Gardening with Allen: Fall is ideal time to plant a lawn

We have an area where we want to plant a lawn. Is this a good time to start a new lawn or should we wait until spring?

September is the ideal time to start a new lawn or refurbish thin areas in an existing lawn. You can start a lawn from seed now and save a lot over planting with sod. The soil is still warm so seed germinates quickly. Weed seed germination is much less than in the spring. Conditions are ideal for grass growth and development. It is also an excellent time to plant grass sod or hydroseed. However, seeding is the most economical method.

Shallow tilling 2 or 3 inches deep is adequate for seed planting. A rake or multi-tine cultivator is enough to scratch thin areas in an established lawn. Spread fertilizer and seed and rake lightly so that one-third of the seeds are still visible on top of the ground. A light mulch of bark dust or peat moss will help hold moisture near the seeds. A roller can also be used to  help level the soil and firm seeds in place.

Almost any lawn fertilizer can be used. In Washington, lawn fertilizers can’t contain phosphorus, the middle number in a nitrogen-phosphorus-potassium formula. I prefer a 3-0-2 ratio. Typical formulas are 15-0-10 or 18-0-12. One or 2 percent of iron helps to develop dark green color. You will need to check the “guaranteed analysis” for specifics on iron. Fertilizer with slow release or coated nitrogen is helpful in extending the stimulus into November.

The most critical step is frequent irrigation for the first three to four weeks after planting. The ideal situation is to keep the top of the soil moist continually. This means at least three light irrigations a day. If you have a sprinkler system, set it for a five-minute irrigation once every two hours. If you have sloping areas shorter and more frequent irrigations may be necessary to avoid washing. A newly sodded lawn needs once a day irrigation.

This is also the best time to fertilize an existing lawn. Sometimes I split my fall lawn fertilization into two parts — one at half rate now and a second application in late October or early November. The later fertilization carries over into winter and spring and keeps the lawn green all winter. Another approach is to apply full rate now with a lawn fertilizer that contains some coated nitrogen. The coated nitrogen extends the fertilizer release later into the fall. Again, check the guaranteed analysis label for coated, slow-release nitrogen.