Northern & Central Midwest
Stake tall perennials before the new growth reaches 6 inches high. Use perennial rings or simply insert pruned, shrubby branches in the ground near the plant crown. As the perennial grows, it will encompass the branches so they look a part of the plant, and the branches will hold up the perennial.
Harden Off Annual Flowers
Make sure annual flowers purchased from garden centers have been hardened off and adjusted to the vagaries of living outdoors before planting them out in the garden. Ask the garden center personnel if plants have been hardened off, and then still give the flowers some protection for a few days before planting.
Water Newly Planted Woodies
Make sure to give all newly planted trees and shrubs a long, slow watering once a week. They need to receive an inch of water a week and no more. If rains assist, hold off on your watering. It is possible to overwater and drown the newly developing roots. Don't fertilize until next year.
Monitor Hybrid Roses
Watch hybrid roses carefully from the day their foliage begins to emerge. Rose slugs, caterpillars, and black spot show up quickly and can decimate a plant in no time. Also, get in the habit of spraying roses off every day with a strong spray of water in the morning. This will get rid of most aphids.
Thin Vegetable Seedlings
As vegetable seedlings begin to emerge, make notes on a calendar to remind you to get out and thin the seedlings. It may seem a nuisance, but when thinned to the right spacing, vegetables grow strong and healthy. If left unthinned, they will not develop well because of competition for light, water, and nutrients.