(Editor's Note: This article was originally published on March 8, 2009.Your comments are welcome, but please be aware that authors of previously published articles may not be able to promptly respond to new questions or comments.)
Many of these vegetables are direct-sowed, which means you just toss the seed in the ground, so the workload is minimal. Some preliminary preparation is recommended before you start the spring garden, however.
First, make sure you have some good frost protection on hand when temperatures unexpectedly dip (and they always do). Make cloches from milk cartons (staple a popsicle stick to the carton to stake it into the soil) to cover individual plants and invest in some good frost cloth for larger areas. Avoid using plastic to cover plants, if possible, as it doesn't always provide adequate protection; if you do use plastic cloches, make sure the plant doesn't come in contact with the plastic. Keep a few old sheets or blankets on hand too, and some clothespins or spring clips to secure cloth over plants.
Because so many spring vegetables are root crops (beets, carrots, radishes, etc.), it is essential that the soil in your planting beds be in good shape. Work in lots of loose, crumbly organic material like compost and finely chopped leaves. Root crops like to grow downward with little effort. Planting in hard, rocky soil will result in stunted, tough crops.
As for your seeds, make sure they are fresh...preferably no older than two years from the current season. Also, if you're planning on growing beets and/or spinach, their seeds benefit from an overnight soaking in water to soften the hard seed coat.
Certain vegetable types are better suited for spring growing than for fall, so check your seed packet information. For example, sprouting broccoli - the kind that sends out tons of little sideshoots, not one solid head -- will not perform well in autumn, but goes like gangbusters in late winter/early spring. Conversely, cauliflower can be tricky to grow if your spring temperatures fluctuate wildly. If, however, your climate stays moderately cool, cauliflower should do well for you in the spring.
Many cultivars within specific vegetable types have been bred to perform better in the spring. Some have been hybridized and designated as "early" types, so they mature more quickly, meaning they can be planted earlier since they tolerate cool temperatures well and are therefore less likely to be exposed to the uneven weather conditions of late spring/early summer.
Throughout most of the U.S., spring vegetable seeds can be direct-sowed until around April 1. If you're in a milder climate, don't go beyond March 15 to start your spring veggies; most won't take the oncoming heat.
Here are a few varieties to look for when shopping for spring vegetable seeds. In general, these can be planted early, will mature quickly and can take light frosts. All varieties listed are available from Johnny's Selected Seeds and probably several other seed companies. (The days to maturity column is calculated from seed sowing, not transplants.)
As for lettuce and other leafy greens, it's pretty amazing how tolerant they are of crazy temperatures. As long as the weather doesn't stay overly hot (80 or above) or cold (below freezing) for an extended period, cold-tolerant varieties will do well throughout the spring, especially if you get a good amount of rain in your area.
I can vouch personally for a gorgeous redleaf lettuce variety called ‘Vulcan' -- it has over-wintered beautifully in an exposed bed next to my driveway. I keep it nestled among chopped leaves and cover it with the leaves when cold weather comes around, but it keeps growing and tasting great - even when temperatures drop down into the 20s!
It's a good idea to keep lettuces mulched well anyway, to prevent soil splashing onto the leaves, and to help maintain a consistent soil temperature and moisture level underneath the plant. You can harvest lettuce leaves as soon as they're big enough to eat. In the case of leaf lettuces, simply give the head a "crew cut" and it will, in most cases, grow back.
I didn't address potato and onion planting here because the advice for planting times and techniques differs so wildly, depending on your region. We start both in mid-February here in North Texas and most people would be aghast to read that. Sort of like the "foot-tall tomatoes by mid-March" thing.
If you have questions about spring planting and what varieties are best suited for your area, your local County Cooperative Extension office can lend a hand. Visit http://www.csrees.usda.gov/Extension/ to find an office near you.