MAY 2022 
  You can plant tender annuals, perennials, herbs and summer-flowering bulbs once the danger of frost is past—around Mother’s Day along the Front Range.  Be sure to harden off young plants prior to planting them outdoors.
  Begin deadheading (pinching or cutting off dead flowers) once annual and perennial flowers bloom.  This improves the appearance of plants and promotes continued bloom.  Cut back the foliage of spring-blooming bulbs only after it has died. 
Roses can safely be pruned in early May except at the coldest elevations.  Cut off all dead and weak canes.  Remove canes that cross or rub against others.  Prune the remaining canes back to healthy tissue—usually to a length of 6 to12 inches.  The cut should be made at an angle about 1/4 inch above an outward pointing bud eye.  (A bud eye is a green nodule that produces new leafy growth).
  When you purchase plants for your containers, don't limit yourself to buying only annuals.  Herbs, ornamental grasses, summer-blooming bulbs and perennials can also go into containers.  The foliage and fragrance of many herbs make them great additions to container gardens. 
  Plant tomato plants when the danger of frost is past and the soil has warmed up.  Be sure to harden off tomato bedding plants prior to planting.  Popular varieties for Colorado gardens include 'Big Beef', 'Celebrity', 'Early Girl' and 'Medina'.  For an explanation of "determinate", "indeterminate" and "V/F/T/N", please see Tomato Terminology in our Tips page.
  Fertilize lawns with a nitrogen fertilizer during May to mid-June.  For tall fescue, Buffalo grass, and Bermuda grass use 1/2 to 1 pound of nitrogen per 1000 square feet of lawn.  Use one pound of nitrogen per 1000 square feet for Kentucky bluegrass.
Sow warm-season grass, such as Buffalo grass, in May or June.  You may also sow cool-season lawns in spring, although the preferred time is late summer or early fall. 
  Don’t assume that your sprinkler system or drip system is working properly in spring just because it was fine last autumn when it was shut down for the winter.  You should check to be sure all the sprinkler heads and drip emitters are functioning correctly.
  By mid-May be on the alert for garden pests.  Early detection often provides an opportunity to manage pests with interventions that do not have a negative impact on the environment and beneficial insects. 
Preventive spraying for Mountain Pine Beetle (MPB) should be done between May 1 and July 15 in areas where the risk of beetles is high.  For additional information contact the nearest office of the Colorado State Forest Service, the U. S. Forest Service, or Colorado State University Extension Service.