May Garden Tips

Birds and Wildlife

  • Lower the purple martin house to clean it out.
  • Change hummingbird-feeder sugar water every week.


  • Get begonias and impatiens in.  Wait until mid-month to plant periwinkles.  Do not water overhead.  
  • Mandevilla, bougainvillea and Chinese hibiscus are great patio plants.
  • Deadhead spent flowers. 
  • Hot weather plants: firebush, lantana, poinciana, Esperanza, firespike, caladium, coleus, begonia, moss rose, hibiscus, bougainvillea, purslane, cannas and blue princess verbena.  
  • Fertilizing potted plants with water- soluble product brings rich color.  
  • Fertilize roses for continued blooming.
  • Let wildflowers go to seed before mowing.  
  • Flower seeds to be sown directly in the soil include amaranthus, celosia, morning glory, sunflowers and zinnias. 
  • Plant hibiscus, bougainvillea or mandevilla vines in containers.

Shade Trees and Shrubs

  • DO NOT prune oak trees.
  • If red-tipped photinia leaves have black spots, remove leaves and throw them in the trash.  
  • Be careful with string-trimmers around young trees.  
  • Spray summer-weight oil to control scale bugs on euonymous.  
  • If red-tip photinias require constant pruning, replace with holly, nandina, xylosma, eleagnus, or pyracantha.

Fruits and Nuts

  • There is still time to thin late-season peaches, apples and plums.  Thin to one fruit per 6-8 inches of stem.  
  • Fertilize pecan trees in early April with 21-0-0 (1 lb. per inch of trunk diameter) to encourage good nut production. 


  • Control army worms and web worms with Bt, Spinosad, or Malathion.
  • Hold bluebonnet seeds in the fridge until September.  
  • Plant Firebush for sun and firespike for shade.  Hibiscus, cigar plant, dwarf Chinese trumpet creeper, lantana, and firebush on the patio.   
  • Caladium corms can be planted now. Wait until temperatures are above 70 F.   

Turf Grass

  • Don’t bag lawn clippings.  
  • May is the month to fertilize buffalo grass but only every 2 years.
  • If starting a new Bermuda grass lawn, use 2-3 lbs. of seed per 1,000 sq. ft. and water twice a day.  
  • St. Augustine grass will fill in drought-killed areas if watered regularly.  
  • There’s still time to fertilize grass.  
  • Yellowing grass leaves with darker green veins signal symptoms of iron deficiency. 


  • Fruit set is sensitive to high temperatures; plant okra, Southern peas, peanuts, sweet corn, watermelons, cucumbers, squash, cantaloupes and eggplant the first part of May.  
  • Pick tomatoes when they change from green to green-white color. 
  • Keep the tomatoes well-watered and mulched to avoid blossom-end rot.  Avoid watering the leaves.
  • Side dress vegetables with 1 cup slow-release lawn fertilizer (2 cups of organic fertilizer) per 10 feet of row every 4-6 weeks. 
  • Harvest, harvest, harvest.  If not, production will slow or stop.  
  • Onions are ready to harvest when the green tops fall over. 

Seasonal Gardening Checklist Prepared by Tom Harris, Ph.D., Honorary BCMG