When we look at our average frost-free date, we see that it is
April 25. About half the time in the last 30 years, the average
last spring killing frost has occurred by that date. This also
means that about half the time it hasn't. The first week of May
commonly sees a killing frost. Many annual flowers, tomato
plants and other warm-season plants should not be set out until
after May 10.
Those selling transplants love those of us who
like to buy these plants in early to mid-April. More years than
not, they get to sell us at least two sets of transplants. Of
course, all bets are off if you use protective covers -- such as
milk jugs, row covers or wall-of-water types of protection.
Usually it is just as easy to wait until the recommended date,
and that would be after the range of April 25-May 10 for green
beans, sweet corn and tomatoes. These are all considered "tender
There is still time to start a few of your own transplants,
and this is especially true if you are willing to wait an extra
week to set them out. You can also set them out at a smaller
size with the protective covers mentioned above. Eggplant,
herbs, pepper and tomato would be started about March 25.
Cucumber, muskmelon and watermelon are started as early as April
15. The rule of thumb is to allow about six weeks before you
want to set the plants outside.
Melons, peppers, pumpkin and squash are considered
"warm-loving" and should be planted in the range of May 10- June
1. Pumpkins planted for Halloween jack-o'-lanterns should be
planted about Father's Day. These pumpkins will get ripe too
quickly for use in late October if planted at the normal time.
Pumpkins for pies can be planted in the May 10-June 1 period.
Any time now, when soil conditions permit, it is time to
plant things such as asparagus crowns, leaf lettuce, onions,
peas, potatoes, radishes, rhubarb plants, spinach and turnips.
Give it another week or two and it is time to plant such things
as broccoli, cabbage and cauliflower. As with most things, a
little bit of planning goes a long way in preventing problems
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Questions abound regarding fertilizing the garden. The rule-of-thumb
rate (without soil test information) for fertilizing flower or
vegetable gardens is about 15 pounds of 10-10-10 per 1,000 square
feet of area. If you are using 12-12-12 or 13-13-13 fertilizer, use
about 12 pounds per 1,000 square feet.
Soil pH may need to be adjusted due to the addition of lime and
sulfur, which are acidifying. Generally, about 4.25 pounds of lime
neutralizes the acidity from 1 pound of nitrogen or sulfur. Beware
of pH requirements for different plants before you go out to apply
lime. Surrounding plants are also affected. Examples would be
blueberries, rhododendron, azalea, pin oaks and many evergreens.
If you haven't
applied crabgrass preventer, you have a very short window. It
should be on about the time the forsythia blooms, but don't
apply if you seeded your lawn. You can use a post-emergent
product if germination occurred and immature crabgrass is
When it's time to
mow, remove no more than one-third of the leaf blade at a time
to prevent raking or catching clippings.
Cut back butterfly
bushes to live material, with a 10-inch maximum height.
Cut back mums, but
leave 2 inches of dead material since much stored food is
Cut back ornamental grasses to a height
of 4 inches or so.
University of Illinois Extension]