By Judy Bernard, Master Gardener
A question about sod that didn’t root came to our contact email account recently. The person asked what to do about an area the size of about a dozen rolls of sod that didn’t take or thrive. Replace it or seed over? Below is a photo of the area in question. Because this is the time of year that we see these problems, I thought the answer to this question would make a good blog.
Since new sod won’t be available for a few weeks, I suggested to try seeding a small area. If the seed germinates and grows, then go for it! If not, remove the dead sod and replace. If you’re replacing, make sure the new sod is freshly harvested that day. Also, I would add some compost to the soil before laying the new sod. The compost will help the soil retain moisture and provide nutrients.
This time of year is perfect for seeding lawns as usually there is more rain and the weather is cooler, which grass prefers for germinating and growing. Top seeding is usually done on top of existing lawns, so I don’t see why it shouldn’t work on your recent sod.
Rather than topsoil, my suggestion is to use compost. Depending on where you get topsoil, it could be full of weed seeds. You can get compost from most garden/landscape supply places. The City of Peterborough also makes and sells compost which you can buy at Ecology Park or at the Bensfort Road transfer station. Take your own containers. The compost will also help the old sod decompose into the soil.
Before seeding on top of the sod that didn’t take, rake off as much of the loose grass as possible. Put a good layer of compost over that area, 1/2 inch at least. Before seeding, make sure the old sod and the ground are moist underneath. Two and a half centimetres (1”) of rain/water will soak approximately 15 cm (6”) deep.
Then, seed the area with the same variety of grass that is in the sod so that eventually you will have a uniform lawn. Gently cover the lawn seed with a thin layer of mulch by using the back of a garden rake to rake over the area. Water well.
To keep the existing sod healthy, put a thin layer of compost over that as well and rake it in. The compost will help the soil retain moisture and provide all the nutrients your lawn needs without expensive chemicals.