Friday, August 7, 2015

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The "Key" to Seeding a Better Lawn

Spring has sprung, but fall hasn't fallen as far as lawn renovation goes. People are often surprised to learn that mid-August through mid-September is the very best time of year in northern Illinois to seed for a better lawn.

Why is it the best time? Because our dominant lawn grasses, Kentucky Blue (for sun) and fescues (for partial shade) are cool season grasses. They flourish in the cooler conditions of spring and fall. They slow growth or go dormant in extreme heat and/or summer drought unless we irrigate. Fall also means dramatically less weed competition for newly seeded lawns than spring.

How to seed? The Key

A. Assess the lawn, lawn seems "thin"

Does the lawn have less than 50% desirable grass? Is it overrun with aggressive perennial weeds (tall fescue, creeping Charlie, etc.)? Consider a complete kill, then rototilling or slit-seeding* and starting from scratch.

To buy seed, determine:
1. Total number of hours of full sun and shade the site gets.
2. If there is shade, is it dappled with sun coming through trees, or is it sunlight-free?
3. Approximate number of square feet of area to be seeded.
4. Whether you need sun, part shade, shade and a dense shade mix. All are available.

* Slit-seeding involves the use of a heavy walk-behind machine that slices through soil or lawn, dropping seed directly into furrows in the soil. It's awesome as far as I'm concerned, whether you're seeding bare soil or into the thatch of a problem lawn. The best parts of my lawn are where I did a total kill, then slit-seeded with a high quality seed. Seed is an inexpensive part of the solution, so buy the best.

Grass seedlings emerging from slit-seeding

B. Seeding bare soil 
Buy 1# of seed per 250-300 sq. ft. of area.
1. Best results come by cultivating and loosening the soil to a depth of 3-6".
2. Rake level, doesn't have to be "potting soil-perfect". Large clods should be broken up.
3. Depending upon the size of the area best seeding results will be achieved with a spreader. Use the spreader setting specified for the brand and spreader type you have. Settings aren't interchangeable from one company's spreader to another!
Common mistake - Don't be tempted to apply seed too heavily. It shouldn't be clumped. You should be able to see a small amount of soil between seeds.

Proper distribution of seeds

4. After spreading the seed, lightly raking or gently tamping the soil surface is a good idea to make sure the seed is in good contact with the soil. Don't bury it. If you want, you can add a thin, thin layer of topsoil or compost, NOT peat moss.
Important - Use a starter fertilizer containing the phosphorous seed needs to develop strong roots. Phosphorous is the middle number in the analysis 24-25-4 or 3-6-3. And nope, it doesn't matter whether you put it down before or after seeding that same day.

Watering now becomes the most important thing you can do to ensure a successful seeding.
1. Gently dampen the soil surface regularly.
2. When the soil surface lightens in color you should water.
3. On a hot day with drying surface winds you might have to dampen morning and evening.
4. Don't flood- dampen means water isn't standing and seed isn't floating.

Depending upon seed type, weather and moisture conditions it will take 7-21 days to germinate and show green "fuzz". That's when you must keep up the dampening until the root system is established. Consider mowing when the grass reaches 3" or so.

C. Overseeding (seeding into existing grass to thicken it up) is done at half the rate of bare areas. If the lawn has 50% or more desirable lawn grasses you have choices.
1. Lawn is not compacted, has less than 1/2" of thatch (the spongy layer of undecomposed stems) at the soil surface. Then rake lightly, use a starter fertilizer and follow watering instructions.
2. Lawn is compacted, has more than 1/2" of thatch, is generally thin. This is where you need to consider core-aeration. A core aerator is a neat (and heavy) machine that has empty tines that pull plugs of soil as it is pushed over the lawn. The soil plugs drop onto the surface of the soil, leaving shallow holes in the soil. This allows air, water, nutrients and seed to get right into the root zone. In my humble opinion, well worth doing ... professionally. After core aeration use a starter fertilizer and follow watering instructions.

Core aeration plugs

A better lawn is just a few key steps away!

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