Celebrate spring by planting trees and shrubs

April 4, 2012
The crabapple should be pruned in early spring.

April is a time for big ideas.  On April 10, 1892, people planted a million trees to celebrate the first Arbor Day.  The word “arbor” means tree.  Odd word, “arbor,”  and odd concept of tree planting.  Trees last a long time, so it’s a bit of a commitment.

The first state to recognize Arbor Day wasn’t Nebraska, but California. Climate really determines when to plant trees, so America favors April, but in the Czech Republic, National Tree Planting Day is Oct. 20. Vietnam does not celebrate tree planting or Arbor Day. Van Mahotsav is the annual tree-planting festival in India, celebrated on June 5.

So Arbor Day never made it to become a national holiday, but it’s April and mild, so get out and a plant a tree.  Now, a common mistake when planting a tree is digging a hole that is too deep and too narrow. With a deep hole, the roots won’t have access to sufficient oxygen, slowing growth. A hole that is too narrow keeps roots from spreading out to feed and anchor the tree.

Transplant trees no deeper than the soil where they were originally grown. Make the width of the hole 3 times the diameter of the tree root ball or the spread of the roots.

If you are planting trees in clay soil, your digging can “glaze” the sides and bottom of the planting hole, making the hole smoothed over, and forming a water barrier.

If you notice that your planting hole is slick, use a garden fork to dig up the bottom and sides of the hole before planting your tree.

Leave a little mound in the middle of the bottom of the hole to rest the tree roots on.  Because it is just slightly higher than the surrounding area, water will flow away and not puddle and rot the roots.

Always use plain dirt to fill the planting hole.  If you use fertilizers and compost, you may actually harm the tree and prevent it from spreading its roots.

But spring tree care goes beyond planting; early spring is also time for pruning.  Because most spring-blooming shrubs and trees form blossoms on the previous year's growth, you should wait to prune until just after they bloom.

This poses a small dilemma because it is usually best to prune in their dormant season, just before new growth begins. Because the trees and shrubs are still bare, you can see the branch structure of the tree and prune to maintain the best form of the shrub or tree.

Pruning while plants are dormant gives the shrubs or trees a full growing season to recuperate and close the pruning wounds.  It also reduces the spread of diseases.

If you prune in the dormant season in late winter, many of your flower buds are lost.  For some trees, such as flowering crabapples, mountain ash, hawthorns and shrub cotoneasters, spring or summer pruning increases risks of infection and spread of fireblight, a bacterial disease.

To compromise, immediately prune early spring bloomers, like redbud, crabapple, dogwood and flowering pear.

By pruning as early as possible right after blooming, you still give the tree the entire growing season to heal the pruning wounds, and you still prevent pruning out next year’s flower buds. If you wait too long to prune spring-flowering trees and shrubs, the flower buds for next year may already have formed.   Prune at once after the flower petals fall off the tree.

As always, you can cut out dead and broken branches any time of the year.

Besides flowering trees the following shrubs can be severely pruned right after flowering: azalea (Rhododendron species), beautybush (Kolkwitzia amabilis), bridal wreath spirea (Spirea x vanhouttei), forsythia (forsythia x intermedia), hydrangea (Hydrangea macrophylla), lilac (Syringa vulgaris), mockorange (Philadelphus coronarius) and rhododendron (Rhododendron species).

Whether you plant trees or prune trees, or think of a new holiday, April is a time for big ideas.

  • Paul Barbano writes about gardening from his home in Rehoboth Beach. Contact him by writing to P. O. Box 213, Lewes, DE 19958.