Suggested Landscape Practices for HOAs and Their Landscape Contractors

Q. We need expert opinion soon about what  to use as fertilizer for Greenway grass, bushes, and trees. Your advice please.

Greenway grass:

A. What is the range of N-P-K in cow manure that some landscapers use for grass?

Not sure what you mean by a "greenway" grasss.... but....It's really not fair to compare cow manure to a fertilizer because it isn't. They are using it more as a top dressing than as a fertilizer application. Manures vary in fertilizer content but are generally about 4% nitrogen and usually low in phosphorus and potassium. You should not rely on cow manure as a fertilizer. The fertilizer should be applied separately from a cow manure. An inexpensive fertilizer for starting plants and getting root growth from seeds, seedlings or newly planted trees and shrubs is 16-20-0 or DAP (18-46-0).

 

B. What inorganic fertilizer would you recommend and the amount/acre?

For turfgrass you should never apply more than 1 pound of nitrogen every 1000 ft.² or 43 pounds of nitrogen per acre. In my opinion, this is excessive and should be closer to 1/2 pound of nitrogen per thousand square feet or 22 pounds of nitrogen per acre. This would be for inexpensive, quick release agricultural nitrogen fertilizers. If you are applying more expensive horticulture fertilizers that contains slow release nitrogen, then you can bump the application rate up and apply it less often. How much to bump it up depends on what percentage of the nitrogen is slow release in the fertilizer.  

 

The fertilizer you mention (10-10-10) has 10% nitrogen. It is not a good turfgrass fertilizer but it's fine for trees and shrubs. In fact, turfgrass fertilizers are fine for trees and shrubs as well. The best turfgrass fertilizers are in the ratio of 3-1-2 or 4-1-2. An example would be 21-7-14, is a 3-1-2 ratio fertilizer. To apply 1 pound of nitrogen with your 10-10-10 fertilizer requires 10 pounds of fertilizer. Using your 10-10-10 fertilizer you would apply 435 pounds of the fertilizer to get 43.5 pounds of applied nitrogen (there is 43,560 square feet in an acre or 43.5 thousands of square feet). Like I said, I think one pound of nitrogen per thousand square feet is excessive and you will not see the difference once you exceed three quarters of a pound of nitrogen per thousand square feet or about 33 pounds of nitrogen per acre. In fact, if you apply 1 pound of nitrogen per thousand square feet it will push turfgrass growth quite rapidly and cause alot of mowing during cool weather. Do you really want that?

 

Negotiate. If you use only half the fertilizer (1/2 pound per thousand instead of one pound per thousand) then use a better fertilizer at half the rate. Cost of the fertilizer is the same or better.

C. How many times per year and which month(s)?

For tall fescue turfgrass I would apply nitrogen four times a year; Labor Day, Memorial Day, Fourth of July and Thanksgiving. During the hot summer months I would always make sure you do not exceed 1/2 pound of nitrogen per thousand square feet or you could end up with some burning if people are not careful. If you are using mulching mowers you can skip the Fourth of July application. If you are using mulching mowers you should never exceed 1/2 pound of nitrogen per thousand square feet in a single application.

 

D. Should a roller of punchers be used immediately after fertilizing?

I assume you mean aeration. Core aeration can be done any time of the year and does not really relate to a fertilizer application. The only exception might be when you are applying a high phosphorus fertilizer

 

E. Should organic fertilizer (cow manure) even be used to fertilize grass?

Cow manure is not a fertilizer. Fertilizers will have the amount of N-P-K listed on the bad as required by state law.

Bushes:

A. What inorganic fertilizer (N-P-K) would you recommend and the amount/bush?

Turfgrass fertilizers in the ratio I mention above are good for most trees and shrubs. You would apply this fertilizer in the very early spring or late winter. The amount to apply is similar to the amount you would apply to turfgrass but is calculated under the canopy area of trees and shrubs. A small tree that occupies 100 ft.² of canopy space would get 1/10 of a pound of nitrogen. A tree that had 1000 ft.² under its canopy would get 1 pound of nitrogen. The driver of growth for trees, shrubs and turfgrass is nitrogen.

B. Applied dry, or liquid, in the gravel around bushes?

Dry fertilizers are applied near the irrigation source. If trees and shrubs are irrigated by sprinklers, then you distribute the fertilizer so that the sprinklers pushed the water into the rootzone. If these are drip irrigated, it is applied in the soil next to the drip emitters and the water carries a fertilizer into the rootzone. If you are applying a liquid fertilizer to the foliage obviously you have to wait for the foliage to appear in the spring to make an application. If this is a liquid fertilizer applied to the soil and make the application close to the drip emitters within a few inches under the mulch or under the turfgrass. Never apply a fertilizer to trees and shrubs deeper than about six or 8 inches. Fertilizer spikes are convenient but expensive. Liquid applications to the foliage last about 4 to 8 weeks. Dry fertilizers applied to the soil last longer if that's important.

C. How many times per year and which month(s)?

Most trees and shrubs will require a single application of a fertilizer to the soil during the months of December through about March. In a pinch you could go as late as April. Some plants tend to get yellow due to iron chlorosis or a lack of available iron. Usually a single application of an iron fertilizer that contains the chelate EDDHA is enough to keep them from yellowing. If these plants have been yellowing and are in poor condition for several years, this will probably not work in correcting a severe problem. The iron fertilizer should be applied at the same time as the other fertilizers, in early spring or late winter.

Tall trees:

A. What inorganic fertilizer (N-P-K) would you recommend and the amount/tree?

You can use a good turfgrass fertilizer for most tall trees and shrubs. To be effective this fertilizer should be applied close to a source of water for the trees so that it is washed into the rootzone. It should not be applied deeper than 6 to 8 inches in the soil. Other fertilizers in ratios like 1-1-1 are also okay but the high phosphorus of the middle number is really not needed unless these are flowering trees.

B. Applied dry, or liquid, near the end of branches around trees?

Fertilizer is fertilizer whether it is applied dry or liquid. The amount of nitrogen applied per tree is what is critical. Liquid fertilizers applied to the foliage or short lived. Dry or liquid fertilizers applied to the soil last longer.

C. How many times per year and which month(s)?

Once per year is enough in the very early spring just before new growth or not long after it begins.