Question
We've lived for 25 years with a lawn that to begin with was not great and over the years has severely deteriorated.  This year it has become basically a weed field of both annual weeds like crabgrass and goosegrass (this despite generous corn gluten treatment in spring -- yes, when the forsythia bloomed) and perennial weeds, the worst of which are an ocean of wild violets and tracts of yellow oxalis.

We live outside of Philadelphia, PA.  Our soil is acidic and clayey.  (Yes, I've tried lime, but not consistently, since it seemd to make no difference.) Various parts of our lawns (front and back) get sun for half a day; perhaps a few spots get more; the rest gets less.

We usually get good spring rainfall and adequate rain through June.  July and August bring a near-drought most years.  Yes, I do water deeply (though this year I  haven't, because I am in despair).  For years we have mowed the summer lawn to a height of 3 inches and left the clippings.    

We gave up chemicals at least twenty years ago and have used organic fertilizer every year, sometimes twice or even three times.  No luck.

The actual grass is now less than 50% of the lawn area.  Most prevalent are wild violets.  No, I don't think I could resign myself to learning to love wild violets.

I realize that (a) our soil is poor; (b) we haven't been reseeding and (c) we don't know what kind of grass would grow in our lawn; and that (d) wild violets and oxalis are diabolical weeds to try to eradicate.  I am wondering whether we need to kill everything, including the remaining grass, get the soil amended by having compost and topsoil tilled in, and start all over with a better grass?  If so, what is the best way to kill all the lawn vegetation with as little harm as possible to adjacent flower beds and to the soil?  How could we be certain that the vile violets are really dead and not just stunned or dormant?  And what soil amendments are needed?  And what would be the best choice of grass, or a mixture, for our not very sunny lawn?

Unfortunately, my husband and I are not in a position to do this ourselves for the ca. 10,000 square feet involved.  We do have a garden helper, but is this the kind of work that a lawn company of some special sort would do for us?  (So far I've made a number of phone calls but haven't found one that will renovate or replace an existing lawn.  Neither will the landscapers I've contacted.)

Or, do you think there is a less radical and more do-able solution?

Many thanks for whatever you can think of.

Answer
Dear Gabriele:

What a detailed yet poetic description!  You have been patient.  Keep in mind that August must be the month of depression for gardeners.  I stop weeding this month and estivate.

You are in a region which supports bluegrass.  It is the finest winter turf I know.

Your choices are to remain purely organic or use a hybrid system to build your turf which can be abandonned later for a cleaner management once the lawn has recovered.  I also use this system to correct problems, but do not hold to it once results are good.

For the first strategy, renovation, I would recommend using compost to build your soil and turf.  Topsoil only if you have rocky or really bad soil areas.  Apply one to two cubic yard of high quality compost per one thousand square feet.  Till in.  Make final finished grade and sew grass.  Water until two or more leaves per plant show.  Then, reduce watering so roots develop.

Preparation for this may be a total eradication of  weeds and grass with a broad specturm herbicide, Roundup or like (glyphosate.)  Second choice for eradication is a mixture of 2-4D with additives for your weed mix.  Should you decide on this path, check with local ag agent to determine which to use, when and how.  There are many mixes, all of which have special applications.

With the first choice, renovation may take place within a week or two of application (Roundup or like.)  With second, wait to see how weeds respond.  Decide whether to make second or third application.  Then renovate.

Careful application is the key to avoiding collateral damage.  Think of this as a one time crossover.

The persistent problems will be violets, oxalis, and weed grasses.  These will have to be discouraged with pre-emergent herbicides over the next few years, and may never disappear entirely.  All of the weeds above seed annually and there is a bank of seeds in your lawn soil to discourage for many years to come.

For source of compost, I am sure that there are several professional suppliers of compost in that area.  They should have high quality material.  It should be thermophilically processed (131 deg F+ for weeks), of fine texture, black and rich in nutrients.

I am surprised that your landscapers do not wish to do renovation.  I found it to be good business and profitable. HOwever, it was always done at one time of year, and we were rushed to do all the work.

If you are really unhappy with the lawn and want results, follow plan A or plan B for eradication of weeds and renovate.  If you can wait for results, start on a complete program of herbicide applications, fall, winter, spring and summer to gain control.  Apply compost in fall with overseeding and aerating, 3/8 inch (or one cubic yard (CY)) per thousand square feet (M) over top of the bluegrass seed.  This will take a few years to get good results and herbicide program is extended longer.

Either one will take patience.  Bluegrass will not usually cover in one year following renovation and pre-emergents and broadleaf herbicides must be used in the interim.

The second choice of stategies will require a few years to get high quality results with fall overseeding and compost application for two years at least.  Follow this with a spring boost of 1 pound of nitrogen (N) per M, any source N.

Best wishes.