Fertilize in Colorado

When is the right time to fertilize in Colorado?

Rather than fertilizing in the early spring, it is better to wait until the late spring, (late May/early June) just before the heat of summer begins. This is preparing the grass for summer when it slows down carbohydrate production and begins utilizing the reserves. A substantial feeding of  3/4-1.0 lb of slow release nitrogen will allow the plant to re-build  it’s energy (carbohydrate) reserves and ward off the stresses of summer like drought, heat, traffic, disease and insects. An IBDU or polymer coated slow-release fertilizer can feed the grass for up to 12 weeks.

Nitrogen is the most important nutrient for promoting good turf color and growth. Do not overstimulate the turf with excess N, especially during the spring and summer. Table 1 suggests nitrogen application programs for various lawn species. To obtain a high-quality, water-resistant turf with greater pest resistance, follow the suggestions in the table.

Over fertilization can contribute to thatch buildup and increased mowing requirements. Avoid under fertilization of bluegrass and ryegrass. These species can become unhealthy if not fertilized properly. Turf that does not respond to nitrogen fertilizer may be lacking in other nutrients, such as phosphorus or iron. Get the soil tested to determine which nutrient(s) are deficient.

Balanced or complete fertilizers contain various amounts of phosphorus, potassium, iron and sulfur. They are a good safeguard against a potential nutrient deficiency. If you leave clippings on the lawn, these nutrients are recycled from the clippings. If you remove clippings, this type of fertilizer is appropriate.

Table 1: Fertilizer application schedule for established Colorado lawns.
Turfgrass Species Mid-March to April1 May to mid-June July to early August Mid-August to mid-September Early October to early November2
(nitrogen application rates are in pounds of nitrogen per 1,000 square feet of lawn area)
High MaintenanceBluegrass/Ryegrass 1/2-1 1 not required 1 1-(2)
Low-Maintenance Bluegrass 1/2 1/2-1 not required 1 (1)
Turf-TypeTall FescueFine Fescue 1/21/2 1/2-11/2-1 not requirednot required 11/2-1 (1)not required
Buffalograss/Blue Grama/Bermudagrass Apply no N 1/2-1 1/2-1 Apply no N Apply no N
1 The March-April nitrogen application may not be needed if you fertilized late (September to November) the previous year. If spring green-up and growth is satisfactory, delay fertilizing until May or June.2 When grass is still green.Optional N applications shown in (). Use extra nitrogen applications where a higher quality turf is desired or on heavily used turf.
Make the final fall nitrogen application (October-November) while the grass is still green and at least two to three weeks before the ground begins to freeze in your area.
On very sandy soils, do not fertilize turf after late September. Nitrogen can leach into groundwater during the winter months. Use slow-release nitrogen fertilizers (sulfur-coated urea, IBDU and natural organic-based fertilizers) on sandy soils throughout the year to reduce the potential for leaching losses.
Nitrogen application can often be reduced by 1/4 to 1/3 when grass clippings are returned to the lawn during mowing. Nitrogen and other nutrients contained in the clippings are recycled into the lawn as they decompose. Grass clippings do not contribute to thatch accumulation in lawns.

Give us a call (719) 963-6267 to schedule your Late Spring fertilizer treatment or click here to learn more about our fertilizer treatment in Colorado. 

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