September Gardening Activities

​by Cathy Bylinowski, MU Extension Horticulture Instructor  

     Perhaps you are still picking vegetables and admiring attractive zinnias or Rose of Sharon bushes this September.  Soon it will be time to harvest sweet potatoes and the last tomatoes!
     September is also prime lawn care month. If you have areas where turf grass has died, now is the time to prepare the soil and reseed. This MU Extension Publication that will give you detailed information about how to do it- Cool Season Grasses: Establishment and Renovation- https://extension.missouri.edu/publications/g6700
     Here are some tips from the Missouri Environment and Garden online Newsletter:
 
Tall fescue and/or Kentucky bluegrass- Cool Season lawn grasses
     September is the most important time to get to work on your lawn and rebuild turfgrass density after a long, difficult summer.
     This is the most important time to fertilize cool-season lawns. Apply fertilizer at a rate of 1 lb. nitrogen (N)/1000 sq ft. Potassium (K) may also be a component of the fertilizer at a 1/3 to 1/2 rate of the nitrogen, particularly if the soil test indicates a deficiency. Do not apply phosphorous (P) unless a soil test indicates it is needed since some soils are already at high or potentially toxic levels and established turfgrass is good at getting to even lower concentrations.
     Mid-September is also a great time to seed or overseed a lawn. If a lawn is less than 50% desirable turfgrass then consider a complete renovation, but in most cases a good overseeding will help rebuild density. Aerate or verticut if possible, then fertilize, (aerate or verticut again if possible), seed and lightly rake in. If the soil is low in phosphorous, addition of this nutrient may be necessary when seeding.
     Overseeding rates for tall fescue and a tall fescue/KBG mixture is 4-6 lbs. of pure live seed/1000 sq ft and a complete renovation is 6-8 lbs. of pure live seed/1000 sq ft. After seeding, water frequently and lightly enough to keep the soil dark, but not so much that it glistens (2-3 times a day). 
     Last but most importantly, you must know the size of your lawn to accurately apply fertilizer or seed. Try the lawn fertilizer calculator here - http://agebb.missouri.edu/fertcalc/. If you don't know the lawn size, or want to check, this web application will direct you to Google maps so the size can be estimated with satellite imagery.
      After using the spreader, blow the seeds and fertilizer back off the curb, road, sidewalk, or driveway and back into your lawn. Don't pollute!
 
Zoysiagrass- Warm Season Grass
     Zoysia starts shutting down, and mowing will be less frequent.
If you did not fertilize during the summer, or fertilize enough, (~ 1 lb. N/1000 sq ft) be aware that low nitrogen can result in increased winterkill during tough winters. A light rate of a fertilizer (0.25-0.5 lb. N/1000 sq ft) with both nitrogen and potassium may aid in winterkill avoidance.
Fall vegetable gardening
     A fall crop of cool season greens and radishes is possible if you plant soon. Radish varieties, such as Cherry Belle, Easter Egg, and French Breakfast, are ready to pick in 25-35 days after planting. Many radish varieties do well in cool temperatures. Be sure to water seed beds and keep the soil moist until the seeds germinate. After germination, water at least once a week. Thin radish seedlings to about 1 inch apart to give them enough room to grow tasty roots.
     Arugula and leaf lettuces, such as Black-seeded Simpson, are tasty, nutritious cool season crops that can be started in September. Both take about 40 to 50 days to harvest.
     Consider setting up high and low tunnels to extend the growing season.
     Remove any diseased or insect-infested plant debris from the garden to prevent the pests and pathogens from over-wintering.   This will help to limit populations next year.
     Keep harvesting ripened tomatoes and "top off" plants to encourage additional ripening as the first frost approaches.
     Feel free to contact me if you have more fall gardening questions. Cathy Bylinowski, Horticulture Instructor, [email protected].