St. Augusting Grass in new Home

mrwizard93 – posted 07 September 2006 11:34

My home is a little over 2 years old. When they put down sod in my lot, they neglected to place a good layer of soil underneath the grass. In some spots I barely have a layer of soil before you get to the compacted fill underneath. After a year or so of care after we moved in, we finally got the grass looking a bit respectable. Now, after a short and really dry late winter early spring I am being overrun by crabgrass, some fine grass with a dense root system, and about 10 other types of weeds that are driving me nuts. It seems as thought the weeds love the shade and the areas that collect water the most. Should I spread soil over my lawn, maybe sand? I fertilize regularly, cut biweekly. and I live in Florida so I rarely water during the summer. Am I just out of luck and should tear up the whole thing and start over? I would not like to do that because the cost would be too high but if I do should I go with St Augustine grass again?

TexanOne – posted 08 September 2006 00:48

What is the underlying compacted fill made of?

mrwizard93 – posted 08 September 2006 08:13

Not good … I have compacted limerock. And it is pretty dense material.

mrwizard93 – posted 08 September 2006 08:15

And i forgot to mention that it is almost like concrete, so it is not like i can get someone to come out and aerate.

TexanOne – posted 09 September 2006 00:04

You should be able to naturally convert the compacted lime rock into soil with the right amendments and of course, with time. The last thing I would do is attempt to excavate the compacted stuff out and replace it unless the substructure is just inorganic trash (like an old landfill).

I don’t know what concoction of natural ingredients would be used in Florida, but I would think a knowledgeable local nursery would know for your specific conditions. Surely you aren’t the only victim of this in your area and a solution is available.

In West Texas, we have a very similar subsoil condition with many soils having a thick layer of underlying caliche (a pinkish/white, solid, very hard, calcium carbonate rock layer). Caliche is probably one of the most alkaline and unfriendliest substances around for any plant. It’s used for paved roadbeds, slab foundations, and for unpaved ranch roads because weeds will not grow in it or through it. When my house was new, the contractor spread a good topsoil over the native soil which was nothing but a gravelly clay sitting on top of a 4’ thick caliche layer. Over the years and with the help of natural amendments, the underlying caliche has been largely broken down into an acceptable course loam – but it took 10 years.

One of the techniques used to break down underlying caliche is to use a combination of Humic Acid that is applied at 10-lbs / 1000 sq ft with a fertilizer spreader and earthworms. It is actually possible to for humic acid and earthworms over 3 to 5 years to convert caliche into a suitable growing media. Turfgrass roots will also convert most hardpan into soils over time, but it takes decades to do this without the help of soil conditioners.

Maybe someone else in this forum will jump in with the stuff you need for your specific situation. At any rate, I would recommend you check with the local nursery folks to see what they recommend too.

hankhill – posted 10 September 2006 00:26

If it’s strong enough to break down limestone, I’d be worried aboutthe foundation of the house. Concrete doesn’t like acids.

[This message has been edited by hankhill (edited 10 September 2006).]

mrwizard93 – posted 20 October 2006 13:59

So does anyone have a way of getting rid of the crab grass other than blow torching the whole yard and starting over … The crab grass is the real pain in the rear. I tried using a weed killer, Ortho Weed-B-Gon MAX Weed Killer, to get rid of the overall weed problem and it ended up killing my lawn and and most the weeds EXCEPT the crab grass even thought it was supposedly safe on St Augustine grass. I am pretty sure i have St. Augustine grass and not flortram. Is there a definitive was of telling the difference. Now I am starting to get a nice lawn of crabgrass. What should i do.

hankhill – posted 20 October 2006 17:49

Crabgrass is not perennial. All you haveto do is remember to put down pre-emergentnext Spring and it’s gone.

mrwizard93 – posted 23 October 2006 06:24

What kind of pre-emergent treatment is recommended? Is there a specific product or brand that seems to work best for south florida?

Thanks a ton!

hankhill – posted 23 October 2006 23:02

No idea for Florida. I used Pre-m during the fall & winter (two treatments), andDimension for the final (spring) treatment in central Texas.