Horticulture Tips for May

Home Grown  by Keith Reed
Consider the following tips for your May landscape:
  • The recent rains have been so welcome! Keep in mind that even with rain, our cool weather this spring (it looks like April will do down in the record book as being cooler than March) has kept the soil temperatures below what we typically expect. In other words, don’t be surprised if some of your plants are not growing much yet. Avoid the temptation to jump start them with additional fertilizer right now.
  • The best time to prune most spring flowering shrubs is shortly after they have dropped their blooms. These plants flower from buds set last year, so pruning now (as needed to control growth or improve shape) insures that the plant has plenty of time to re-grow and set buds fully for the following year. The forsythia is a great example of this principal. These landscape standbys can tend to get large and unruly late in the summer and we tend to want to prune them back at that time. The plant tolerates this just fine but it will not bloom the following spring.
  • Early to mid May should be the last time your tall fescue or other cool season lawn is fertilized until fall. Summer fertilization will only exacerbate disease and heat stress issues these grasses will soon face. On the other hand, now is the perfect time to make your first fertilizer application on your warm season turfgrasses such as bermuda and zoysia.
  • With our recent rains, you can expect to see fungal diseases becoming an issue. If you are spraying fruit trees, remain diligent in the timing of your applications during this period.
  • If you are considering planting new roses, proceed with caution as increasing reports of Rose Rosette disease continue in our area. If you are already growing roses, don’t panic, but it would be a good idea to look at OSU Fact Sheet #EPP-EPP-7329 Rose Rosette Disease (PDF/Mobile). This document provides some very helpful information on managing the disease and well as limiting its spread.

For more information on this or any other horticultural topic, you can contact Keith Reed, the Horticulturist in the Payne County Extension office. Keith can be reached via email at
keith.reed@okstate.edu, phone at 405-747-8320, or in person at the Payne County Extension office, located at 315 W. 6th in Stillwater.

Oklahoma State University, in compliance with Title VI and VII of the Civil Rights Act of 1964, Executive Order 11246 as amended, Title IX of the Education Amendments of 1972, Americans with Disabilities Act of 1990, and other federal laws and regulations, does not discriminate on the basis of race, color, national origin, gender, age, religion, disability, or status as a veteran in any of its policies
Article Archives