Growing your own vegetables like tomatoes, peppers and eggplants from seed gives you the satisfaction of knowing you were involved from start to that moment when you serve a dish full of vegetables you raised and prepared. Growing from seed allows you a much wider range of varieties than you would normally find at the nursery, so you can experiment with heirlooms, open-pollinated varieties, or even seeds you kept from previous harvests. In the Southwest, December is the time to get the process started.
When you're ready to plant, fill a clean container with potting mix, such as Miracle-Gro® Seed Starting Potting Mix. Water well and firm the mix by gently pressing on it. Use a container that drains, but is no more than 2 inches deep. Drop seeds on the top of the potting mix, pressing them in with a small tool like the eraser end of a pencil or a chopstick and lightly cover the seeds. Plant most vegetable seeds 1/4 inch or less below the surface. Place the pot in a warm, sunny, location and cover it with a clear, plastic storage bag (freezer bags are not recommended; they are not porous enough.) Water only when the surface of the potting mix is dry or you see no water droplets on the covering.
Germination depends on temperature but should take no longer than 4 to 6 weeks after planting (in most cases, your seeds will germinate in 1 to 2 weeks). Once the seedlings have germinated, take off the covering and move the plants to a warm, protected location that has strong but indirect light to prevent them from becoming leggy (weak-stemmed). Once your seedlings have 2 true leaves, feed weekly with a diluted solution of water-soluble plant food, such as Miracle-Gro® Water Soluble All Purpose Plant Food, until you’re ready to transplant (after the last frost).
Most greens are fast-growing enough to plant in succession at 2- to 3-week intervals, staggering starts so you have a continual supply of greens. Good choices include lettuce, spinach and Swiss chard. Oriental greens like Chinese cabbage, bok choy, and tatsoi are quick-maturing greens that are ideal for succession plantings. Radish in any variety and turnips, especially 'Tokyo Cross', are also fast-maturing and easy to plant in December.
Fast-growing plants aren't the only element of winter gardening. Slower-maturing crops like beets, broccoli, parsley, dill, fennel, carrots--as well as transplants of artichoke, both Chinese and garlic chives, bunching onions, and mints--can also be planted in December.
This is the beginning of the coldest time of the year, even in the warm desert, so it’s important to adjust watering schedules for vegetables. Water to a depth of 8-12 inches, but reduce the frequency. Allow the top several inches of soil to dry between waterings.