After lilacs finish flowering, prune off the old blossoms to increase the number of flowers next year. Do this soon because the plants will begin setting buds for next year's flowers. To reduce the height of the shrub, prune the old stems to the ground and allow new shoots to grow. Prune all at once, or gradually remove one-third of the old stems over a three-year period.
Knock Down Caterpillar Tents
It's another banner tent caterpillar year. We're in the middle of a population surge. Check apple, cherry, and other fruit trees for the white webbed tents, and poke them with a broom handle or long-handled pruners to break open the tent and expose the caterpillars to foraging birds. Or knock the tent to the ground and destroy the caterpillars. A spray of Bt will kill the exposed insects, too.
Steer Clear of Wet Soil
After all the rain we've had, the soil is saturated and compacted. Avoid stepping in garden beds and tilling or digging until the soil dries out a bit. But you'll want to attack those weeds that have been exploding with new growth. Use a long-handled weeder or a kneeling pad to reach them without stepping close to plants. Once the soil dries, cultivate the surface lightly to break any crust.
Examine your yard for areas with standing water, such as old tires or upturned garbage can lids, and dump them. Mosquitoes breed in these types of places, so by removing them you'll get a head start on controlling the pests. Use "mosquito dunks" in ponds. These disks contain a specific strain of Bt (Bacillus thuringiensis) that controls the mosquito larvae. Follow label instructions.
Attend to Tree Root Zones
Clear grass and weeds from root zone areas around tree trunks, and remove any suckers growing from the base of the trees. Spread compost, and top with a couple of inches of bark mulch. Keep the mulch an inch or two away from the trunks.