Coastal Region – Glen Payne
- Irrigation settings: System audits should be completed this month. Broken heads & sprays repaired; missing drip emitters installed. Nozzles & spray heads adjusted. Broken or leaking lines repaired.
- Verify that rain sensors are working correctly, controlling the system and turning it “On & Off” as advertised. Repair wires, insert new disks, and check the rain depth setting.
- Application of slow-release fertilizer (12-6-6 or 16-4-8) to trees & shrubs should be completed by the end of the month to support new growth.
- Scout plants for small insects that may be feasting on new plant growth. As temperatures heat up, be sure to inspect the undersides of leaves for insects, where they will seek shade and protection. Hiding under plant leaves also prevents them from being easily seen and eaten by other animals & beneficial insects.
- Be on the lookout for the Yellow Legged Hornet that has been making appearances in the South Carolina Lowcountry and report them.
- Inspect plants, especially evergreens, for spider mites, as the temperatures have been high and dry lately. Two-spotted spider mites have been starting out on the undersides of leaves and moving through shrubs as populations build.
- Native plants continue to attract pollinators at this time of year, require minimum maintenance and currently available at local Native Plant sales around the county. There are over 20 types of Baptisia (False or Wild Indigo), all native to the eastern United States. Several are native to the Southeast.
Midlands Region- Carmen Ketron
- It is another year of sub-optimal rainfall to start the growing season. If the drought conditions continue, supplement plants and grass with water as needed.
- Turfgrass needs approximately 1 inch of rain each week during the growing season. When irrigating the lawn, do it early in the morning, once or twice a week, to equal one inch total.
- Newly planted vegetables and flowers will need consistent watering to provide one to three inches of water each week. Remember, their root systems are not as well established, so more frequent watering is necessary to become established. Mulching around plants can help to retain moisture in the soil after watering.
- Established perennial shrubs and trees with established root systems will be more resilient in the face of drought but will benefit in the long run with 1-3 inches of water per week.
- Keep an eye out for warm-season weeds emerging in lawns. Identify the weeds and hand remove them early to prevent them from re-seeding or outcompeting desired plants.
- Scout plants and turfgrass for insect infestations often and consistently. Specifically, look out for Japanese beetles and scale insects on plants, chinch bugs, and mole crickets in lawns.
- Direct seed heat-loving vegetables, including okra, pole beans, and southern peas.
- Now is the time to purchase and plant sweet potato slips until June 15th.
- If some garden areas are going to be left empty for the warm season, sow summer cover crops in garden plots and raised beds to promote soil fertility, reduce weed growth, and reduce disease and pest pressure.
- Begin planting summer and fall flowering bulbs like dahlias, gladiolus, and canna lilies.
Upstate Region- Ginger Long
- Much of the Upstate region is abnormally dry, with some areas still experiencing moderate drought. Go to the US Drought Monitor site to see the status of your county. Pay close attention to the water needs of plants that have been recently planted. Set irrigation schedules so the lawn is deeply watered once a week.
- Early May is the recommended time to fertilize lawns throughout the state. Follow the recommendations from your soil report on the type and amount of fertilizer to apply. If you have not yet had a soil test, consider doing so this month. Instructions on how to collect samples are in our factsheet, HGIC 1652, Soil Testing. Take samples to your county Extension office for testing by the Clemson Agricultural Service Laboratory.
- The first two weeks of May are the optimum time for seeding warm-season lawns. The soil temperature is warm enough, and the air temperature is not so hot that seedlings will suffer.
- Post-emergent herbicides can be applied now that the spring green-up period is complete. Apply them when air temperatures are below 85 degrees. Higher temperatures can cause turf damage.
- Prune spring-flowering shrubs soon after they flower, including azaleas, forsythia, deutzia, spiraea, etc. They will produce new flowers for next year this summer, so prune by the end of May.
- Plant summer-flowering bulbs like caladiums, elephant ears, gladioli, dahlias, cannas, lilies, and many more now that the danger of frost has passed and soil temperatures have warmed.
- Water the vegetable garden consistently. This helps prevent blossom end rot on tomatoes.
- Okra, sweet potatoes, and sweet corn can be planted in May. Visit the Planning a Garden factsheet for more planting dates.
- Succession planting can prolong your flower show. Plant small numbers of seeds every few weeks so that new plants are sprouting as the older plants start producing flowers. Flowers to plant in succession include sunflowers, cosmos, and zinnias for color throughout the summer and into fall.
- Move houseplants outdoors in May. Place them in the shade for several days to acclimate. Leaves may burn if placed in direct sunlight too soon after being moved outside.
If this document didn’t answer your questions, please contact HGIC at hgic@clemson.edu or 1-888-656-9988.
Author(s)
Glen Payne, Urban Horticulture Agent, Beaufort County, Clemson Extension
Carmen Ketron, Urban Horticulture Agent, Darlington County & Florence Master Gardener Coordinator, Cooperative Extension, Clemson University
Ginger Elizabeth Long, HGIC Agent, Home & Garden Info Center, Clemson Extension, Clemson University
Tradescantia virginiana, Spiderwort
During drought, raised beds and planters will need supplemental watering more often. It may also be beneficial to pivot to liquid fertilizer instead of a granular fertilizer to make it more accessible to plant roots.
Caladiums (Caladium spp.) may rot if planted too early. Wait to plant them until May so they get enough heat.
