March Gardening Calendar
Published: February 17, 2020
- Two handsome houseplants that provide fragrant blossoms indoors this month are the Confederate jasmine (Trachelospermum jasminoides) and Japanese pittosporum (Pittosporum tobira). Both thrive in average home conditions and are easy plants to grow.
- As day lengths increase, plants begin new growth. Repot rootbound plants, moving them to containers 2 inches larger in diameter than their current pot. Check for insect activity and apply controls as needed. Leggy plants may be pruned now.
- Trees, shrubs and perennials may be planted as soon as they become available at local nurseries.
- To control iris borer, clean up and destroy the old foliage before new growth begins.
- Fertilize bulbs with a "bulb booster" formulation broadcast over the planting beds. Hose off any granules that stick to the foliage.
- Dormant mail order plants should be unwrapped immediately. Keep the roots from drying out, store in a cool protected spot, and plant as soon as conditions allow.
- Loosen winter mulches from perennials cautiously. Re-cover plants at night if frost returns. Clean up beds by removing all weeds and dead foliage at this time.
- Heavy pruning of trees should be complete before growth occurs. Trees should not be pruned while the new leaves are growing.
- Seeds of hardy annuals such as larkspur, bachelor's buttons, Shirley and California poppies should be direct sown in the garden now.
- Summer and fall blooming perennials should be divided in spring.
- Ornamental grasses should be cut to the ground just as the new growth begins.
- Spring bedding plants, such as pansies and toadflax (Linaria sp.), may be planted outdoors now.
- Apply a balanced fertilizer such as 6-12-12 to perennial beds when new growth appears.
- Apply sulfur to the soils around acid-loving plants such as azaleas, rhododendrons, hollies and dogwoods. Use a granular formulation at the rate of 1/2 pound per 100 square feet.
- Gradually start to pull back mulch from rose bushes.
- Mow lawns low to remove old growth before new growth begins.
- Apply broadleaf herbicides now for control of cool-season perennial and annual weeds. These must not be applied to areas that will be seeded soon.
- Apply controls for wild garlic. It will take several years of annual applications for complete control.
- Thin spots and bare patches in the lawn can be overseeded now.
- Any root crops such as horseradish, parsnips, Jerusalem artichokes, or carrots still in the ground from last year should be harvested before new green top growth appears.
- Cultivate weeds and remove the old, dead stalks of last year's growth from the asparagus bed before the new spears emerge.
- Fertilize the garden as the soil is being prepared for planting. Unless directed otherwise by a soil test, 1 to 2 pounds of 12-12-12 or an equivalent fertilizer per 100 square feet is usually sufficient.
- Delay planting if the garden soil is too wet. When a ball of soil crumbles easily after being squeezed together in your hand, it is dry enough to be safely worked.
- Asparagus and rhubarb roots should be planted as soon as the ground can be worked.
- Plant peas, lettuce, radishes, kohlrabi, mustard greens, collards, turnips, Irish potatoes, spinach and onions (seeds and sets) outdoors.
- Plant beets, carrots, parsley and parsnip seeds outdoors.
- Set out broccoli, cabbage, Brussels sprouts, Chinese cabbage and cauliflower transplants into the garden.
- Start seeds of tomatoes, peppers and eggplants indoors.
- Gradually remove mulch from strawberries as the weather begins to warm.
- Continue pruning apple trees. Burn or destroy all prunings to minimize insect or disease occurrence.
- Continue pruning grapes. Bleeding causes no injury to the vines. Tie vines to the trellis before the buds swell to prevent bud injury and crop loss.
- Cleft and splice grafting can be done now. This must be completed before rootstocks break dormancy.
- Aphids begin to hatch on fruit trees as the buds begin to open.
- Apply dormant oil sprays now. Choose a dry day when freezing temperatures are not expected.
- Spray peach trees with a fungicide for the control of peach leaf curl disease.
- Mulch all bramble fruits for weed control.
- Peaches and nectarines should be pruned just before they bloom.
- Red maples begin to bloom.
- Set up nesting boxes for bluebirds.
- Watch for the harbinger of spring (Erigenia bulbosa) blooming in rich wooded areas.
- Spicebush is blooming in moist woodlands.
- Raise purple martin houses this week.
- Purple martins return to the St. Louis area.
- The white flowers of serviceberry (Amelanchier sp.) and wild plum (Prunus americana) are showy in wooded areas.
- Watch for the fuzzy blooms of the pussy willow (Salix sp.).
Gardening Calendar supplied by the staff of the William T. Kemper Center for Home Gardening located at the Missouri Botanical Garden in St. Louis, Missouri. (www.GardeningHelp.org)