Agdex No. 273.21
The preparation of the seedbed is the most important aspect of establishing a good lawn. All common lawn problems, such as insects, diseases, weeds, and summer browning can be minimized or prevented by starting with good soil conditions. A lawn requires at least 10-15 cm of good topsoil. Heavy clay soils can be improved with an addition of sand or organic matter. These materials loosen and aerate the soil. Organic matter mixed well with very sandy soils will improve the water holding capacity of the soil.
Most New Brunswick soils are acid and require lime to raise the pH so it is in the range of 6-7. A soil test available through the New Brunswick Deptartment of Agriculture, Fisheries and Aquaculture will test the pH and advise on the amount of lime required to raise the pH to the appropriate level. For the average soil 50-100 kg of lime per 100 m2 should be worked into the top 5 cm of soil before a lawn is seeded.
Fertilizer supplying 1 kg of phosphate (P2O5) and potash (K2O) per 100 m2 should be incorporated into the soil prior to planting as grass seed has only enough stored nutrients to grow for a few weeks. Use a complete fertilizer with a 1-3-3 or 1-4-4 ratio to supply the nutrients.
8.3 kg of 6-12-12 or 5.0 kg of 5-20-20 will provide 1 kg of phosphate and potash
A further application of 0.25 kg nitrogen 4-6 weeks after seeding will help maintain vigorous growth in the lawn.
A lawn should be gently sloped away from the house in all directions for proper drainage. Rake the seedbed to eliminate high or low spots and to provide a smooth, even surface. Till the soil enough to loosen it and remove large stones and debris. It is not necessary to till the soil to a fine fluff; soil clumps from pea size to golf ball size are suitable for lawn establishment and less prone to erosion. The final seedbed should be level, firm, and slightly moist.
The lawn can be safely seeded in either the spring (as early as possible) or the fall (mid-Aug to mid-Sept). Before spreading the lawn seed, mix well to avoid uneven distribution of fine seeds. For best coverage sow the seed in two directions as in Figure 1 Seeding pattern for lawns.
Raking lightly after each application of seed with a bamboo or leaf rake. After seeding is complete roll lightly with an empty roller to press seed into close contact with the soil. Do not cover the seeds completely. For the first 2 weeks keep the seedbed moist at all times to germinate the seed. Once the seeds are established avoid light waterings as they promote shallow root growth. Moisture should penetrate the soil to at least 10cm depth. Avoid walking on, or in any way disturbing, newly seeded areas.
SEED AND SEEDING RATE
It is important to use the best possible lawn seed to establish a healthy attractive lawn. There are many seed mixes available designed for various lawn requirements. A seed mix for general use in the landscape should include 40-60% Kentucky bluegrass, 20-40% creeping red fescue and 10-20% perennial ryegrass . The recommended seeding rate is approximately 1.5 kg per 100 m2. Shaded locations require different mixes to grow a good lawn. A general mix for a shaded location should contain about 20& Kentucky bluegrass, and the remainder should be recommended shade grasses (e.g. creeping red fescue and redtop). The recommended seeding rate for shade mixes is approximately 2.0 kg per 100 m2. Commercial lawn seed mixtures are graded Canada No. 1 and Canada No.2 with Canada No.1 being a higher quality seed mix.
Mulch applied after seeding helps to keep the seed in place and conserve moisture. Mulch is more important on areas that are prone to erosion. Chopped straw (1 cm thick) is a good mulch for a newly seeded area.
A well fed lawn wears better and is more resistant to insects, diseases, and weed infestation. A lawn requires about 1.5 kg of nitrogen per 100 m2 per season. Using a regular fertilizer the nitrogen should be split into 2 equal applications: mid-June, and mid-August. An additional application of regular fertilizer (.5 kg N) in mid-October can be added to promote early spring green up the following year. For best results use a lawn fertilizer with an N:P:K ratio in the 4:1:1 range.
Various slow release lawn fertilizers are also available. These make nutrients available to the grass over a longer period of time (the time is related to the slow release formulation used). If a slow release fertilizer is used, a single application in June should be sufficient for the season. A mid-October (.5 kg N) application of regular fertilizer can be added to promote early spring growth.
Annual lawn maintenance keeps the lawn attractive and healthy. A lawn should be mowed regularly to a height of about 4-7 cm. No more than 1/3 of the foliage should be cut at one mowing. If more than 1/3 is removed most of the food producing portion of the plant is removed weakening the grass. Grass clippings breakdown rapidly, so it is not necessary to remove the clippings from the lawn unless they are in heavy clumps. Clippings left on the lawn are a good source of recyclable nutrients.
In dry periods of the summer, watering is beneficial to maintain a green lawn. Grass should be thoroughly watered to a depth of 15 cm; avoid light waterings as they promote shallow root growth. Morning or midday watering is preferred because the leaves dry quickly minimizing disease problems.
Maintaining a healthy vigorous lawn is one of the best methods of weed control. Carefully applied herbicides can also be used to control problem weeds.
For more information refer to New Brunswick Dept. of Agriculture, Fisheries and Aquaculture Publication 'Weed Control In Lawns'.