The Spring Garden
Fertilizer, Weed Prevention and More
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[March 31, 2008]
While 60-70-degree temperatures get us used to
spring and summer, we may be jumping the gun on planting warm-season
garden items. Many annual flowers, tomato plants and other
warm-season plants should not be set out until after May 10. 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 this date. That also means that about
half the time it hasn't. The last two years have been good examples
of a late-season freeze occurring.
Those selling transplants love those of us who like to buy these
plants in 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 vegetables."
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.
We are getting quite a few questions about fertilizing a
garden. The normal 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.
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One of the more popular questions, at least during the growing
season, concerns how to prevent the leathery rot on the bottom of
tomatoes. The leathery rot is called blossom end rot. It is caused
by a calcium imbalance in the plant. You could apply some lime to
the area where tomatoes will be planted, because lime supplies
calcium. The more reliable method is to mulch tomato plants well.
This evens out the soil moisture available to the plants. The
alternative is watering on a frequent basis, but too much water can
cause root rot problems.
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 later on.
It is time to get
the crabgrass preventer on, but don't apply if you seeded your
It is about time to
mow already, and 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, Logan County]