April - Is This Spring or Summer? by Lee Vanderpool
Although the spring equinox has just passed, summer appears to be upon us. Temperatures went from the daytime 50’s and nighttime 40’s to daytime 80’s and nighttime 60’s. The poor bonsai trees on your benches must be confused about what they should do - grow or go into summer dormancy! You should have completed most of your repotting - if you really need to repot boxwoods or very late flowering trees and shrubs this may still be done if roots are treated carefully and not disturbed too much. Azaleas should be repotted immediately after flowering. All plants should be kept from direct sun for several days after repotting to give the roots a chance to re-cover and to begin to regrow. Still too early to repot tropicals, leave them until late May or June.
Watering frequency should be stepped up to at least once a day and fertilization should begin now. Spray with extra fine oil to control scale and sucking insects. Applications of oil should be made two times about two weeks apart. Be sure you spray the undersides of leaves since that is where many scale insects reside. If aphids become a problem on new foliage, spraying with a strong jet of water will usually dislodge them. Once they have been knocked to the ground, they will not return to the plant. Perform this procedure every two weeks throughout the summer.
Collecting plants is about over for this year. If you have not dug red maples, sweet gum or other deciduous saplings for that forest planting you intend to do this year, it is probably too late unless you can find some small trees which have been shaded by a larger one and they have not leafed out as quickly. If there are a lot of small trees, dig a few and experiment. You might be pleasantly surprised that they all survive and grow enough that you can do that forest this summer, after all.