May Gardening Checklist & Tips

May Gardening Checklist & Tips


  • Cool weather crops can be planted early in the month without protection. This includes root crops, leaf crops, and peas.
  • Warm weather crops, including tomatoes, peppers, melons and cucumbers, can be planted early in the month in Insulated plant protectors, or later in the month without.
  • Sweet corn can be seeded in mid May, beans in late May or early June.
  • Add Soil Enhancer or compost as well as sulfur, and rototil into soil to prepare seed bed.
  • Use Garden Inoculant when planting peas and beans for maximum success.
  • Remember tomato cages and trellises for vining flowers and vegetable crops.
  • Place a floating row cover over your crops for quicker growth and to keep insects out.
  • Keep weeds at bay with hand weeding, hand cultivating, or spot spray with Killzall herbicide.


  • May is the best month to plant potted roses. Prepare soil with T&C Soil Enhancer and water in with Fertilome Root Stimulator.
  • Bring rose blossoms indoors by cutting the stem on a 45 degree angle right above the first five-leaflet leaf under the flower. Place in a water-filled vase immediately.
  • Prune off spent flowers in a similar manner. This will encourage more blossoms.
  • Apply Fertilome Rose Food w/Systemic every 6 weeks to feed and protect from insects.
  • Watch for powdery mildew or black spots on leaves and spray with Fertilome Systemic Fungicide at first sign. Make weekly preventive sprays if you’ve had problems in the past.


  • Perennials and hardy annuals such as pansies, petunias, alyssum, and snapdragons can be planted any time now. They will tolerate frost without problem.
  • Tender annuals such as marigolds, impatiens, and geraniums can generally be planted safely after Memorial Day. If planting earlier, keep an eye on the weather and be ready to cover if necessary. Ask for our tip sheet listing the frost hardiness of various annuals.
  • Direct sow wildflower seed as well as annuals such as alyssum, marigolds, and calendula.
  • Now is a good time to plant up your porch pots. Feed with Gardencote slow-release fertilizer.
  • Place plant supports such as grids or cages around tall growing perennials like peonies and delphinium before they get too tall.
  • Mulch beds with Soil Pep to control weeds and help retain moisture.
  • Fertilize annuals and perennials with T&C Fruit & Flower Food or Save-a-Tree.


  • Adjust sprinklers to water more often as weather warms. Don’t water more often than every other day, and probably only twice per week. Early morning is best, if possible.
  • Apply T&C Premium Lawn Food (Step 2) in mid to late May as grass begins to lose its dark green color from the T&C Humates you applied in early April.
  • Apply Hi Yield Grub Free Zone in May to prevent damage from grubs later in the summer.
  • Seed new lawns using T&C Premium Lawn Seed. Apply T&C Seed & Sod Starter at time of planting. Ask for our free Lawn Planting Guide for complete details.
  • Spray lawn weeds with Fertilome Weed Free Zone if temperatures are under 80 degrees.

Trees & Shrubs

  • May is a great time to plant potted trees, vines, and shrubs. Use Fertilome Root Stimulator.
  • Fertilize trees and shrubs with Save-A-Tree or T&C Tree & Shrub Food.
  • Prune Spring flowering shrubs like forsythia and lilac right after they bloom.
  • Apply Fertilome Systemic Insect Drench or Acecap Systemic Implants to prevent insect damage to your trees and shrubs for the entire growing season.
  • Spray spruce trees with Bonide Systemic Insecticide as the new needles emerge to prevent the brown pine-cone-looking galls from developing on the tips of the branches later on.
  • Check for evidence of borers in your aspen, ash, and other trees. Small holes, possibly with leaking sap and/or sawdust are signs of problems. See our Garden Advisors for solutions.
  • Spray evergreen and shade trees with All Seasons Dormant Spray if you find scale


  • Prune and thin raspberry plants to clean up last year’s dead canes.
  • Apply manure and soil sulfur to berry patches if not done last fall.
  • Apply Casoron granules to raspberries before new canes emerge to prevent weeds.
  • Plant bare root or potted raspberries, strawberries, and fruit trees.
  • Spray mature fruit trees with Dormant Spray to kill overwintering insects and eggs.
  • Spray pear and apple trees with Fertilome Fire Blight Spray twice during blossom period.

Birds and Wildlife

  • Keep bird baths clean and filled with water to attract songbirds.
  • Plant shrubs and flowers to attract, feed, and provide cover for birds and hummingbirds.
  • Place hummingbird feeders out now to attract these delightful little birds to your yard
  • Clean your bird houses before the new birds arrive.
  • Continue to feed birds with suet, black oil sunflower, and high quality wild bird seed.


Always read and follow label directions when using any garden chemical or fertilizer.