Beware the ides of March. The average date of last frost is about March 15th. The keyword is average. The actual date varies year to year; 50% of the time before this date and 50% of the time after this date. The percentage drops as the days wear on until you get to the “average” frost free date; about April 5th. Adjust for your own microclimate. A few miles in distance, a few feet in elevation, the proximity of a large body of water, are some of the things that can have a marked influence on temperature. As a gardener, you will come to know your own climate intimately, especially if you keep a garden journal or other record.
March is getting too late into the season to direct seed crops like Swiss Chard, Spinach, Broccoli, Cabbage, Collards, Kale, Mustard, Seed Potatoes, Snow peas, Turnips, Onions, and Garlic. These vegetables are better planted in the early fall and grown in cool weather.
So, what can you direct seed now, and especially toward the end of March? Try Arugula, Basil, Beans, Carrots (all month), Corn, Cucumbers, Squash, Melons, Lettuce (“starts,” direct seed, and transplant), and Southern peas.
Transplant “starts” into the garden: Tomatoes, Lettuce, Squash, Peppers, Melons, Cucumbers, Eggplant, and Basil. If you have started your own plants, your have saved yourself some coins. If not, you will find a good selection at your local nursery for a fair price.
A word of advice, be prepared to protect newly planted vegetables from a late frost or freeze. Planting later in March or even in early April may be safer. The other side of that coin is that the earlier the planting, the better the chance of beating the warm weather onslaught of diseases and pests. And if you have the space to do it, rotate your crops season to season in different parts of your garden plot. This also helps control pests and disease.
Tomatoes are somewhat of an exception to other members of their plant family, like peppers and eggplant, in that they can tolerate the cooler weather in March better. So, you can get them it ground earlier in March.
Wait until your plants have grown some before apply mulch; late April may be a better time. Compost is a good idea any time. Its dark color will absorb the sun’s warmth.
Again, since here is a good chance that we will have one or two more nights with freezing temperatures before April. Be prepared to protect your early plantings. Spun bonded reemay row cover may be all you need. It raises temperatures underneath by about four degrees F. It can be left on the rows all winter. While it blocks only 15% to 20% of the sun’s rays, plants will benefit from the slightly warmer temperature that spun bonded row cover provides. I’ve even seen it wrapper around small citrus trees for protection. That’s usually enough to prevent freeze damage.
Small individual plants like early planted tomatoes can be covered with unused plant pots or milk jugs with the bottoms cut out. Be sure they are removed before the sun shines on them the next morning; lest they be fried.