You can start most vegetables from seeds, but some of them are best left to the experts who germinate them under special conditions and then offer starter plants for sale. Some vegetables, such as asparagus, broccoli and Brussels sprouts, can take quite a long time to grow to maturity; others, such as peppers and eggplant, require heat, special grow lights or other help to get them to sprout, grow and produce their harvest.
You can direct sow asparagus seeds in your garden, but don't expect them to begin producing tender, edible spears for up to two years after you plant them. According to Ohio State University, you must plant asparagus seeds in sandy loam soil and then dig up and transplant the "crowns" the following year. Ag-Ohio also advises that you treat asparagus seed with bleach to control asparagus root rot. If you plant asparagus seeds in a prepared mixture in nursery flats, use a special blend of soil, peat and sand. A planting depth of ½ to 5/8 inch per seed is also very important.
The University of Missouri website recommends that you start broccoli seeds in an area where you can control the temperature---they state it is best to keep flats containing broccoli seeds at around 55 degrees F and then increase the temperature to 65 to 75 degrees F after the seeds have germinated. It's also good, they say, to cover your flat with plastic to keep in moisture, but avoid putting a covered flat in direct sun because it can get too hot for the newly sprouted broccoli. After seeds have germinated, move your flat to an area that receives direct sun, but not hot sun. Be very careful not to allow the soil to dry out, because young seedlings can easily die from lack of moisture.
The University of Illinois reports that you must start Brussels sprouts seeds in flats in a protected location about five to six weeks before you transplant young plants to the garden. Calculate when your first fall frost will occur and then plant your Brussels sprouts 90 to 100 days before that date. If you live in an area where the summers are quite hot, purchase seeds of a heat-resistant variety of Brussels sprouts. They are a cold-hardy but slow-growing vegetable, so don't expect your plants to produce Brussels sprouts their first season in the ground.
Peppers and Eggplants
If you live in the Deep South, Hawaii, Puerto Rico or another tropical climate, peppers and eggplants are easier to start from seed than if you live farther north. The National Gardening Association suggests that gardeners in northern states purchase starter plants of these vegetables. It's possible to start these two nightshade family vegetables from seed in all climate zones if you begin with sterilized potting soil, a flat with drainage holes, grow lights and a source of heat---bottom heat in the form of a plant heating pad works very well. Avoid overwatering to prevent a condition known as damping off, where the fragile young stems of your seedlings rot at the soil line. Don't place your flat full of pepper or eggplant seeds in the hot sun---grow lights are preferable because they can't burn seedlings.