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Saturday, September 10, 2011

Fall Lawn Replacement in the Hot Desert

Upper surfaces of grass blades can help identify
which type of grass it is: L to R, Kentucky bluegrass,
perennial ryegrass and tall fescue
 Q. I need advice. We planted about 100 square feet of sod a couple of years ago. It had been doing quite well. I believe it was over fertilized 5-6 weeks back.. It is now very brown and not responding to watering. I plan on replacing it with new sod once it cools down. My question is, can I put the new sod over the old or pull out the old and re-prep the sub base? Any advice would be appreciated.

Sod removal using a sod cutter
A. You didn’t say what kind of sod it is but I am assuming it is tall fescue. Tall fescue represents about 98% of all lawn grasses in the Las Vegas area due to its tolerance, for a cool season grass, to our high summer temperatures. Before you do anything make sure it is dead. Tall fescue can appear dead but if you see any green at all at the base of the dead grass then it may just have died back.

Tall fescue is very drought resistant even though it uses a lot of water. It can dieback when water is not available and sit there for quite awhile appearing dead and then re-emerge from grass that looks dead and start growing again. This might take a couple of weeks of applying water after it turned brown. It might then be a bit sparse and you may have to seed into the grass again to get it to fill in those bare areas that didn’t make it.

Power rake, aka dethatcher aka verical mower used for
removing thatch, slicing stolons and improving
water penetration to turfgrass or lawn.
However, if it did turn brown due to a heavy fertilizer application then that is salt damage and tall fescue is not all that good in its tolerance to salt and then it is very probable you are right. You have two alternatives in replacing the sod. One is to rent a sod cutter and cut the old sod out leaving behind a ready made surface for resodding. Or you can try digging it out by hand and leveling the surface in preparation for the new sod. A lot of work. You will not be able to put new sod on top of the old sod. The old sod will leave an “interface” that will cause all sorts of problems for the new sod.

There is still yet another alternative worth considering. The dead grass is a perfect seedbed for seeding a new lawn. In about late September to mid October mow your dead lawn as short as you can and use your bag on the mower. Don’t mulch the dead grass back into the dead lawn. Next rent a power rake, sometimes called a dethatcher, and dethatch the dead lawn deep enough (you can adjust it) so that when you make a pass or two you can see soil between the dead grass blades. It is important to see bare soil throughout the dead lawn.

Patchy look to a lawn when a coarse textured grass is seeded
into a finer textured grass. An example would be seeding
K31 or Kentucky 31 tall fescue (a pasture grass) into bluegrass or
even a turf-type tall fescure with a finer texture
Purchase good quality tall fescue grass seed, 100% tall improved tall fescue and not Kentucky or K31 tall fescue, the cheap stuff. Apply a starter fertilizer such as 16-20-0 or any fertilizer high in the middle number(in this case 20) but having some of the first number (in this case 16). Seed at about 10 to 12 lbs of seed per 1000 square feet and topdress it with topdressing or steer manure with NO MORE than about 1/8 inch of topdressing. It is best to do this with a roller for applying this stuff. You can rent one from most rental places. Irrigate about three times a day for a few minutes each cycle. Irrigate long enough to wet the topdressing but not long enough to cause it to run off of slopes or puddle. Do this about 8 am, 1 pm and 6 pm. Your biggest challenge will be keeping the pigeons and other birds off of your seeding. Reduce your watering to once a day when you see grass emerging usually in 7 days or less.

A wild idea would be to not use tall fescue but a different grass seed that has high tolerance to heat in our area and a much softer feel to it. These are the heat tolerant perennial ryegrasses. They are superior to tall fescue in feel and water use but you have to get the right kind of perennial ryegrass. Some perennial ryegrasses are very heat tolerant and others are not at all and will burn up when it gets hot in the summer.

One of the best of the perennial ryegrasses is a combination of Palmer and Prelude perennial ryegrasses. It has been used on golf courses for nearly 30 years now here and does very well in the heat. You can mow it short as close as ½ inch or less (if you seed at the right rate for this kind of cut) or even up to two inches. It is soft to the touch, unlike tall fescue which has tiny hooks on the edges of the leaf blades that can cause “itchiness” some people think is an allergy which it is not. The problem is that it is only available in 50lb bags. This seed blend is available in Las Vegas from Helena Chemical Company but it will be pricey in that quantity. I could not find it on the internet in smaller quantities.

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