APRIL 2021
  In spite of the temptation, don’t plant annuals in your flowerbeds just yet.  You need to wait until the danger of frost is past—usually mid-May along the Front Range.  There are only a few hardy flowers, such as pansies and violas, that can safely be planted now.
Once crocuses, daffodils, tulips, and other bulbs have bloomed, cut off faded flowers, but do not trim off the leaves until they have wilted and died.  The leaves produce food that the bulb will store and use for next year’s growth and bloom.
  Purchase summer-flowering bulbs in early spring while the selection is good, but wait to plant them after the danger of frost is past.  Local garden centers, gardening sites on the web and flower catalogs offer a wide selection of bulbs such as amaryllis, dahlias, gladiolus, lilies and tuberous begonias.
You still have time to plant bare-root roses early this month.  This is also a good time to transplant roses.  Be sure to provide them with plenty of water.  Container grown roses are usually planted in May.
Wait until the end of the month to prune roses.  New growth can be badly damaged by killing frosts if you prune them too early.  
During April you can plant cold hardy vegetables:  peas, carrots, broccoli, cauliflower, radishes, potatoes, spinach, turnips, cabbage and lettuce.
  Don't prune spring-flowering shrubs, such as lilacs, at this time.  They should be pruned right after they have bloomed.
  You should remove the tree wrap you placed on the trunks of young trees last fall.  It can constrict the growth of the tree trunk and foster insects and disease if left on during the warmer months.
If you didn’t fertilize your lawn in the fall or mid-March, then you might want to fertilize it with a good nitrogen fertilizer in early April to promote spring green-up and growth.  (This recommendation does not apply to Buffalo grass or Bermuda grass.) 
  To prevent problems with crabgrass and other grassy weeds in your lawn you may want to apply a pre-emergent herbicide in early April.  (Note:  A thick, healthy lawn that is maintained properly will help prevent the growth of weeds, enabling you to limit the use of chemicals.)
  Spring is a good time for core aerating your Kentucky bluegrass lawn.  This procedure helps control thatch build-up and reduces soil compaction and water run-off.