fbpx skip to Main Content

Download a printable copy of our May Gardening “To-Do” Checklist.

Perennials and Flower Borders

  • Continue planting perennials and moving your extras to better spots in the garden – just be sure to check if they need water every day for the first week (if it doesn’t rain) and cut back on watering over the next month to once or twice a week (again, if it doesn’t rain).
  • Deadhead spring bulbs as they fade, but don’t remove the foliage – the bulb needs to withdraw energy from the leaves to make new bulbs for next year.
  • Edge your garden beds (if you didn’t do it last month) for a clean, neat look and easier weeding. Here’s how to edge naturally
  • Apply 1-2 inches of mulch (if you haven’t already), and we recommend shredded hardwood.
  • Start pinching your mums (and other tall perennials that bloom in late summer) to produce fuller plants and prevent flopping.
  • Many summer-blooming perennials can be cut back part way now to make them shorter and stronger when they bloom. Read more about this technique in The Well-Tended Perennial Garden: Planting and Pruning Techniques by Tracy DiSabato-Aust.
  • Stay on top of the weeding!


  • Time to buy and plant summer annuals, and start watering and feeding.
  • Time to plant tender bulbs like cannas, elephant ears, dahlias and caladiums.

Trees and Shrubs

  • For maximum blooms next year, remove the faded lilac blooms.
  • Prune away dead, damaged and diseased stems and branches when you notice them.
  • Feed your roses once this month (then again in June and July and once in October).
  • Plant new shrubs and trees, watering well and continuing to water weekly through their first season in your garden, unless it rains (and thunderstorms don’t count!).


  • In early May, do your garden prep if you haven’t already. For most gardens that means adding compost (Leafgro is great), turning it in gently rather than tilling it.
  • Mid-May is the traditional time in our region to plant summer vegetable seedlings.
  • In early May plant woody herbs now – like rosemary and thyme.
  • Seeds and tiny seedlings of fleshy, non-woody herbs like cilantro and basil are good eating for birds, so keep them protected from birds until the plants grow larger.
  • If you haven’t already planted your potatoes, do it now.
  • Time to direct-sow beans in the ground.
  • Beans need really warm soil, so wait until late may to plant them – or in early June, depending on the kind of weather we’ve been having.
  • Weed, weed, weed – they compete too darn well with your desirable edibles. You can just snip off the annual weeds, but perennial weeds really need to be dug up.


  • It’s a big month for mowing – and the good news is if you leave grass clippings on the lawn, they’ll feed your turf (literally, about a third of its yearly requirement of Nitrogen!)
  • Got something to add, or a even correction to suggest?

Help the gardeners of the Metro DC area and leave a comment!

This Post Has 0 Comments

Leave a Reply

Your email address will not be published.

Back To Top