Promptly plant perennials
after dividing them.

Dividing Perennials -- In the Upper South, you can still divide most perennials as long as they're not spring-bloomers and their foliage isn't any taller than several inches. Divide them if they are getting crowded (reduced blooms, a dead spot in the middle) or you simply want more plants.

Dividing Perennials

After the Thaw -- Plant warm-season annual flowers, herbs, and vegetables (tomatoes, peppers, basil, marigolds, petunias, and the like) as long as your region's last frost date has passed. (It's as late as May 30 at higher elevations and farther north.) If you're unsure, give your local garden center a quick call.

Frost Maps

• Those warm-season annuals include plants for containers, pots, windowboxes, and planters. Remove any cool-season flowers you may already have there. Work in a slow-release fertilizer. If there are plants overwintering in the container and you're keeping them, simply work the slow-release fertilizer into the top inch or so of soil.
• After the frost date, plant tender summer bulbs outdoors, including glads, cannas, and tuberous begonias.
• In the Upper South, you can still take advantage of April's cooler temperatures to plant seeds or established seedlings for cool-season crops such as radishes, peas, sweet peas, lettuces, and other greens. Plant seedlings of broccoli, cauliflower, and cabbages.

Frost Dates -- Plant seeds for corn, green beans, melons, squash, cucumbers, okra, sweet potatoes and other heat-lovers as long as the soil has warmed to at least 60 degrees F in your region. That's warm enough for you to walk on it comfortably barefoot and is usually two weeks after your region's last average frost date.

Your Region's Last Frost Date

Planting Trees and Shrubs -- Continue to plant container-grown trees, shrubs, perennial herbs, groundcovers, and perennial flowers.

Planting Trees and Shrubs

• When it comes time to mow your lawn, do so regularly and at the right height. It's the best thing you can do to control weeds and keep grass thick and healthy. Now, during cool weather, mow cool-season lawns such as bluegrass, ryegrasses, or fescues at 2 inches or so. Raise the mower blade to 3 inches once temperatures hit the 90s F. Mow warm-season grasses such as Bermuda, St. Augustine, and zoysia at approximately 2 inches all season long.
• April is a good time to aerate your lawn. Most lawns should be aerated every two or three years to alleviate compaction and reduce thatch. You'll need to rent a machine that takes out plugs of soil or have a lawn service do it. (As an alternative, fall is also a good time.)

Mulch Matters -- The soil has warmed up enough that you can apply a layer of mulch on flower beds and around trees and shrubs. It reduces weeds, conserves moisture, and prevents disease. Great stuff!

Mulch Matters

Deadheading 101 -- Deadhead rhododendrons and azaleas by cutting or pinching off spent flower trusses. This will neaten their appearance as well as encourage future blooms. Deadhead any other fading flowers as well.

Deadheading 101

• For mums, pinch off the last inch or so of the branches until July to assure bushy, well-flowering plants. While you're at it, cut back asters and other tall, floppy, late-summer bloomers by about one-third once they're a foot or so high. They'll be sturdier and flower better.

Pruning Shrubs -- You can prune your rhododendrons and azaleas after they're completely done blooming. After bloom time is finished is the time to prune other spring-blooming shrubs too.

Pruning Shrubs

Pruning -- Finish up any other pruning this month with the exception of evergreens, which can be pruned now through June or so.

Pruning

Composting 101 -- Your compost heap can probably use a little spring TLC. Open it up or tear it apart to get to the completely composted "black gold" down at the bottom and work it into the soil as you plant. Make sure remaining material is nicely chopped up or in manageable pieces (try running over softer stuff with a lawn mower equipped with a collection bag).

Composting 101

• After that frost date has passed, you can move your houseplants outdoors to a shady spot. It's a good time to repot and fertilize them to ready them for a summer growth spurt.
• For the lushest, thickest grass, give lawns another fertilization late this month or early next to help them prepare for summer's heat.

Stakes and Supports -- Stake tall plants that will need it now while they're just a foot or so high.

Stakes and Supports