March is one of the loveliest and most productive months in the Zone 7 garden. You can plant cool season veggies this month, but wait until April before putting out tomatoes and planting beans.
Our local 4H agent is selling blueberries and strawberry plants as a fundraiser. Both are excellent choices for edible landscapes, plus 4H and other youth gardening and farming opportunities are well worth supporting. Check around for similar programs where you live. Happy gardening!
Planting Preparation. It's time to plant cool spring vegetables, including broccoli, lettuce, spinach, greens, cabbage, chard and root crops, and cool season flowers like snaps and calendulas. You can still plant onion sets, peas and potatoes.
Seed Starting. It's time to start tomatoes, peppers and eggplants indoors, along with flowers like zinnias and cosmos. Wait to set out or plant warm season crops until next month (April 15 in our area).
Woody Plants. Before woody plants break dormancy and as they begin to bud out, take care of pruning chores and applications of preventatives such as dormant oil.
Preparing Beds. Prepare your garden beds deeply and well, especially for vegetables. However, don't try to work the soil—with spade, fork or tiller—until the soil is dry enough to crumble in your hand. Especially with our clay soils, be careful not to work them when wet. (Remember this is for vegetables only—most of the garden does not need regular tilling.).
Direct Seeding. Direct seed mustard, lettuce, spinach, radishes, turnips, beets, carrots (don't delay), onion sets, chard, mâche, mesclun, and Asian vegetables (try gai lan, 'Chinese flowering broccoli', it's great and easy.). Anything that prefers cool weather and grows fairly fast.
Keep an Eye on Floating Row Covers. You may want to pull them back on unseasonably warm days, but don't remove them from the garden. Next thing you know it we'll have a freeze and you'll need them again.
Keep Pruning. Continue pruning fruit trees, landscape trees and shrubs. Remove dead or broken branches, crossing branches that rub another branch, and all dead and diseased wood. Also trim flowering shrubs like Forsythia and Japanese Camellia after they bloom.
Apple Health. Check with your extension agent to see when and if you need to treat your apple and pear blossoms with organically-approved agricultural streptomycin if fireblight is present in your area. Pears are extremely susceptible.
Flower Starting. Start warm season flowers like zinnias, marigolds and cosmos, along with any flowers you can't find in your local nurseries. Start perennial flowers now, too, like hollyhocks, Monarda, and many others. Set out any cool season flowers, like phlox, calendulas and snaps, that you started next month.
Don't Forget to Deadhead. Deadhead daffodils when blooms droop, but leave the leaves alone. Daffies need their leaves to recharge the bulbs for next year. Cut them back in a few weeks, after they turn brown. Deadhead those pansies, they will bloom longer and look better if you do. They also appreciate a feeding with fish emulsion or another organic fertilizer this month.
Start Mowing Fescue Again. Tall fescue needs to be at least 3 inches in height to outcompete the weeds. Mow at least once a week, never removing more that 1/3 of the leaf. The easiest way to handle the clippings is by grasscycling (i.e. leaving clippings on the lawn). Sometimes, the lawn generates so many clippings in the spring that I'll rake up a load and mix them into my compost.
Happy Houseplants. Repot any houseplants that need it in a good potting mix. Don't use an overly big pot, just graduate your pot up a step. If you've been rooting cuttings of Creeping Charlie, begonias, or other houseplants, plant them into pots when you see roots have forms.