This Month in Your Garden- May 2024

Coastal Region – Brad Fowler

  • The time to fertilize warm-season turfgrass has finally arrived. Be sure to fertilize based on soil test results and the specific needs of the turf. Check out the yearly maintenance calendars for each type of turfgrass for more information.
  • As daytime temperatures start to rise, monitor turf for drought stress but only water as needed. Practicing conservative irrigation can help build stronger roots.
  • Keep an eye out for turf diseases like large patch. Large patch can become very active this time of year due to warmer temperatures and higher humidity.
  • Selective herbicides to control weeds in lawns can be applied in May, but be sure to read and follow all label instructions. Herbicides applied incorrectly can be a safety concern and cause damage to the lawn.
  • Make sure to prune shrubs like Azalea and Bigleaf Hydrangea after they are done blooming. Shrubs that produce flowers in the spring do so on growth from the previous season.  These plants need time for new growth to mature before producing flowers the following spring.  Not all shrubs need to be pruned at the same time, so research pruning times for each specific plant.
  • Treating fire ants with a dedicated bait now and in the fall can help reduce populations significantly.
  • Plant okra, beans, cucumber, and other warm-season vegetables.
  • May is a great time to add some warm-season annuals to the landscape for a splash of color throughout the summer.
  • Native azaleas blooming in the spring. Brad Fowler, ©2024, Clemson Extension
    Native azaleas blooming in the spring.
    Brad Fowler, ©2024, Clemson Extension

Midlands Region – Jennifer Weaver

  • Get started scouting to properly control pests and diseases in the garden.
    • Implement preventative cultural practices such as proper mulching practices to reduce plant stress and keep your plants as healthy as possible.
    • Practice close observation once or twice a week to quickly address any issues that you notice.
    • Check the interior of the plants and underside of leaves for insect pests.
    • Be able to identify beneficial insects or common predatory insects. Use a hand lens or phone camera for close-ups to correctly identify pests before any action is taken.
  • Hand pull winter annual weeds (henbit, Carolina geranium and chickweed) from landscape beds before they set seed.
  • Continue to plant trees, ornamentals and perennials, but plan to water regularly to aid in their establishment before hot summer weather arrives.
    • Keep slightly moist, not soaked, until established. Established means they are able to survive on their own without additional water.
    • Even drying out for one day can cause significant root death.
    • If watered properly, plants establish quickly and are more resistant to drought, disease and pests.
  • Choose summer flowering bulbs now!
    • Summer-flowering bulbs are planted in spring after the danger of frost has passed.
    • They include hardy to tender bulbs that flower in summer, with a few that flower until frost, such as Dahlia
    • These include true bulbs, rhizomes (Canna species), corms (Gladiolus species), and tuberous roots (Dahlia species). We commonly call “bulbs” any plant that grows from fleshy underground storage organs.
    • Hardy bulbs can over-winter in the ground: Agapanthus (Lily of the Nile), alliums, Belladonna lily (Amaryllis belladonna), American or Oriental hybrid lilies (Lilium), crocosmia.
    • Tender bulbs are either dug after the first frost or the containers are brought indoors. Examples are gladiolus and caladiums. They are dried or placed in storage material, in a cool place and can be replanted in the spring after the fear of frost has passed. If in a container, it can be moved back outside.
    • Avoid bulbs that are soft, molded or discolored. Instead, choose bulbs that are firm with unblemished skin.
    • A general rule of thumb for planting – two to three times the greatest diameter of the bulb. Most prefer a well-drained, loamy soil. Good drainage is essential.
    • Plant the bulbs and press the soil firmly around them, then water thoroughly to settle the soil.
  • Bearded iris and daffodils – after blooming, cut off spent flowers and stalks. Remember to allow daffodil foliage to wither and die down naturally before removing it.
  • Pruning Shrubs
    • Spring flowering shrubs (those that bloom before June)
      • Prune after flowering – their flower buds develop during the previous season (set flowers on “old wood”). Examples are azaleas, forsythis, fothergilla, and weigela.
    • Summer flowering shrubs
      • Prune in late winter/early spring because their flower buds are formed on “new wood” produced during the current season. Examples are abelia and clethra.
    • Hydrangea species vary in the type of wood they bloom on, so make sure to know the category type of your hydrangea.
      • Bigleaf hydrangeas (Hydrangea macrophylla, which includes lacecap hydrangea) set flower buds on old wood, so prune immediately after flowering.
      • Oakleaf hydrangea (Hydrangea quercifolia) – blooms on old wood. If needed, prune as soon as the flowers have faded unless you want to enjoy them as they fade from white to pink.
      • Panicle (Hydrangea paniculata) and smooth hydrangeas (Hydrangea arborescens) also bloom on new wood produced during the current season and can be pruned in late winter or early spring.
  • Check out this video from Dr. Eric Benson, Clemson Extension Urban Entomologist, to learn more about the periodic Cicada emergence from Brood XIX in mid-April to mid-May 2024.
    • Gladiolus are often grown as cut flowers and are available in a wide array of colors.
      Gladiolus are often grown as cut flowers and are available in a wide array of colors. Millie Davenport, HGIC 2018 HGIC, Clemson Extension

Upstate Region- Millie Davenport

  • I am super excited that the month of May has arrived. There is so much to do that deciding what to do first can be hard. I decided to start by selecting a small spot near the entrance of my house to add pops of annual color. The brightly colored flowers will bring me joy and will also be a way to add instant gratification to my efforts. I usually plant geraniums, calibrachoa, and cuphea near my door. The color makes me happy, while the cuphea attracts the hummingbirds.
  • Add summer flowering bulbs like gladiolus, dahlias, and caladiums to the landscape.
  • Moving on to the vegetable garden. Finish planting warm-season vegetables like tomatoes, peppers, sweet corn, squash, and cucumbers. But hold off on sowing those heat-loving vegetables, like okra and southern peas (crowder peas), until later this month. Also, consider adding sweetpotato slips to the garden this year.
  • Maintain a 2- to 3-inch layer of mulch in the landscape beds. Mulch has many benefits (reducing weeds, retaining soil moisture, and keeping soil cool). In addition, choosing an organic mulch material, such as shredded hardwood or pine needles, will benefit this soil as it breaks down over time.
  • If needed, spring flowering shrubs like azaleas can be pruned by using a thinning cut to remove a third of the tallest branches. This will open up the plant to receive more light to penetrate the center of the shrub and encourage new growth.
  • When mowing the warm-season lawn, remember to remove just a third of the leaf blade at a time. Warm-season lawns can also be fertilized now that they have fully greened up.
  • Lastly, remember to have fun and enjoy the growing season that is upon us.
  • Dahlia 'Catlin's Joy' has a ball flower form with shades of bright violet and apricot. Millie Davenport, ©2024 HGIC, Clemson University
    Dahlia 'Catlin's Joy' has a ball flower form with shades of bright violet and apricot.
    Millie Davenport, ©2024 HGIC, Clemson University

If this document didn’t answer your questions, please contact HGIC at or 1-888-656-9988.

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