JUNE HORTICULTURAL HINTS
Peonies, rhodies and other spring bloomers. Once the blooms have died, it’s time to prune spring blooming shrubs such as rhododendron, spirea and lilac; and trees such as magnolia and dogwood for size or shape. Doing it now means you will not risk removing next year’s flowers. Even if you do not need to prune, remove all dead flower heads to eliminate a site for diseases and to conserve plant energy which would go producing unwanted seeds.
Mulch. It’s finally warm enough to add fresh mulch around trees and shrubs. Your layer should be no more than two inches deep, and never touch the bark of the plant’s trunk. Instead, pull the mulch at least an inch away from the bark of any plant.
In the vegetable garden. The soil and air are warm—plant tomatoes, peppers, eggplant, squash, melons and other summer crops now. After you’ve finished planting the summer crops, remember a mulch of heat-treated straw around them will reduce diseases caused by infected soil splashing up on leave as well as preserve moisture around the roots. It will last all season, can’t add weeds (heat treating kills weed seeds) and improves the soil as it breaks down next winter.
Early blight is the most common source of disease in growing tomatoes. Endemic in our soil, early blight can cause damping-off, collar rot, stem cankers, leaf yellowing and fruit rot. Two inches of a clean, organic mulch will reduce your soil-borne diseases as well as keeping weeds down and the soil cooler and moister on hot days.
Pinch back the tops of annual herbs to promote bushier growth. Herb flavors are strongest early in the day, so do your harvest then and refrigerate until you are ready to use them.
Leave your grass longer. Move your mower blade to its highest setting; preferably three inches - a height where the grass will shade out most new weeds. The longer grass keeps roots cooler during hot days when it is more susceptible to disease and insect damage in the summer. If your lawn is cut by a service, specifically ask them to raise the blades on their machines to that height when mowing your lawn.
Let your lawn rest. Stop any lawn treatments until the end of summer. Fertilizer promotes vigorous top-growth at a time when the rainfall will be decreasing, and when the increasing heat is telling the grass to slow down. Herbicides (weed-and-feed, broad-leaf herbicides) will damage grass roots in the heat of summer. Pesticides are indiscriminate killers, killing off beneficial insects along with pests. Unless you identify a specific pest. there are far more ‘good guys’ out there that keep the lawn and garden going by eating the bad guys.
It’s swallowwort season. A mild winter and early spring have given black swallowwort an ominous head start. It looks like a vine as it grows, then a pretty purple flower appears (in June this year) and finally a pod full of seeds (July and August). While the pods look somewhat like those on milkweed, they will kill monarch butterfly larva that hatch from eggs laid on these plants. Pull the entire plant (it will come out easily) by hand before the flowers ripen into pods. Keep an eye on the area because swallowwort may re-appear. Do not compost or throw any swallowwort into other areas. It will aggressively cover everything in your garden. Bag and add to your trash any swallowwort you find on your own property, then encourage your neighbors to do the same.