One of the most important things in caring for your newly hydro seeded lawn is proper watering. Kept moist your lawn will grow quickly and thrive. You want to water 2 times a day (3 in hot weather on days it does not rain. You want to be careful not to over water. Don't let it puddle or run off. Puddles can drown the seed and run off can cause seed to be eroded away on slopes. If you underwater you run the risk of weed problems since weeds can grow in drier soil and it is depriving your lawn of the water it needs and possibly killing all or part of your turf area. Frequent light watering is preferable to infrequent heavy soakings. It is extremely important to keep the seed bed moist continually until just before your first mowing. Once you have mowed you can reduce watering.
You should begin mowing when your grass is approximately 3" tall. Mowing once per week is sufficient. Typically the first mowing will be in about 3 weeks after seeding. This may be slower in the early part of the year when soils are still cold or in the hot summer. Once you start mowing, your lawn will quickly become thicker and more beautiful. It is recommended to use a bag for your first few cuttings. Once your lawn is fully established you can use a mulching mower.
We apply a high phosphorus starter fertilizer when we seed. Starter fertilizer has ingredients that promote healthy roots. We feel a strong root system is important to create a healthy lawn. Once your grass is growing and after the first mowing we recommend applying a high nitrogen fertilizer such as Scott's Turf Builder (but not Turf Builder + that includes a weed killer.) Be careful not to over apply. Once you have applied fertilizer your lawn should quickly fill in and become a dark green, beautiful lawn.
Unlike straw that some people use as a mulch when seeding, hydro seeding mulch contains no weed seed. You may have weeds come up with your new grass. Your soil and any top soil you bring in contains weed seed. Nothing in our mix has weed seed! Weed problems are more likely to occur in lawns that were not sufficiently watered and in lawns planted in the summer. The first 3 months we do not recommend using any kind weed killer. Many weeds can be controlled through mowing. If you have crabgrass it is better treated early in the spring of the following year with a pre-emergent crab grass preventer.