Pot Up Your Containers
Though nights are still chilly, the days are warm enough to fill your windowboxes, large pots, and hay racks with most annuals -- coleus, sweet potato vines, optic grass, snapdragons, Persian shield, salvia, nasturtiums, elephant ears, and geraniums. Annual vinca, a.k.a. periwinkle, thrives in summer heat so wait to plant those sun- AND part-shade tolerant beauties till temps hover at 70 degrees or more. Impatiens, too, will do better planted in warmer weather -- at least two weeks after last frost.
Cover Up Veggie and Flower Seedlings
Floating row covers allow sunlight, water, and air to reach tender seedlings as well as larger veggies and annual flowers. This light, polyester fiber fabric protects seedlings and young plants from chill and wind. It also is a toxic-free barrier to insects! Row covers easily "float" over plants for weather protection. To keep insects at bay, they are best propped over bamboo or metal hoops and secured at the sides with metal staples.
Divide Ornamental Grasses and Autumn-Blooming Perennials
Before ornamental grasses fill out and perennial sunflowers take over half the garden, feel free to divide the clumps ... and share the bounty. Aster, monarda, and stachys are easily divided by pulling clumps apart by hand or with a sharp spade or knife. Dense clumps of ornamental grasses, perennial sunflowers, hostas, daylilies, shasta daisies, and border phlox are best lifted from the ground, then separated into manageable sections with spade and spading fork.
Pinch and Prune to Control Floppy Perennials
Peeved at overgrown perovskia (Russian sage)? Tired of leggy border phlox? Pinching and pruning select perennials now will encourage extended flowering and more compact plants. Cut back or pinch perovskia and monarda by half (clip 12-inch stems to 6 inches) for fuller, shorter plants. For longer flowering and shorter, denser stands of Phlox paniculata, cut back a third of the plants in mid-May and a different third in early June. This will stagger flowering times.
Wait for Green Before Pruning Lavender
Be patient with your lavender. Give it time to wake up to spring. Woody growth is slow to break on these subshrubs. Wait for new, green leaves to sprout on woody stems before getting out the pruners. Even then, cut off only the dead tips! Green stems are alive; dead stems are brown or tan inside.