Categories
Horticulture

Time to Fertilize Warm-Season Grasses 

June is the time to fertilize warm-season lawn grasses such as bermudagrass, buffalograss, and zoysiagrass. These species all thrive in warmer summer weather, so this is the time they respond best to fertilization. The most important nutrient is nitrogen (N), and these three species need it in varying amounts.
Bermudagrass requires the most nitrogen. High-quality bermuda stands need about 4 lbs. nitrogen per 1,000 sq. ft. during the season (low maintenance areas can get by on 2 lbs.). Apply this as four separate applications, about 4 weeks apart, of 1 lb. N per 1,000 sq. ft. starting in early May. It is already too late for the May application, but the June application is just around the corner. The nitrogen can come from either a quick- or slow-release source. So any lawn fertilizer will work. Plan the last application for no later than August 15. This helps ensure the bermudagrass is not overstimulated, making it susceptible to winter-kill.
Zoysiagrass grows more slowly than bermudagrass and is prone to develop thatch.
Consequently, it does not need as much nitrogen. In fact, too much is worse than too little. One
and one-half to 2 pounds N per 1,000 sq. ft. during the season is sufficient. Split the total in two
and apply once in early June and again around mid-July. Slow-release nitrogen is preferable but
quick-release is acceptable. Slow-release nitrogen is sometimes listed as “slowly available” or
“water insoluble.”
Buffalograss requires the least nitrogen of all lawn species commonly grown in Kansas. It will survive and persist with no supplemental nitrogen, but giving it 1 lb. N per 1,000 sq. ft. will
improve color and density. This application should be made in early June. For a little darker
color, fertilize it as described for zoysiagrass in the previous paragraph, but do not apply more
than a total of 2 lb. N per 1,000 sq. ft. in one season. Buffalograss tends to get weedy when given
too much nitrogen. As with zoysia, slow-release nitrogen is preferable, but fast-release is also
OK. As for all turfgrasses, phosphorus and potassium are best applied according to soil test
results because many soils already have adequate amounts of these nutrients for turfgrass
growth. If you need to apply phosphorus or potassium, it is best to core aerate beforehand to
ensure the nutrients reach the roots. (Ward Upham)

Categories
Horticulture

Don´t over apply phosphorous or potassium!

By: Scott Eckert, County Extension Agent, Horticulture

 

Plants need nutrients to live and grow.  Nitrogen is the nutrient needed most because it is used faster than any other.  Phosphorus and potassium are also needed but not as much as nitrogen.  In most soil test recommendations I make, the phosphorus and potassium readings are high or too high.   In fact, applying phosphorus and potassium when not needed will cause a buildup of these nutrients.

 

I have seen soil test measurements so high in phosphorus that it isn´t needed for the next 20 years.  Excessive soil phosphorus reduces the plant´s ability to take up required

micro-nutrients, particularly iron and zinc, even when soil tests show there are adequate

amounts of those nutrients in the soil.

 

Excess potassium causes nitrogen deficiency in plants and may affect the uptake of other positive ions such as Mg and Ca

 

What do these major nutrients do?

 

N (Nitrogen)-This nutrient element provides dark green color in plants. It promotes rapid vegetative growth. Plants deficient in nitrogen have thin, spindly stems, pale or yellow

foliage, and smaller than normal leaves.

 

P (Phosphorus)-This nutrient promotes early root formation, gives plants a rapid,

vigorous start, and hastens blooming and maturity. Plants deficient in this element

have thin, shortened stems, and leaves often develop a purplish color.

 

K (Potassium)-Potassium or potash hastens ripening of fruit. Plant disease re-sistance as well as general plant health de-pend on this element. It is also important in developing plump, full seeds. Plants deficient in this element have graying or browning on the outer edges of older leaves.

 

The content of N, P, and K is specified on bags of chemical fertilizers. The analysis or grade refers to the percent by weight of nitrogen, phosphate, and potash in that order. Thus, a 10-10-10 fertilizer contains 10 percent nitrogen (N), 10 percent phosphate (P205) and

10 percent potash (K20).