Question
Dear Kenneth, thanks for volunteering.  I live in Western Connecticut.  Our lawn is 1 acre of partial sun/shade. I'm curious about the benefits of lime and fertilizers.  The Scott 1,2,3,4 program sounds easy enough but I'm wondering if I should lime as well. (and at the same time) Also, if I decide to over seed for increased thickness, should I not use the Scotts number 1 thoughout? Lastly, are the various brand names generally the same. (Scotts, Agway, Greenlawn) Scott's is much more costly, but not as much as using the lawn doctor service. (a whole other question) Thanks again.

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Answer
Plants (incluing grass plants) are very unique in the sense that they can manufacture their own food. To do this they need ingrediences, such as carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, sulfur, magnesium, calcium, boron, etc, etc.

A total of 17 individual nutrients are needed in the right amounts to grow. Carbon, oxygen and hydrogen are taken in as carbon dioxide and water. Although the atmoshere contain vast quantities of nitrogen, most plants can not use these as the molecules are tied very close. Instead plants take up nitrogen from the soil together with other nutrients such as phosphorus, potassium, calcium, mangesium, etc. These nutrients enter the roots dissolved in water.

All 17 nutrients are needed for proper plant growth. No single nutrient is less important than others, but the individual nutrients are needed in different quantities. Typically the soil already contain amble supply of most of the micro nutrients (boron, aluminium, maganese, etc) but the nutrients which are required in larger quantities: nitrogen, phosphorus, potassium, etc must be resupplied because a healthy lawn usually deplete these resources faster than nature can resupply manually.

This is why we fertilizer: to re-supply nutrients which are depleted by the lawn. A lawn is not a natural occurance and in nature you would not find a lush carpet but individual clumps of grass which would vary their position from year to year to match areas of soil with amble supply of nutrients. In a lawn we must resupply these nutrients a couple of times per year if we want to maintain a healthy lawn.

As long as you buy fertilizers formulated for lawns (e.g. as opposed to flowering fertilizers for example) then the brand really does not matter. Agway or Greenlawn are fine alternatives, too. Scott's is just be best known company. Branding is everything.

I do not recommend the Scott's 4 step program. Too much emphasis is put on herbicides and insecticides (weed and insect killers) and fertilizing is not done at the right times for a cool season lawn. I like the Scott's product line, but I recommend another fertilizer scheme. You can also buy other fertilizer brands.. that is fine.

Fertilize your lawn in late spring, early fall and late fall. E.g. mid May, early September and late October. Do not fertilize during hot summer months or too early in spring. I recommend buying fertilzier WITHOUT herbicides/insecticides.

Apply fertilizer to a dry lawn and then water in with plenty of water. You can also apply when rain is anticipated.

If you have problems with broadleaf weeds (wild strawberry, dandelions, clover, etc) pickup a bottle of WEED-BE-GON and spot spray directly on the leaves. If this is too much trouble, you can use the weed-and-feed products (e.g. broadleaf weed control products mixed with fertilizer) but I really prefer to fertilize and fight weeds seperately.
As mentioned above, fertilizer should be applied to a dry lawn but for the herbicides to stick to the weed leaves, the weed-and-feed products (combination fertilizer/broadleaf herbicides) must be applied to a WET lawn and the product left on the leaves for 24-48 hours before watered in. This is not ideal as fertilizer should really be applied to the soil and watered in immediately. Therefore I don't like weed-and-feed products and prefer to fertilize seperately and fight weeds seperately, but you CAN use them if you like. use them in late may and/or early september as needed.

Liming is done to correct the pH value of the soil. Most soil in our area will be naturally acidic (e.g. low pH value) and lime (calcium) will raise the soil pH. Grass grow best at soil pH around 6.0-7.0. If your soil pH is below 6.0 then liming would be in order. If your soil pH is above 6.0 DO NOT LIME. Liming should not be done automatically. It should ONLY be done if needed. You can buy pH test kits at garden centers, but a better (more precise) result is had if you mail in a soil sample to your local county extension office (see link). UCONN will do this for Conneticut.

They usually test soil for a nominel fee ($10-15) and will send you a written report. Such as soil test also reveal if any other nutrients are in deficit.

Too low pH level will make heavy metals such as aluminum and iron very mobile in the soil and that can cause nutrient toxicity to the plants (the plants get too much of these essential nutrients). Too high pH will tie up nutrients such as iron and phosphorus. Therefore the goal is to balance pH around 6.0-7.0. This can be done by liming once every year or every 2-3 years. I recommend a soil test before liming. If you have not fertilized this spring, take the soil sample now, otherwise wait at least 60 days and take soil sample before fertilizing again.

Since Conneticut typically has acidic soils due to high rain fall amounts, annual or every 2nd year liming applications are normally done to keep soil pH stable. I strongly recommend a soil test, however.

e.g. in summary:
- have a soil test done to determine pH. Only lime if pH is below 6.0 (see link for UCONN).
- fertilize in late spring, early fall and late fall. avoid fertilizing during hot summer months or too early in spring.
- do fertilize to maintain healthy grass growth
- apply to a dry lawn and water in, or apply when rain is anticipated
- if you use weed-and-feed products, apply to wet lawn and leave on grass for 24-48 hours without washing off.

Good luck


Link:
http://www.canr.uconn.edu/plsci/stlab.htm