Gardening Notes For May

Although March and early April were warm and dry, May looks to be a little cooler and moister.  Although a bit chilly for those looking forward to those 90 degree summer days, the cool weather will allow spring blooms to last and to be enjoyed to their fullest!  May is always a hectic month, so take the time to make notes in your journal and take long evening strolls to smell the fruits of your efforts. 

Things to do:

  • Prune leggy Azaleas and Rhododendrons as they finish blooming.  This will improve the habit yet still ensure proper flower bud development for next year.
  • By late May it will be clearly evident which parts of a plant – if not the whole plant – has died back from winters chill and should be removed.
  • If you have fertile soils, some perennials such as Asters and Sedums should be pinched in mid to late May to prevent them from flopping later in the season.  
  • Let bulb foliage turn yellow or light brown before removing to ensure proper bulb and flower development for next year.  Do not tie it together, since that reduces that amount of surface area exposed to the sun and its ability to make sugars.
  • For bulbs such as Eranthis (Winter Aconite), gather the seed capsules as they begin to ripen and spread the seed throughout woodland areas.  Longwood Gardens has found this a far more successful method of spreading the plants about than the typical method of installing the tubers in the fall.
  • For a neat garden, edge those bedlines!  For vegetable and annual gardens, turn under any manure or green crops that was spread or seeded out last fall.  Make certain the soil has drained properly before tilling.
  • Plant out tender annuals after the last frost-free date in your part of the state (generally May 15 but it may be later this year).  May temperatures can fluctuate from 90° one day to 30° the next!  Also, certain annuals that like it warm, such as Catharanthus (the annual Vinca) or Sweet Potato Vines should not be planted until late May or early June.
  • Remove the Banana and Cana roots from the basement and plant them in a sunny location in soils that are enriched with compost to help hold moisture.
  • Thin those cool season vegetables that were directly sown during April so that they will develop more fully.
  • Start to plant frost tender vegetables.  For the eager, the wall of water can be used for tomatoes and other tender vegetables that are planted during the potentially cold first half of the month, although there is no harm in waiting until early June!
  • Cut those lawns.  Remember, 2 ½ - 3” length is far healthier for the turf than a 2” cut.  Do not remove the clippings since they release nitrogen back into the soil as they break down.
  • Spot treat for dandelions or any other aggressive lawn weed.
  • Finish mulching perennial or shrub borders during the early part of May and start to weed!  Remember the average weed seed’s life is 7 years, so remove those weeds before they go to seed.
  • Frequently visit local garden centers as new additions are coming in weekly.
  • Plant sales at botanic garden occur throughout the state and are a great source for finding unique or hard to find plants – plus it supports the various gardens.  The sale at Rutgers Gardens is May 6-8 in 2016, with plants available at the Farm Market ever Friday from 11:00-5:00 and weekends at the Gift Shop!! 
  • Read the notes that you made this winter and last May and reflect on how to improve the garden.  It is now time to put your thoughts into action!