Yellowing of grass
I moved into my home here in Hyde Park two years ago and had Robin's Nest Landscapers remove island beds from my lawn. In the attached photo there was also a 'fire pit sitting on paving stones' that was also removed. Robin's Nest reseeded the grassless patches with a seed that they told me is their Delmarva blend. After one year I noticed that the bare patches were not sprouting new grass. So I dug out the weeds that did take root and used the Scott's EZseed in that area. Initially the grass came in very well and was truly green in color. You can see in the attached photo the grass is now a yellowish-brown color with a smattering of green grass blades. That grass is growing, though, because if I don't mow it, it will grow more over the course of 5-6 days. I cut my lawn to 3.5 inches and water it regularly. You can see that there are areas of green grass surrounding this yellowish-brown patch. I measured the pH of my soil with a device that has a 8-3.5, alkaline to acidic, scale. It measures at 8. Also during the fall and at the start of the spring the grass was green. If the hot, drier weather is a factor, why hasn't my entire lawn been affected and turned this non-green color? Thanks for your advice and let me know if I should collect soil samples for you.
Talbot County Maryland
Your photo shows a fairly large area of yellowing grass. Does it seem like the problematic areas are where the beds and paving stones were? The soil can be very compacted in these areas preventing the grassroots from penetrating into the soil so when the weather turns hot and dry it begins to turn yellow. The rest of the lawn stays green because the soil there is not compacted.
You should test the soil using one of the soil labs we recommend. For you, that would be the University of Delaware. See the following information, http://extension.umd.edu/hgic/soils/soil-testing
To improve the soil compaction you can rent a core aerator that pulls plugs of soil out of the ground. When you reseed use the Delmarva blend and not the Scott's product. If the soil is really compacted in the area you may need to consider tilling the area and working in compost or organic matter into the soil. Aeration and lawn renovation should be done in September.
To reply to your question about whether the yellow color matches where the paving stones had been removed by the landscaper. That is not the area in the photo I sent you. The photo is just above that area. Overall I agree that my soil seems compacted, but I am so new to trying to maintain a lawn I have no good reference what is typical or not.
But I think I may have another idea of what the problem is. After I submitted my question, I went outside to read a magazine while sitting in the shade of my maple tree on the eastern edge of my lawn. As I sat there and watched the shadow of the tree move across the lawn with the rising sun, I noticed that where ever the shadow moved across the grass, the grass was green, in fact very green. The part of my lawn that I sent you a picture of, receives no shade at all, neither from trees or the height of my house. I looked at my neighbors yards and also noted that where ever there was tree cover over the lawn, providing some shade during the day, the grass look quite green. Elsewhere it is yellow like mine. So I am wondering if I just need to water more where there is no shade on the grass so that there is less evaporation and it retains more water. Right now I water for 30 minutes with an oscillating sprinkler until my entire lawn has been watered. I read that a lawn needs 1 to 1.5 inches of water a week, and that 30 minutes of watering should give the lawn about 1/2 inch. So watering twice a week should keep the lawn properly hydrated. What do you think about my analysis and observations?
Also, I will definitely do the soil test utilizing the University of Delaware. Thanks for that contact information.
Yes, you can be on to something. While grass prefers full sun it seems when our summer turns very hot and dry turf that receives some shade stays greener longer. Since your lawn is fairly new it should be watered. Your watering schedule seems about right. To check you can take a probe (a screwdriver will work) and push it into the soil to test the soil moisture. The soil should be moist about 4 inches down.
We do want to stress that you plant tall fescue seed. A blend of tall fescue cultivars is the best for our area. Look on the grass seed label to see what it contains and avoid those that have perennial ryegrass in the mix. The following is a copy of a publication from the turf research plots at the University of MD that lists the recommended cultivars. http://www.mdturfcouncil.org/resources/Documents/TT-77%202017.pdf
Also is a link to our blog about summer lawn care, https://marylandgrows.umd.edu/2018/06/11/lawn-tips-for-summer-dont-overmanage/