March is a month of great transition in the vegetable garden. Spring for the northern hemisphere will arrive on March 20.
In the warmest regions–United States Department of Agriculture (USDA) Plant Hardiness Zones 9 through 11–warming temperatures have arrived. Planting can go forward this month. In USDA Zones 7 and 8, preparation for spring planting can begin in earnest this month, but sowing and transplanting out into the garden may be delayed by continuing cold weather. In USDA, Zones 6, 5, 4, and 3, winter weather and cold temperatures will likely keep you out of the garden this month.
In the United States, USDA Zones 10 and 9 include the Gulf Coast and parts of the South Atlantic states, the Pacific Southwest—mainly Southern California, and parts of the Desert states. Temperature lows in the coldest of these regions can drop as low as 20°F (-7°C). In Europe, parts of Spain, Italy, and France and regions of countries bordering the Mediterranean Sea are in Zones 10 and 9.
USDA Zone 8 includes the Mid-South, Pacific Norwest states, and parts of Northern California. Zone 7 includes parts of the Northeast, Mid-Atlantic region, and eastern sections of the Northwest. Temperature lows in the coldest of these regions can drop as low as 0°F (-18°C). Much of the United Kingdom, France and parts of Spain are in Zone 8. The western regions of Germany are in Zone 7.
USDA Zones 6, 5, 4, and 3 are the most northern and coldest winter regions of the country, the northern parts of the Rocky Mountains, northern Plains and the Midwest states, and the northern regions of the Northeast and into Canada. . Temperature lows in the coldest of these regions can drop as low as -40°F (-40°C). Eastern Europe is largely Zone 6 and Zone 5.
Here is a checklist of things to do in the vegetable garden during March in the Northern Hemisphere beginning with the warmest regions:
USDA Zones 9-11 Vegetable Garden Calendar:
Winter temperature lows in Zone 10 can drop to 30°F (-1°C); in Zone 9 winter lows can drop to 20°F (-7°C).
Vegetables. Harden off vegetable seedlings in the cold frame before planting them out in the garden.
Plant out cool- and warm-season vegetables and herbs. (Don’t rush planting out of summer crops unless the weather has turned warm.) Plant asparagus, beets, beans, cabbage, carrots, casaba, corn, cucumbers, eggplant, kale, lettuce, melons, okra, onions, onion sets, parsley, parsnip, peas, potatoes, pumpkin, radishes, salsify, summer spinach, squash, tomatoes.
Spade a rich compost into areas to be planted at least a week in advance of planting. For tomatoes, select a location where they have not been grown for a year or more.
Fruit Trees and Berries. Fruit trees are in bloom now. Fertilize fruit trees and vines. Plant citrus trees now.
Set out new strawberry plants. In six weeks, feed them with fish emulsion or rich compost. Pick off all flowers until mid-June.
Raspberries require more water than other cane berries because they root more shallowly. When set out, cut canes off to 4 to 6 inches (10-15 cm). When new growth is 1 foot (30 cm) high, nip off 2 inches (5 cm) to cause branching. Tie up berry canes for easier harvesting.
Lemon trees can become infested with red scale. Apply an oil emulsion spray before April.
A common problem found in berry plants is red-berry mites, which attack the developing blossom so that sections of fruit never ripen. Complete control is possible only in spring. Spray berries pruned in March with a lime-sulfur mix.
Grapes. Tie up branches of vines planted last year. Provide support for those planted this year. Cut off all branches when planting, allowing only one cane to develop.
Zones 7-8 Vegetable Garden Calendar:
Winter temperature lows in Zone 8 can drop to 10°F (-12°C); in Zone 7 winter lows can drop to 0°F (-18°C).
Soil preparation. Prepare beds and planting holes as soon as the ground can be worked. Also, dig up root crops left in the garden from last fall.
Fork over the kitchen garden, dig in cover crops, remove weeds, rake the soil to a fine tilth, and spread compost if the soil is dry enough to cultivate. Prepare celery and potato trenches by adding a layer of well-rotted manure or garden compost to the trench area.
Remove winter mulch from around fruit trees, vines, and perennial vegetables that are flowering or have begun to sprout new growth.
Begin a new compost pile during the spring if you don’t already have one. Use leftover leaves, grass, and non-fatty kitchen scraps.
Greenhouse and cold frame. If the weather remains chilly in your region, sow tender summer vegetables and herbs in the greenhouse or cold frame this month. Hardy and half-hardy vegetable starts should be ready for the cold frame now in less cold regions, having been sown last month. Start the seeds of summer vegetables that require 8 weeks or more indoors before transplanting out. Warm-weather summer crops include basil, eggplant, peppers, squash, and tomatoes.
Thin seedlings that have grown to size, pot them up, and place them in the cold frame or plant them out later this month.
Ventilate the greenhouse and cold frame when the outside temperature rises above 40ºF (4ºC). Close again before sundown. Ventilation should be increased on warm days as much as possible to prevent the buildup of diseases in the damp atmosphere. Check plants for signs of pests and disease, which often begin to multiply rapidly as the temperatures rise. Water seedlings and plants as needed. If you are going to plant vegetables in the frame, fork over the soil and add amendments that will ensure that the soil is light and loamy. You can start tender seeds, cabbage family members, tomatoes, peppers, and eggplant in the hotbed or cold frame this month.
Container gardens. If you garden in containers, prepare them now. Clean pots thoroughly. Treat wooden boxes, troughs, and tubs with preservatives. Move large containers outdoors and fill them with potting mix mixed with compost.
Cold-tolerant vegetables can be planted into containers this month. Water container plants as needed and fertilize them with a water-soluble fertilizer such as compost tea or worm castings.
Vegetables outdoors. When the danger of heavy frost is past begin sowing cool-weather crops. You can first warm up the soil by covering it with polyethylene or cloches. Cover vegetables already in the garden with horticultural fleece or floating cloches if you expect frost.
Start sowing vegetables without protection if you live in a mild area or your weather has warmed. If you are in doubt, check your soil with a soil thermometer to make sure the soil temperature has warmed to greater than 45ºF (7ºC). Few seeds will germinate if the soil temperature is colder. Delay planting outdoors if the soil is too cold.
Set out quick-growing cool-weather transplants and sow leaf and flower vegetable seeds as soon as the danger of heavy frost is past. Cool-weather leaf and flower crops include bok choy, broad beans, broccoli, Brussels sprouts, cabbage, cauliflower, chard, kale, lettuce, peas, and spinach. Cool-season root crops can also be planted out in the garden if the soil is not excessively wet. These include beets, carrots, kohlrabi, leeks, onion sets, parsnips, early potatoes, radishes, scallions, shallots, and turnips.
- Asparagus: Get asparagus crowns in the ground now. Remember these roots need to be planted in an area set aside for their growth over several seasons. Top asparagus crowns with well-rotted compost.
- Beets: Soak seed overnight in lukewarm water, drain, place seed 1 inch (2.5 cm) deep and 1 inch apart. Cover with loose soil, firm. Break crust formed by beating rains with gentle action of rake. If transplanting: transplant seedlings when 3 inches (7.5 cm) tall, leaving plants 3 inches apart. Cabbage: Plants should be set 18 inches (45 cm) apart. Firm soil, and water each plant. Do not sow cabbage seed this late.
- Carrots: Seed must be covered very lightly–¼ inch (6 mm) is too much. A few radish seeds sown in the carrot row help mark the row until the carrot is up. Sow seed thinly and thin established plants to 3 inches.
- Chard: seed planted like beets, thin to 12 inches (30 cm).
- Peas: Best planted 1 inch apart, 2 inches (5 cm) deep, 12 inches from next row. Plant at least two varieties for extended production.
- Potatoes: Plant right away. Use certified seed and plant on new potato ground.
- Radishes, spinach, and turnips: Plant now.
- Herbs: Sow herbs in the garden now. Sow seeds of chervil, dill, fennel, parsley, pot marjoram, and sorrel. Perennial and biennial herbs can be lifted, divided, and replanted now. Look for any overgrown clumps of bergamot, chives, and fennel.
In areas where the daytime temperature now averages 65ºF (18ºC) or greater, warm-weather crops can be sown or transplanted out. Warm-weather crops include basil, beans, corn, cucumbers, eggplant, peppers, melons, squash, and tomatoes.
Feed perennial vegetables with well-rotted compost and compost tea after they begin to grow. Keep the garden free of weeds. Apply summer mulch when the weather warms.
Water in dry regions regularly and deeply. Avoid wetting the plant foliage. Protect recently planted vegetables and herbs from drying winds.
Harvest cool-weather crops as soon as they are ready. Begin to harvest spears from two- and three-year-old asparagus plants this month.
Before slugs, snails, and pillbugs invade your leafy greens, head them off with beer traps.
Fruit trees and vines. If you are in a cool region and your fruit trees have swollen buds that have not broken, you may still have time to spray for over-wintering pests with dormant spray oil. Spray when the temperature rises above 45ºF (7ºC), but while plants are still dormant. Spray peaches, nectarines, apples, pears, plums, and almonds with a copper-based fungicide. As long as the buds have not broken, apply a second spray to trees in about 14 days. . This is the last chance to prune winter-damaged fruit trees. Limit pruning of spring-flowering fruit trees to the removal of suckers and winter-damaged or crossing branches to save blossom buds.
Plant new fruit trees, avocadoes, and citrus fruit when the soil is workable. Mulch established fruit trees and bushes with garden compost or well-rotted manure.
Sprinkle sulfate of potash around the root-feeding area of apples, pears, and plums to encourage good fruiting later in the year.
Prune autumn-fruiting raspberries. Cut the canes that fruited last autumn back to ground level. Prune back the stems of newly planted and two-year-old gooseberries by about one-half. Plant currant bushes and raspberry canes, and water in thoroughly. Spray gooseberries and black currants for gooseberry mildew. Protect strawberry plants with cloches.
Fertilize rhubarb, strawberries, berries, brambles, grapevines, and figs with compost when the first blossoms show.
Train blackberries and loganberries onto support wires.
Zones 3-6 Vegetable Garden Calendar:
Winter temperature lows in Zone 6 can drop t0 -10°F (-23°C); Zone 5 lows can drop to -20°F (-28°C); Zone 4 lows can drop to -30°F (-34°C); Zone 3 lows can drop to -40°F (-40°C).
Plan and design. Map where snow melts first in the garden and mark these spots for planting early crops.
Planting bed and soil preparation. As soon as the soil is dry enough to work, clean up the garden and prepare the soil for planting cool-weather crops. First, remove any winter debris or winter mulches, then take a soil sample and have it tested. You can renew most vegetable growing beds by simply adding well-rotted manure and compost.
Few seeds will germinate in cold soil where the temperature is below 45ºF (7ºC). Use a soil thermometer to check how warm your soil is.
Greenhouse, cold frame, and hotbeds. Check seed packets to determine the number of days from sowing to germination. Sow vegetables about six weeks before seedlings can be hardened off in a cold frame, but do not start seeds indoors too early.
Start cool-weather crops indoors first: broccoli, Brussels sprouts, cabbage, cauliflower, celery, leeks, onions, and parsley. Late in the month, move these cool-weather seedlings to a cold frame to harden them off before planting them out.
Start less hardy crops indoors beginning after the middle of the month: beets, carrots, lettuce, peas, potatoes, radishes, and spinach. These seeds require 8 to 10 weeks or more indoors.
At the end of the month or early in April, sow tender summer crops indoors: tomatoes, eggplant, squash, and herbs. Use individual peat pots for squash.
Seedlings started in a windowsill should be turned daily, watered, and fertilized as necessary. If seedlings are growing under lights be sure to adjust the height of the lights as necessary. Pick out or pot up seedlings sown earlier. Put seed potatoes in a warm, bright, windowsill to encourage them to sprout.
Be sure to increase greenhouse ventilation on warm days. Check greenhouse plants for signs of pests and disease which can multiply as the temperatures rise.
Ventilate the cold frame when the temperature is above 45°F (7°C). Be sure to close frames before evening and night temperatures drop too low. Cover frames with an old blanket or straw when a freeze threatens or in drying winds.
If you are going to plant vegetables in the frame, fork over the soil and add amendments that will ensure that the soil is light and loamy. Start tender seeds in the hotbed toward the end of the month. You can start cabbage and other cabbage family members, tomatoes, peppers, and eggplant in the hotbed this month.
Planting out vegetables and herbs. When the soil begins to warm and becomes workable, direct-sow early hardy crops: beets, broad beans, Brussels sprouts, broccoli, carrots, cauliflower, celery, chard, lettuce, onions, parsnips, peas, radishes, spinach, and turnips. Plant early potatoes and onion sets. Later in the month, make a second sowing of early peas in areas where the temperature has moderated. Be sure to set up supports for peas.
Cover outdoor seedlings if you expect a heavy frost.
Dig compost and well-rotted manure into celery trenches and runner-bean trenches.
Late in the month, you can start warm-season vegetable seeds indoors: tomatoes, eggplant, and squash. Start seeds indoors in flats, give them full sunlight, and then be sure to transplant them to pots as soon as they become crowded or get their second pair of leaves.
Perennial vegetables. Remove winter mulches from perennial vegetable beds and clean up any debris. Fertilize established asparagus and rhubarb beds with compost as they begin to grow. Plant new asparagus and rhubarb beds this month; add aged compost to old asparagus and rhubarb beds.
Fruit trees and vines. Gradually remove all winter mulches and burlap wrappings from around fruit trees and vines. Clean up any dropped fruit and leaves from last season.
Prune apples, pears, and other fruit trees, grapes, and berries before new growth begins. Prune out winter damage and complete pruning while plants are still dormant. Limit pruning of spring-flowering fruit trees to the removal of suckers and winter-damaged or crossing branches to save blossom buds.
Apply dormant sprays to fruit trees before they come into growth. Dormant oil sprays or horticultural oil should be applied when the temperature is above 40ºF (4ºC). Spray apples and pears prone to scab infection. Spray gooseberries and black currants for gooseberry mildew.
Plant deciduous fruit trees while dormant. Plant bare-root, balled-and-burlapped, and container trees as soon as the soil can be worked. Install supports for newly planted trees. If bare-root trees and vines can’t be planted right away, heel them into trenches to keep their roots moist.
When the ground is workable, plant bare-root berry bushes, grapevines, and asparagus. Plant currant bushes and raspberry canes and water in thoroughly.
Prune back the stems of newly planted and two-year-old gooseberries by about one-half. Prune and thin brambles if not done last fall; reapply mulch.
As the snow disappears, gradually remove mulch from established strawberries and begin covering them with row covers to encourage early blooming. Remove or replace strawberries heaved by frost. You can protect strawberry plants from frost and freezing weather with cloches.