The last frost date -- 5-5-14

(This week’s flower is the dog violet, Viola labradorica. To enlarge the picture, please click on it.)

In Western Maryland, May 3 is the “last frost” date, according to a chart available through the University of Maryland Extension’s Home and Garden Information Center. Years ago, local extension agents listed it as May 15, which seemed like a safer choice for plants like tomatoes, which wilt when “frosted.”

Certainly vegetable gardeners have planted their “cole crops” by now. They can stand some cold weather, though I’d cover them if a hard freeze is forecast. Planting tomatoes and peppers now means they will probably just sit there in cool soil and not grow too much. And if you’re growing melons from transplants, cold soil might be a killer. For those, wait until late May or early June.

But holding off on planting tomatoes, peppers and melons doesn’t mean you must stand on the sidelines for the next few weeks. There’s plenty that can be done now. There are several things you can do to increase your chances of success, including:

-- “hardening off” your transplants, which means gradually letting them get used to cooler weather than they’ve had on your windowsill, or under your “grow lights.” A week or 10 days before transplant, set out the plants in a sunny area sheltered from the wind. Up against a brick wall is perfect, because the bricks -- assuming they haven’t been painted white -- will absorb heat and reflect it onto the plants. Bring them inside when the temperature begins to drop. And begin to reduce the amount of water you give them.

-- Pick a cloudy day if possible to plant, so plants raised on a windowsill don’t get sunburned because the light there wasn’t that bright.

-- if tomato plants are leggy, plant them with part of the stem in a small trench alongside the plant. They will grow additional roots and are less likely to be blown over by the wind.

-- stake tomatoes when you plant them. Letting tomatoes ramble in the garden is an invitation to insect pests and groundhogs. Peppers need not be staked at first, although a heavy yield might require it later.

-- Pile dead leaves and/or grass clippings around the plants, to keep the soil from drying out too quickly. Both should be dry, to prevent formation of an impervious surface that will block water.

-- To prevent tomato damage by cutworms, fold a small piece of foil around the stem at ground level.

-- To prevent damage to “cole crop” transplants, get some clean cardboard -- without slick, colored surfaces -- and create “root maggot mats” of 10 inches to a foot square for each plant. The root maggot is the larvae of a fly that lays its eggs at the base of these plants. If the larvae must crawl across the cardboard to reach the soil before it begins to burrow, many of them won’t make it. You can also use floating row covers to keep the flies out.

-- starter fertilizer -- I’d say 5-15-5 is a good mixture -- will help plant vigor. Use the liquid form if possible, because it’s more easily absorbed.

-- if frost does threaten after all those precautions, cover each tomato with a plastic milk jug with the bottom cut out and the top left off. Remove the next day, after the temperature rises.

-- mulch will keep down the weeds and prevent evaporation of water, but if you choose black plastic mulch, lay out the row as a shallow trench, so that rainwater runs into the plant holes and reaches the plant.

-- in the past I’ve used “trickle” irrigation systems that use small emitters at the base of each plant to drip out a gallon in an hour’s time. If that seems like too much trouble, get some of those milk jugs, tie them to the tomato stake and poke a small hole or two in the bottom, close to the stalk. Then fill each with a gallon of water and your watering is done. If you water with a hose, you’ll get a lot of water on the space between the rows and encourage the growth of weeds.


The University of Maryland Extension’s Home and Garden Information Center is running a contest for small-plot gardeners called the Grow 100 challenge. The idea is to grow the best garden you can in 100 square feet. The gardening space can be two or more plots, but the total growing space must not exceed 100 square feet. The prizes are relatively small -- $25 and $50 -- but the idea is to share what you do, tell what worked and what didn’t and have a good time. For more, visit

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