about the size of a large strawberry. Hand pick the bags and throw them away. Learn more about Bagworms in Yardener’s Problem Solver.
In periods of drought, this tree should be watered just as much as other plants in the landscape. A soaker hose is the best tool, especially if it is a big tree.
July
Arborvitae – Early summer is a good time to do any minor shaping of this plant. To shape it, occasionally thin, shear, or pinch stem tips.
These trees do not need any watering unless there is drought conditions and there has been no rain for two weeks. Then you need to give the area under the drip line of the tree about an inch of water a week. Put a tuna fish can under the tree when you water to see when it is filled; that is an inch.
September
Arborvitae - Arborvitaes will benefit from an annual feeding for their first four or five years. Use a general-purpose, slow-acting granular fertilizer in the fall. Sprinkle one or two cupfuls, depending on the size of the Arborvitae, on the soil under the tree out to 1 1/2 feet beyond the tips of the branches (drip-line) for the rain to soak in. This task is optional for mature Arborvitae trees.
All evergreens drop some of their foliage every year, usually in the fall, but it can occur in the spring as well. Do not be concerned if you notice some brown, dead leaves on arborvitaes at the same time the deciduous trees and shrubs are displaying their fall colors.
October
Arborvitae – It is not wise to prune this tree in the fall or early winter. You will reduce the winter hardiness of the plant.
In northern areas spread 3 to 4 inch winter mulch on the soil over the root system to insulate the soil from extreme fluctuations in temperature that might disturb shrub roots. Keep it about 6 inches from the stem of the tree to avoid stem rot and possible rodent damage.
If there has been less than normal rainfall over the previous six months, it is very important to the health of a young evergreen tree to be deeply watered before the ground freezes for the winter. A soaker hose is the best tool for this job.
November
Arborvitae - For Arborvitae on sites exposed to the cold winter wind, consider rigging a protective barrier of burlap or garden fleece to shield them. Do not use plastic, as it does not allow essential air circulation.
Optional - Boughs or sprays of arborvitae foliage provide an attractive dark green element in flower arrangements. They are useful for Christmas holiday wreaths and as decorations in window boxes over the winter months. Arborvitaes that have been sheared closely for a hedge do not yield useful foliage for indoors.
December
Arborvitae – The dense foliage of arborvitae offer shelter to a wide variety of birds. Both birds and squirrels eat their small cones. Unfortunately it is also the favorite winter food for deer. So if you have a resident herd of deer, you may wish to take some protective precautions. For more information, go to www.yardener.com; key words "controlling deer".
