March Gardening Tips

Outdoor Yard and Garden Tips

  • Many types of annual flower plants can be started indoors this month. Most are started 5-6 weeks before they are planted outdoors. Begonias, sweet peas, geraniums, and impatiens need to be started 10-12 weeks before the last expected frost. Sunflowers and zinnias can be directly seeded outdoors after the danger of frost has passed. This is also a good time to start pepper, eggplant, and basil indoors. 
  • Pansies are now widely available at nurseries and garden centers and can be planted for an early display of color in garden beds. However, it’s a cool weather plant that declines quickly when it starts getting hot.
  • Cut down perennials and over-wintering ornamental grasses to within 2 inches of the ground and remove plant debris from flower beds.  Divide perennials, and top-dress beds with 1 inch of compost. Pull weeds and apply a two-inch layer of mulch to prevent weed seeds from germinating. 
  • Leaf scorch symptoms can occur on broadleaved evergreens. Damage is most severe on shallow-rooted plants such as azalea, rhododendron, holly, cherry laurel, boxwood, or those at their northern limit for winter hardiness (Magnolia grandiflora, Aucuba japonica, Camellia spp. and others). In many cases, damage occurs during the winter months but symptoms appear in the spring as the plant begins to emerge from the winter dormant period and move into the spring growth phase.
  • Prune roses starting in mid-March to maintain their shape and size. Roses typically experience some winter kill. To determine whether or not a branch is alive, simply scrape the bark with a sharp knife and look for green tissue. If it is brown prune off the cane. Early spring pruning of roses:
  • If you have ash trees that need to be protected from emerald ash borer consult a certified arborist for management options. 
  • March is the beginning of the planting and transplanting season for trees and shrubs. But, avoid working or walking on wet soil; wait until the soil dries out. How do you know when your soil can be turned or tilled? A simple test is to form a clump of your soil into a ball. Bounce it up and down in your hand a few times. If it breaks apart easily it’s probably OK to dig!
  • Late winter-early spring is considered the second-best time to seed your lawn make repairs, or to cover bare areas. The best time is late August through mid-October. Seeding should be completed by late April. 
  • Improve soil quality by mixing 1-inch of compost into your vegetable beds as soon as the soil is workable and not too wet.
  • Cut back last year’s perennial herb plants. They will look better and have room for new growth.  It will also help reduce insect and disease problems.
  • Termite swarmers can become active on warm, sunny days. If you have a swarm, it may mean that there is a colony living under or very near to your home’s foundation. The problem should be investigated, especially if swarmers are found indoors.

Vegetable Garden Tips

  • As soon as soil can be worked, plant potatoes, peas, onion sets, leeks and other cool weather crops, including beets, Chinese cabbage, kale mustard and turnips.
  • Amend soil according to soil test results, which may call for adding lime or other nutrients. When the ground can be worked, dig in that layer of well-aged manure, compost, mushroom soil, or leaf mold to improve soil texture and fertility.
  • Put up trellises and teepees for peas, pole beans and other climbers. Waiting until plants come up can harm plant roots.
  • Harden off leeks, shallots, and onions in cold frame, or set outside on a porch or protected area, a few hours a day at first, before bringing them in at dusk; then gradually working up to eight hours a day. Do this for about a week, before transplanting in the garden. (Follow this same procedure for any crop started indoors.)
  • Apply water around the base of seedlings when planting that contains a soluble fertilizer. This will help roots grow strong.
  • Sow more seeds of spinach, lettuce, arugula and other salad greens in cold frames or in the vegetable bed, under row covers. (Floating row covers are made of spun-bonded polyester. They let in air, light and water, offer some protection from frost, and exclude insects and bigger critters.)
  • Start seeds of eggplant, pepper (if not started in February) broccoli and cabbage indoors under lights, to be ready for planting outdoors in six to eight weeks.
  • Keep a garden planner or journal. Note each activity, with date, in your garden notebook. Jot down weather, temperature, when seeds germinate, plants flower and fruit. Take pictures. Note insects and diseases. All this information will guide you in seasons to come.

Indoor Plant and Insect Tips

  • Begin to fertilize houseplants again. The increase in natural light will prompt them to grow.
  • This is a good time to repot and divide houseplants. Use lightweight, well-drained soilless potting mixes that contain ingredients such as peat moss, vermiculite, and perlite.
  • Several species of insects are waking up from their winter dormancy inside homes. The earliest ones are multicolored Asian lady beetlemarmorated stink bugcluster flies, and boxelder bugs. No chemical controls are recommended. They are harmless and can be swept up, vacuumed, scooped into a container of soapy water, or released outdoors.


For more information call or email the University of Maryland Extension Queen Anne’s County Master Gardener Coordinator, Rachel Rhodes, at 410-758-0166 or . Rachel J. Rhodes is the Horticulture Educator and Master Gardener Coordinator for the University of Maryland Extension in Queen Anne’s County. She is one third of the Garden Thyme Podcast. The Garden Thyme Podcast is a monthly podcast where University of Maryland Extension Educators, help you get down and dirty in your garden, with timely gardening tips, information about native plants, and more! For further information, please visit or see us on Facebook @ or listen to The Garden Thyme Podcast at:


Soil: (Photo Credit: Lee Schnappinger Bridgman) If you did not test soil in fall, as soon as ground thaws, take soil samples from different parts of the garden, to a depth of 6 to 8 inches. Send to a soil testing lab (University of Maryland’s Home and Garden Information Center,, tells how to take samples and lists regional lab; see “Selecting Soil Test Lab,” HG#110.)


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