Xtremehorticulture

When to Fertilize Lawns

Q. When is it time to
start fertilizing lawns again?

Lawns can be beautiful but they need regular feeding. The light green color of this lawn is an indicator it needs an application of nitrogen fertilizer. That nitrogen fertilizer will turn that light green lawn into a dark green lawn in a matter of a couple days.

A. It depends on whether
the lawn is fescue, only Bermudagrass or Bermudagrass overseeded in Fall to
maintain green winter color. Fescue lawns and overseeded Bermudagrass lawns are
fertilized the same during winter months.

Ammonium sulfate fertilizer contains only nitrogen that the plants need when their color is not dark enough. The sulfur in the sulfate is also important for plants but in the case of light green color, all that’s lacking is nitrogen.3 to 5 pounds of this fertilizer spread evenly over 1000 ft.² of lawn and watered in will turn the color a deep green instead of light green.

            Fescue and overseeded Bermudagrass should have been
fertilized last Thanksgiving to maintain dark green color through winter. If
this fertilizer application was missed and temperatures get cold, the lawn can
turn brown when it gets very cold or just light green if it does not.
            The next fertilizer application to fescue lawns would be
when air temperatures enter the 60s. Fertilize Bermudagrass that was not
overseeded when temperatures enter the 80s.

Once or twice a year add a better quality fertilizer to the lawn like this one. It has a little bit of phosphorus, the middle number. Lawns don’t need a lot of phosphorus because we don’t grow them for their flowers and fruit. I would like to see the potassium, the last number, higher than this but this is a good lawn fertilizer.

            Established lawns require fertilizers containing high
nitrogen, and occasionally an application of iron, for dark green color.
However, they will perform best if this fertilizer contains also low levels of
phosphorus and moderate to high levels of potassium.
            For this reason, fertilizers similar to 21-7-14 or
10-5-10 are frequently recommended for lawns. Some people use only high
nitrogen fertilizer such as 21-0-0 and omit phosphorus and potassium.
            I think this is a mistake and a good lawn fertilizer
should be applied at least once during the growing season. Instead, experiment
and try fertilizing with only half the amount of fertilizer recommended on the
bag. This is all that is usually needed if you are not bagging lawn clippings
but mulching them back into the lawn using the mower.

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