# Spring fertilization of cool season grass in transition zone



## Virginiagal (Apr 24, 2017)

What is the best practice for fertilizing cool season grasses in the transition zone in the spring? What I've heard repeatedly is no fertilizer until late May or early June, then none during the summer. The reason given is it grows rapidly in the spring anyway, especially if you did a late fall fertilizer application, and nitrogen in the spring pushes shoot growth at the expense of the roots. The problem for the transition zone is our hot humid weather and it can be hot and humid in May and June and that's the time for brown patch to show up, which is exacerbated by nitrogen. So should we avoid nitrogen altogether? Or should we fertilize earlier?

I started checking university webpages (just ones in the transition zone) on fertilizing cool season turfgrasses. There are differing recommendations. Take a look at some of them (lb of nitrogen per 1000 square feet):

Virginia: 0-½ lb May (if using mostly WSN), 0-1 lb May 15-June 15 (if using mostly WIN)

North Carolina: 1 lb February, do not fertilize after March 15 until fall

South Carolina: same as North Carolina

Tennessee: ½ lb March 15, ½ lb April 15

Kentucky: ½ lb May/June only for very high maintenance lawns

Maryland: 0.5-0.9 lb late May if needed

Arkansas: April, none after May 1

Missouri: ½-1 lb April, none after May 1

Oklahoma: ½-1 lb March 1 (N only), ½-1 lb May 12 (NPK)

Mississippi: March 15 and April 15 (April can be skipped for TTTF)

Alabama: February, none after March 15

Though there is no consensus, it does seem that the more southern states are more adamant about not doing late spring fertilization. (A February application was interesting. North Carolina, South Carolina, and Alabama all recommended fertilizer in February in addition to fertilizer in November, the late fall application.)

I found an article by Richard Hull in Turfgrass Trends: "Managing Turfgrass for Maximum Root Growth." Here is the link:
https://www.google.com/url?sa=t&sou... humid summers?
(I posted this on Houzz too)


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## Redtenchu (Jan 28, 2017)

I have never grown a cool season lawn, but I found this to be a very interesting topic.

I like your recommendation/logic for using synthetic fertilizers during the cooler weather and organic (if you choose) during warmer weather. It makes perfect sense now that I've read it to myself. I may adopt this tactic for my Bermuda Grass.

Sorry, I don't have any input for you inquires.

Thank you for sharing this with us.


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## GrassDaddy (Mar 21, 2017)

Great question! I'm up north so I've got no real advice except to use slow release. I do know most of the nitrogen needed is in the fall and most people hit it in the spring because they want their lawn to green up faster.


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## j4c11 (Apr 30, 2017)

It really depends on your quality expectations, which determine your maintenance schedule. I see it like this:
*
HIGH MAINTENANCE*


1 lb fast N/thousand monthly March+April

0.75 lb slow N/thousand monthly May+June

0.35 oz trinexapac-ethyl/thousand every 2 weeks March through September

Fungicide at preventive rate/thousand every 2 weeks May through September

Foliar iron March-September for color

*NORMAL*

0.5 lb N May 1st

Fungicide at preventive rate/thousand every 2 weeks May through September

Foliar iron March-September for color

*LOW*

Nothing until September

I feel like deja-vu for some reason :mrgreen:


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## Virginiagal (Apr 24, 2017)

After much discussion on Houzz (which went off on tangents) this is where I am on this topic:

For well established grass, if you did a late season fertilization (fast release synthetic after grass stopped growing, before ground freezes), you likely don't need nitrogen in early spring. If you have well established tttf or fine fescue, you can likely skip nitrogen until early fall. However, if the grass shows signs of nitrogen deficiency, give it a very light application (¼-½ lb/k) of nitrogen (organic or synthetic, but probably synthetic since you will get a faster response to solve a problem) and see if that is enough. If not, do a little bit more. We are trying to solve the nitrogen deficiency with as little fertilizer as possible to prevent exacerbation of fungal problems in our hot, humid late spring and summer. Also in hot weather, fescue does not want to grow and we shouldn't force growth. Fescue needs 2-3 lb/k of nitrogen a year. Most should be in the fall, and all of it can be in the fall.

For well established KBG, the grass will need some nitrogen at some point in the spring. The general advice is to wait until the end of May or first of June when the spring growth spurt is slowing down. Fertilizer then will replenish nutrients. The problem with that advice in the transitional zone is fungus, as May/June is when fungal problems develop and nitrogen exacerbates them. The problem with early spring fertilizer is that it can promote excessive shoot growth at the expense of the roots. There is no really good time for it in the spring, so I propose a trickle all spring long. You get trickles with organic fertilizer or a low rate of a slow release synthetic. KBG needs 3-4 lb/k of nitrogen a year. Most should be in the fall.

Now for those with grass planted the previous fall, which will include most of us with tttf: the roots are small and can only take in small amounts of nutrients. The late fall fertilization, if we did it, left only a small reserve in the roots. We should fertilize in early spring, but only with small amounts. The roots are still small. So a trickle all spring would be good. I propose an organic feeding in early spring, ideally grains (Milorganite still has a fast release component). Or for those opposed to organic feeding, a low rate of slow release synthetic.

As for summer, only fertilize if necessary (nitrogen deficiency), with as little as possible.

As for what I will do for my tttf, if I have to overseed this fall (it seems to be necessary every year), I will do cracked corn or cornmeal in the spring, maybe 10 lb/k in March and 10 lb/k in May. If I don't​ have to overseed, no nitrogen in the spring or summer, unless I notice a deficiency.


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