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Followup To
Question -
Hi. I live in Cleveland, Ohio. I bought a new house and am trying to care for the lawn. I recently planted grass in areas where grass was dead. The grass came up and is doing nicely. I waited about 4 weeks and then added a middle of the road fertilizer I bought at Home Depot. Now, there are brown areas where I am afraid I burnt the grass. How can I bring these back to life? Also, is there a chemical I can put on the lawn that will kill weeds (mostly dandeylions) but not grass? Thanks so much!
Answer -
When fertilizing following below guidelines:

Never apply more than 1 lb actual nitrogen per 1000 sq feet lawn area. To calculate how much fertilizer this is, divide 100 by the first number on the bag (e.g. if the 3 numbers on the bag is 38-3-3 then you would use 100 / 38 = 2.63 lbs per 1000 sq feet area. If the numbers are 29-3-4 then use 100 / 29 = 3.45 lbs per 1000 sq feet). To find your sq footage use the length of the lawn multiplied by the width. If you have an irregular shaped lawn, divide it up into logical squares, multiply the width x length of each area and add all areas together. e.g. example:
area1: 100 x 72 = 7,200 +
area2: 50 x 20 = 1,000 +
area 3: 20 x 30 = 600 = 8,800 sq feet.
If you bought a 12-2-6 fertilizer you would use 100 / 10 = 8.3 lbs per 1000 sq feet, or 8.8 x 8.3 = 73 lbs for the lawn. If you bought a 29-3-4 fertilizer you would use 100 / 29 = 3.45 lbs per 1000 sq feet, or 8.8 x 3.45 = 30.36 lbs fertilizer for the lawn.

I know fertilizer bags comes with spreader setting informations (and that is ok to use), but I like to make a 'sanity' check. If you calculated that you must apply 75 lbs and you buy 2 x 40 lbs bags you can generally apply both. But if your calculations show that you need 30 lbs and you have a 60 lbs bag then you should not be applying more than 1/2 bag.

I prefer to use a smaller spreader setting than recommended on the bag until I get used to a new fertilizer. I then simply make more passes until the pre-meassured amount has been disbursed. Next time I fertilize, I then open the spreader at bit higher if I had to make too many passes.

Fertilizer should be added to a dry lawn (which is not draught stressed, however) and the product should be watered in immediately using plenty of water.

Always apply fertilizer when the temperatures are above 40 deg F but below 85 deg F.

In your area, it is better to fertilize in spring, fall and late fall, e.g. mid May, early September and late October. Do not fertilize during hot summer months.


The best you can do right now is to water the area throughly to flush the salt through the root zone and then water at least once weekly with one deep watering. In fall, you will note which areas has recovered (may take time). If some area has not greened back up in late August/early September, you may need to re-seed.

Dandelions are broadleaf weeds. I recommend using a product called "Weed-be-Gon" which is sprayed directly on the leaves of the weeds. the product only attack broadleaf weeds (e.g. not grass, but flowers would be affected) and is safe for use on lawns. Do not cut lawn a few days before and after spraying. let the product dry on the leaves.

You can also buy a mixed bag of fertilizer w/broadleaf weed control products, but I prefer to fertilize seperately and fighting weeds seperately. I don't like the combination products such as fertilizer w/weed or instect control.

The weed-be-gon should not be used on windy days or when daytime temperatures are consistently above 85 deg F. You get best result if you spray 2-3 times starting in early fall. You can follow up with spot spraying next early spring if anything is left, but best result is usually had in fall.

Weed-be-gon comes as a spray bottle (preferred) or as a bottle with a garden hose attachement which you then attach, open the garden hose and water the weeds with the mixture.

Excellent answer!! Thank you so much. I would like to ask you that having now fertelized one month ago, is there a product I can use a few more times this summer to give even more health to the lawn? Thanks  

Answer
You get a healthier lawn by not fertilizing during hot summer months.

My recommendation would be to mow 1-2 times per week and mow high. set mower to cut grass at 3.5-4.5" tall (after mowing). Water once per week deeply (e.g. such as for 2 hours to thoroughly wet the root zone to a dept of 8-10") if no rain. These two items will ensure a really healthy looking lawn.

Let me explain to you why I recommend that you do not fertilize now.

grass, like all plants, survive by producing their own food. they convert oxygen, water and nutrients (fertilizer) into foodstuffs (carbohydrates) which is either used for growth or put in storage. Like a factory which either manufacturers for sale or put overflow in storage.

When the grass is prompted to grow, either through natural cycles (moisture, moderate air temperatures, and warm soil etc prompt the grass to grow in spring and fall) or through inducement with nitrogen fertilziers the plants will use these carbohydrates to create leaf material. The faster the growth, the more carbohydrates are used to produce leaf material, etc.

It is important to understand that growth requires carbohydrates. these carbohydrates must either be supplied through active photosynthesis or taken from storage. If the plant cant photosynthesize for some reason, the storage reserves will gradually be depleted. once depleted, the grass plant dies.

Grass in northern areas are cool season plants which mean that they reach maximum photosynthesis potential at relatively low temperatures (60-70's). During months of higher temperatures the grass plants go partially dormant and photosynthesis practically stops. E.g. they can not produce carbohydrates during hot summer temperatures.

As a natural protective mechaism, the metabolism of the grass plants slow down during hot summer months. This means less active growth and less use of carbohydrates. E.g since the grass plants can not produce carbohydrates, the lower metabolism ensures that the stock is not unduly reduced.

However, if you fertilize the grass during these periods of time you may end up in a situation where the grass is prompted to grow actively. as mentioned above, nitrogen fertilziers will prompt it to grow. A lot of leaf material will be created, it will be nice green and lush for that reason. However, since photosynthesis is practically shut down, all the carbohydrates required to produce this leaf material must be taken from storage.

In grass the storage reserves are in the root, rhizomes and crowns.

The aim for a good landscaper is to maximize carbohydrate storage. To do this you must fertilize when photosynthesis potential is high and the natural pull on the carbohydrate reserves are low. This would be late spring, early fall and late fall.

In early spring the natural pull on the reserves are high and although the plants could photosynthesize, the net result would be a reduction of reserves. In summer the photosynthesis potential is low and any growth will have to come from reserves.

If you instead fertilize the lawn in fall following will happen:
- the grass re-starts active growth in september again when air temperatures become moderate and rain is more readily available. Since photosynthesis now also is possible, the grass will be able to put quite a bit away to storage eventhough growth is heavy. there is a net gain for the storage reserves.

- in late fall (late october) there is almost no active top growth. the grass has basically stopped growing due to unfavorable temperatures, but the grass plant metabolism is still active as long as the grass is still green and has not been put dormant by a deep heavy freeze. So from end october to about end november the ability to store carbohydrate reserves in the roots is highest. There is almost no demand for leaf tissue production and all photosynthesis taking place will be put in storage.

- next spring the grass will enter the season with a good well build storage reserve. The grass can photosynthesize at this time, but the early flush growth in spring will probably use all of the carbohydrates produced then plus some of the stored reserves. The balance is ok as long as you dont add a lot of fertilizer at this time.

- after the initial spring growth (april) you can fertilize to thicken up the lawn and give it a nice green color in may. The temperatures are still conductive for photosynthesis and the naturally slower growth (compared to march/april) combined with warmer soil temperatures makes this a good time to fertilize and still preserve storage reserves.

- if the lawn enters the summer with a healthy reserve of stored carbohydrates it will be able to maintain growth and avoid stress during hot summer  months.

Now compare this to a lawn which is fertilized in early spring (march) and then not again until middle of summer (july/august) which is typically how home owners fertilize lawns.

he very early spring fertilization will unduly reduce the reserves (early spring growth is already taxing on the reserves because plants will have to be constituted from the begining). It is better to wait until the first inital flush growth to fertilize.

If you fertilize in May, September and late October you will have a much healthier lawn.