Seed Starting Vegetables in March

Squash seed startingTo get a head start on the growing season: start your vegetable seeds indoors. Cold soil and unsettled weather will challenge seeds sown directly in the garden in early spring.

For early cool-season crops try indoor seed starting this year; you can get started this month. Crops that are the easiest to start indoors from seed are broccoli, Brussels sprouts, cabbage, cauliflower, leeks, lettuce, onions, peppers, and tomatoes.

Start warm-season crops indoors 6 to 8 weeks before you plan to set them into the garden: beans, cucumbers, eggplant, melons, tomatoes, and squash are best started in bio-degradable peat or paper pots that can be planted whole into the garden (that way you won’t disturb their roots at transplanting).

Checklist of supplies you will need to start seed indoors:

□ Containers: flats or individual containers at least 3 to 4 inches deep.

□ Seed-starting and potting mixes: peat moss, fine compost, perlite, and milled sphagnum moss will work for seed starting. Later you will need a potting mix: 1 part garden soil, 1 part perlite or builders’ sand; 1 part fine compost.

□ Lights: adjustable up and down fluorescent lights will do to keep plants growing.

□ Capillary mats placed under containers will wick up moisture to the seeds and seedlings.

□ Half-strength fertilizer to get seedlings growing: fish or seaweed fertilizer or compost tea.

Seed starting guide for March by USDA Plant Hardiness Zones, warmest zones first:

Zone 10: (Where the annual low temperatures can reach 30°F /-1°C.)

□ Direct-sow in the garden and transplant out spring crops; leafy vegetables and root vegetables.

□ Sow out summer vegetables and tender herbs when frost danger is past: basil, beans, corn, cucumbers, and melons.

□ Set out in the garden tomato and pepper transplants.

□ Plant tender summer vegetables and herbs in containers

□ Thin seedlings.

Zone 9:  (Where the annual low temperatures can reach 20°F /-7°C.)

□ Make last sowings of cool-season root crops: carrots, beets, broad beans, Brussels sprouts, carrots, cauliflower, onions, parsnips, radishes, and spinach.

□ Plant early potatoes, onion sets, and shallots.

□ Make a second sowing of early peas.

□ Direct-sow and transplant out warm-weather crops; check seed packets, some varieties are well suited for early sowing.

□ Warm up the soil for warm-weather crops with plastic sheeting, horticultural fleece, or cloches.

□ Sow sunflowers and nasturtium seeds outdoors.

□ Start eggplant seedlings and sweet potato slips indoors.

□ Thin seedlings.

Zone 8:  (Where the annual low temperatures can reach 10°F /-12°C.) 

□ Prepare planting beds when the soil can be worked; remove weeds, rake soil to a fine tilth, and add aged compost.

□ When the soil is dry and workable, plant asparagus crowns, onion sets, and early potatoes.

□ Prepare potato trenches adding a layer of well-rotted manure or aged compost. Plant early potatoes.

□ Top-dress asparagus beds with well-rotted manure or aged compost.

□ Sow in the garden beets, broad beans, Brussels sprouts, carrots, cauliflower, kohlrabi, lettuce, green and spring onions, parsnips, peas, radishes, shallots, spinach, and turnips.

□ Plant new strawberries; put cloches over strawberries if you want an early cop.

□ Sow out herbs: chervil, dill, fennel, parsley, pot marjoram, and sorrel.

□ Lift and divide over-grown clumps of bergamot, chives, and fennel.

□ Direct sow nasturtiums.

□ Dig well-rotted manure into celery trenches.

□ Prepare runner-bean trenches by digging in compost or well-rotted manure.

□ Late in the month, sow indoors tomatoes, peppers, and eggplant; also start sweet potato slips indoors. Adjust the height of seed-starting lights or turn seedlings in the windowsill daily; water and fertilize indoor seedlings.

□ Warm up the soil with cloches or horticultural fleece.

Zone 7:  (Where the annual low temperatures can reach 10°F /-12°C.) 

□ Finish winter digging; add aged compost to planting beds.

□ Place cloches or plastic tunnels in position to warm up the soil.

□ Sow early crops in cold frames or beneath cloches or horticultural fleece if hard freezes are still about.

□ Sow beets, Brussels sprouts, carrots, chard, dill, parsley, onions, parsnips, radishes, and spinach.

□ Sow broad beans under cloches.

□ Sow early peas in a sheltered sport; make a second sowing in two weeks.

□ Plant early potatoes and onion sets.

□ Sow onion and scallion seed. Set out onion and scallion sets.

□ Transplant cabbage, broccoli, and onions to the garden; cover them with cloches if you expect a hard frost or leave the cloches in place for a few weeks.

□ Chit (sprout) ‘seed’ potatoes (small tubers) of early varieties and prepare to plant.

□ Start indoors seed of tomatoes, peppers, eggplant, and basil.

□ Prepare runner bean and celery trenches; dig well-rotted manure into celery trenches.

□ Begin sowing herbs in a warm cold frame or green house.

Zone 6:  (Where the annual low temperatures can reach 10°F /-12°C.)

□ Dig in cover crops as soon as the soil can be worked.

□ Finish winter digging; add aged compost to planting beds.

□ Place cloches or plastic tunnels in position to warm up the soil.

□ Move broccoli, cabbage, and cauliflower seedlings to a coldframe.

□ Sow beets, Brussels sprouts, carrots, chard, dill, parsley, onions, parsnips, radishes, and spinach; cover beds with horticultural fleece if hard frosts persist.

□ Sow broad beans under cloches.

□ Sow early peas in a sheltered spot; make a second sowing in two weeks.

□ Plant early potatoes and onion sets.

□ Sow onion and scallion seed. Set out onion and scallion sets.

□ Transplant cabbage, broccoli, and onions to the garden; cover them with cloches if you expect a hard frost or leave the cloches in place for a few weeks.

□ Chit (sprout) ‘seed’ potatoes (small tubers) of early varieties and prepare to plant.

□ Start indoors seed of tomatoes, peppers, eggplant, and basil.

□ Prepare runner bean and celery trenches; dig well-rotted manure into celery trenches.

□ Begin sowing herbs in a warm cold frame or green house.

Zone 5:  (Where the annual low temperatures can reach to -20°F /-28°C.)

□ Dig root crops left in garden from last fall.

□ Clean up garden and prepare soil for planting later crops.

□ Prepare planting beds for cool-weather crops as soon as the soil is dry enough to work.

□ Plant new asparagus and rhubarb beds, fertilize established ones with a blanket of compost

□ Prepare soil and direct-sow earliest crops as soon as soil is workable.

□ Care for indoor seedlings; adjust height of lights, turn windowsill seedlings daily, water, fertilize.

□ Put seed potatoes in a warm, bright windowsill to encourage them to sprout

□ At the end of the month, move broccoli, cabbage, and cauliflower transplants outdoors to a cold frame. Cover the frame with a blanket or tarp if a hard freeze threatens.

□ Start tomato and pepper seeds indoors this month.

Zone 4 and 3:  (Where the annual low temperature can reach -30°F /-34°C in Zone 4 and -40°F /-40°C in Zone 3.)

□ Clean up garden areas for later planting.

□ Start cabbage, broccoli, Brussels sprouts, cauliflower, celery, leeks, onions, and parsley indoors beneath lights.

□ Trim the tops of onion and leek seedlings to an inch or so high, to keep them stocky.

□ Direct-sow earliest crops when soil begins to warm.

□ At month’s end, start sprouting spinach and lettuce indoors.

□ Late in the month, start seeds tomatoes, peppers, and eggplants indoors; use individual peat pots.

Grow 80 vegetables: THE KITCHEN GARDEN GROWERS’ GUIDE