Starting vegetables from seed is rewarding work, and it's a lot cheaper than buying transplants of everything at the garden center. When you start your own seeds, you have access to a wider variety of vegetables, and the plants you grow will be stronger than those started in a greenhouse. You also have the ability to choose which, if any, chemicals and soil additives your plants are exposed to.
Heirloom vegetables are old-fashioned, open-pollinated varieties of plants that have been passed down for generations---or even for centuries. Heirloom vegetables don't travel as well as modern hybrids and are as uniform-looking, but they are far and away more flavorful, nutritious and colorful, and they are perfect to grow in the home kitchen garden.
Most varieties of heirloom vegetables are available only as seeds, from heirloom vegetable catalogs or from seed saver's exchanges---or, if you're lucky, from your grandma, or the old farmer down the street. By growing heirloom vegetables from seed, you can taste the exact varieties of food that nourished your ancestors, and you can help preserve the genes of that vegetable for another generation.
Most nurseries or garden centers may only stock four or five varieties of winter squash, but if you flip though any seed catalog you'll find dozens, even hundreds of varieties---big ones, little ones, orange ones, blue ones, smooth ones, bumpy ones, and on and on.
A nursery can only afford to sell transplants of their biggest sellers, so if you want to grow a rare variety of Mexican chili peppers or an exotic eggplant imported from China, your best bet is to start your own from seed.
It can be tempting to stock up on those cute little six-packs of basil or parsley at the garden center, but it is much more cost-efficient to start your own herbs from seed, especially for herbs that you use a lot of or that you would like to preserve. Stagger the planting of annual herbs like basil, dill and savory so that you'll have fresh herbs ready to harvest every few weeks.
Grow biennial or perennial herbs like parsley, chives, lavender, mint and thyme in containers to bring indoors in the winter. If you have a greenhouse, or a warm south-facing window, you can grow annual herbs in the winter, too, if you start the seeds in late summer or early autumn.
Direct Sown Vegetables
Some vegetables, like radishes, are so fast growing that it only makes sense to start them from seed. Many salad greens, like lettuce, arugula and cress also grow quickly from seed. Other plants are a bit fussy about being transplanted, and are healthier and stronger if they are grown from seed directly in the garden.
Start carrots, Swiss chard, beets, parsnips and turnips a week or two before your local predicted frost free date. Beans, peas and corn should be started just after the last frost.