Plant seeds of cool-weather vegetables such as peas, spinach, lettuce, potatoes, turnips and radishes directly in the ground around St. Patrick's Day in central Maryland. Plant carrots, chard, endive, kale, leeks, romaine and parsley around April 1.
Start tender vegetable seedlings such as tomatoes, peppers, eggplants, cabbage, cauliflower and collards four to six weeks ahead of the last frost date for your area of Maryland, which typically occurs at the end of April or beginning of May in central counties. Transplant them outside a week or two after the last frost date, when the soil has warmed thoroughly.
Plant seeds of beans, canteloupes, cucumbers, squash, corn, watermelons and other warm-weather vegetables directly in the ground after the last frost date when the soil has warmed thoroughly, around mid-May.
Examine seedlings bought from garden centers closely to make certain they are healthy and that their roots do not encircle the bottom of the pot.
Harden off homegrown or store-bought seedlings prior to planting. Expose them gradually to outdoor conditions during the daytime for a week before final planting.
Transplant vegetables on a cloudy, warm afternoon and water well. Dig holes for each seedling, place it in the hole and gently firm the soil around the roots and stem. Place tomatoes deeply in the hole, up to their first set of true leaves, and cover so that new roots emerge from the stem.
Apply starter fertilizers to the foliage or root-zone of spring crops to get them off to a fast start, the Maryland Cooperative Extension advises.
Plant vegetables in containers in urban and suburban areas of Maryland, where open ground is scarcer. Horticulturalists at the state extension service recommend planting salad greens, peppers, eggplant, tomatoes, beans, chard, beets, radishes, squash and cucumbers. Use bush or dwarf varieties of tomatoes and cucumbers for 5-gallon buckets; plant full-size versions in 20-gallon tubs.
Follow three-season planting or succession planting in containers, beginning with spring lettuce or radish, followed by peppers, beans or cucumbers in late May and finally planting kale, lettuce or broccoli in the fall.
Fertilize each container crop with worm compost or granular fertilizer, according to directions on product. Apply starter fertilizers to the foliage or root-zone of spring crops to get them off to a fast start, the Maryland Cooperative Extension advises.