How to Keep the Deep Green in Your Winter Lawn
After you go to all the trouble of overseeding your Valley lawn with perennial ryegrass, you will want to keep it looking lush and green all winter long. The correct fertilizers are the key. Here’s a quick rundown of the winter turf fertilizer products you will need and why.
Understand the Numbers on the Fertilizer Package
Forget anything that says “all purpose,” because all fertilizers are not alike. A winter lawn needs certain nutrients. First, it will help you to know that commercial fertilizers show a ratio of three numbers, like 15-15-15. Referred to as “NPK”, the ratio describes the product formulation in nitrogen (N), potassium (P) and phosphorous (K). So, a 15-15-15 fertilizer formulation means 15 parts nitrogen to 15 parts potassium to 15 parts phosphorous for any given quantity of the product. Some fertilizers have other additives, which is important to know for your winter lawn.
The First Fertilizer Formulation for Germination
To help the ryegrass seedlings develop root structures, they need extra phosphorous. Ammonium phosphate is a good choice, with a high phosphate ratio of 16-20-0. 6-20-20 and 16-20-20 are also good choices. Follow the package directions for application rate by square footage. Apply this first formulation of fertilizer when you begin watering your newly laid seed, and again two weeks after seedling emergence, which should be about one month after laying down your seed. Always water your turf well after fertilizing.
The Second Fertilizer Formulation Until Spring Temperatures Rise
After you apply the first phosphorous-rich fertilizer, use a more nitrogen-heavy fertilizer formulation every month thereafter until spring. Formulations like 34-0-0, 21-7-14 and 22-3-9 are good examples. Perennial ryegrass benefits from a fertilizer with added iron because iron is not as plant-available in cool soil temperatures. If there is the danger of frost and you have the option, a foliar fertilizer is preferable to a granular one. Always follow the manufacturer’s instructions and be sure to water the fertilizer in well. Be aware that products containing iron stain hardscape materials.
For information about diagnosing and treating your winter lawn for nutritional deficiencies, refer to the Arizona Cooperative Extension Turf Tips article at turf.arizona.edu/tips1195.html.