This photo is of a double blue primrose seedling, blooming now in Corvallis, Oregon.
March is a very busy month for gardeners. Root crops stored from the previous year and planned to produce seed can be planted out late in the month after the soil thaws (cabbages, celery, lettuce, leeks, onions, parsnips). Planting time will arrive soon, or has already arrived for those of you in mild climates. Weed and clean borders and vegetable beds, plant perennials, sow seeds of hardy annuals, plant rhubarb, asparagus, sea kale and artichokes. Plant and/or prune cane fruits and fruit trees (cherries, apples, peaches, apricots, pears, plums, currants, gooseberries, etc.). Check cold frames on a regular basis, venting as needed and closing the glazing panels at night. Watch temperatures in the greenhouse also, as March is a month of ups and downs in temperature. Manure and other organic soil amendments (epsom salts, seaweed meal, alfalfa meal, greensand, bone meal, compost and wood ashes) can be spread over vegetable, fruit, flower and rose beds. Grape vines can be manured now, leaving space around the stem; treat roses in the same manner.
Many vegetables can be sown indoors now for transplanting out later: cole crops (brassicas), onions, lettuce, peppers, eggplant and leeks. Some vegetables can be direct sown outside if weather permits and if your soil is not too wet to work: arugula, carrots, corn salad, fava beans, cress, mustard and turnip greens, onions, peas, radishes and spinach. Celery and lettuce can be direct sown into frames. Several vegetables and fruits can be transplanted now: raspberries, blackberries, strawberries, asparagus, horseradish, head lettuce, onion sets and plants and perennial herbs. Make sure your mushroom beds do not get too wet; replace straw if wet.
Potted auricula primroses should be protected from rain and frosts; they will begin to bud soon. Sow any remaining auricula and primrose seeds. Herbaceous perennials can be divided and planted now. Many hardy annual flowers may be sown during March: larkspur, sweet peas, lychnis, nigella, lavatera, poppies, kiss-me-by-the-garden-gate and sweet alyssum. Inside the greenhouse sow: petunias, impatiens, pansies, alyssum, chrysanthemums, iceplants, portulacas, salvias, snapdragons, sweet Williams, ten-week stocks, mignonette, hesperis, Shasta daisies, hibiscus, lupine and Salvia x superba.
Roses and other shrubs may be layered now, and cuttings may be made of geraniums, myrtles and hydrangeas. If you want to plant a hedge from seed, now is the time to sow seeds of hawthorns, stone fruits, roses and other hardy shrubs you might like to use. The young plants can be transplanted out to their permanent positions later.