Can I fertilize grass around trees

[whitenack]

I have been struggling with getting a previously abused lawn up to a healthy level.

I have sent off some soil tests, which I am still waiting for responses.

I assume the recommendation from the tests will be to add fertilizer or some other agent to the lawn.

In this same yard, I planted two young ginkgo trees last year, and there is an existing dogwood, two older maples, and two older redbuds.

Will fertilizer hurt my trees?

 

[sawyerDave]

Fertilizer

Unless you over fertilize, no, you will not hurt your trees. Follow the directions on the bag of fertilizer and remember you can always fertilize light and do it again, but its darn near impossible to pick it up again! One other thing don't use weed and feed products containing 2,4-d ester, or dicamba under trees. They can damage trees.:bang: :bang:

 

[eagleknight97]

Fertilizer will not only NOT hurt your trees, but it will help them more than likely. Fertilizing your trees ideally would have you drilling foot and a half deep holes radially out from your tree starting at 3 ft from the trunk out to half the diameter of the crown past the drip line.

 

[Kneejerk Bombas]

On most information sheets turned in with soil samples, they ask what crop you are growing. You should have indicated turf and landscape plants.
Growing turf and trees have similar nutritional needs, except to get lush thick turf, you'll use a lot more nitrogen than you want for mature trees.
For those who want to add nitrogen to mature trees, I would suggest you use it at a rate of about 1 pound per 1000 square feet, per year, unless soil tests indicate an extreme deficiency.

 

[osb_mail]

Hey good pick on the ginkgos I am sure you will enjoy them for a long time . I would put a good layer of mulch around tree try to keep your grass away from trees . They really dont like each other also A little lawn fret wont hurt just take in consideration your lawn fret. If you plan on fertilizing your trees .

 

[rebelman]

Seems to me fertilizer can spur too quick growth on trees. Then they fold over. They may get yellowing leaves or thick sucker growth. Mulch is much more important if you want your tree to be healthy. Like OSB says. The importance of mulch is poorly understood and under rated. I would think large mulch areas would add feature and value to you lawn also. Lot's of other reasons too.

 

[eagleknight97]

Seems to me fertilizer can spur too quick growth on trees. Then they fold over. They may get yellowing leaves or thick sucker growth. Mulch is much more important if you want your tree to be healthy. Like OSB says. The importance of mulch is poorly understood and under rated. I would think large mulch areas would add feature and value to you lawn also. Lot's of other reasons too.

Why would fertilizing trees cause yellowing of leaves or sucker growth?

 

[rebelman]

I believe fertilizing grass heavily around trees can "burn" leaves. I have also seen trees that recieve fertilizer runoff that seem to grow abnormally fast. These don't seem to be very strong. I don't think that proper fertilization of the tree is a problem, it is heavy fertilization of grass in the root zone.

 

[bigtreeguy]

Excessive nitrogen causes a flush of growth to trees at the expense of the roots and disease fighting abilities...especially in newly established trees....Mulch is the way to go.... 2-4" deep is plenty.

 

[treeseer]

Fertilizing your trees ideally would have you drilling foot and a half deep holes radially out from your tree starting at 3 ft from the trunk out to half the diameter of the crown past the drip line.

OK the area covered sounds OK, but 2 questions:

1. Doesn't drilling cut roots?

2. How many roots exist 18" below the surface?

3. (ok I lied) How much fert and what else would you put in the holes?

 

[eagleknight97]

OK the area covered sounds OK, but 2 questions:

1. Doesn't drilling cut roots?

2. How many roots exist 18" below the surface?

3. (ok I lied) How much fert and what else would you put in the holes?

1) Drilling does cut roots but you would be using a soil auger rather than an actual drill bit which makes it more likely youll be going around big roots than through them. The spead pattern isnt law, you can move around slightly so youre not trying to go right through large roots.

2) Not many roots exist below 18" from the surface which is why you go down to 18" and not really any further.

3) Typically you would want to apply approximately 5lbs of actual Nitrogen per 1000sqft of root area. However, you dont want to do this every year. Every 3-5 years of specific tree fertilization is good. If you fertilize your lawn normally, the excess nitrogen will leach through and provide some for the tree. As far as what else you would place in these holes, thats where you can get creative and really help out the tree and the soil around it. You can add peat, compost, top soil, sand, vermiculite, etc etc. Basically its a chance for you to amend the soil surrounding the tree. If you got poor drainage, add some sandy amendment or vermiculite. If you want to increase the OM of the soil, add some peat or compost. Whatever you want/need.

Drilling the fertilizer holes are also great ways to help aerate the soil. If you simply drilled the holes and added nothing to them, the aeration alone would help the trees growth out.

 

[eagleknight97]

Excessive nitrogen causes a flush of growth to trees at the expense of the roots and disease fighting abilities...especially in newly established trees....Mulch is the way to go.... 2-4" deep is plenty.

Doing this to newly established trees is not a good idea as you said, a little too much top growth and not enough root growth, messes up the whole root shoot ratio. Also, if the area around a newly established tree is too rich in nutrients, the roots will never grow out past that nutrient rich area and then when that soil is depleted, the tree is suddenly out of nutrients and doesnt have roots far enough out to get it from anywhere else.

 

[treeseer]

well it sounds like they do teach something useful at U of I; imagine that.

you have deep glacial/praire soils there so maybe augering 18" works. In our hard clay 12" is plenty. Augering glazes the hole so lateral spread is minimal. There is lots of research on this.

I don't understand the difference between a drill and an auger.

 

[Kneejerk Bombas]

1) Drilling does cut roots but you would be using a soil auger rather than an actual drill bit which makes it more likely youll be going around big roots than through them. The spead pattern isnt law, you can move around slightly so youre not trying to go right through large roots.

2) Not many roots exist below 18" from the surface which is why you go down to 18" and not really any further.

3) Typically you would want to apply approximately 5lbs of actual Nitrogen per 1000sqft of root area. However, you dont want to do this every year. Every 3-5 years of specific tree fertilization is good. If you fertilize your lawn normally, the excess nitrogen will leach through and provide some for the tree. As far as what else you would place in these holes, thats where you can get creative and really help out the tree and the soil around it. You can add peat, compost, top soil, sand, vermiculite, etc etc. Basically its a chance for you to amend the soil surrounding the tree. If you got poor drainage, add some sandy amendment or vermiculite. If you want to increase the OM of the soil, add some peat or compost. Whatever you want/need.

Drilling the fertilizer holes are also great ways to help aerate the soil. If you simply drilled the holes and added nothing to them, the aeration alone would help the trees growth out.

This advice defies everything I've come to know about tree fertilizing.

There are a few points that are good, like the deep holes filled with a dose of nitrogen that is too high even for turf, is applied in a way that few, if any tree roots will get it. The holes drilled down to the loose sub soils will create a pipeline directly into the water table, polluting that with the nitrates, rather than overdosing the tree.

 

[osb_mail]

I was thinking that people probably have better luck just plug aerate around trees like they do when they fret lawns .I would think that you would still get compaction on side of the plugs but not on bottom . It would also not be as damaging to tree roots .You would not have to clean up as much as drilling holes .The fret would only 2 to 3 inches deep instead of 12 to 18 inches . I think the ISA CA study book says not to use this method but I think it would be worth looking in to if you didnt want to drill holes or just surface apply . You could plug aerate your drip line and past then surface apply fret. anybody try ed this before .

 

[treespec]

Fert. vs Vertical mulching

With newly planted trees, don't fert. for as least 8-12 months. Simple rule of thumb, after waiting period, is 1" in diameter ='s 1lb. of fert. for 5" diameter and over. 1/2 lb. under 5". Apply amount halfway from base of tree, to dripline. Use broadcast method (speader). Also bear in mind, that approx. 50% of the fert. will be absorbed by turf surrounding, before it reaches tree roots. That's why fertilizing 4x's a year with proper Nit., Phos., & Potash is usally recommended the 1st 4-5 years. Verical mulching, on the other hand, is usally performed on older mature trees. A 3-4" dia. auger bit drilled approx. 6-8" deep, is used to remove the soil. The holes are refilled with mixed soil of combined with fert., or mulch soil mixture, or you can mix mycorrhizal products within the mix. Go to planthealthcare.com to learn about mycorrhizal products. Also excellent article in the Dec. '06 p.14 of Arborage.

 

[eagleknight97]

With newly planted trees, don't fert. for as least 8-12 months. Simple rule of thumb, after waiting period, is 1" in diameter ='s 1lb. of fert. for 5" diameter and over. 1/2 lb. under 5". Apply amount halfway from base of tree, to dripline. Use broadcast method (speader). Also bear in mind, that approx. 50% of the fert. will be absorbed by turf surrounding, before it reaches tree roots. That's why fertilizing 4x's a year with proper Nit., Phos., & Potash is usally recommended the 1st 4-5 years. Verical mulching, on the other hand, is usally performed on older mature trees. A 3-4" dia. auger bit drilled approx. 6-8" deep, is used to remove the soil. The holes are refilled with mixed soil of combined with fert., or mulch soil mixture, or you can mix mycorrhizal products within the mix. Go to planthealthcare.com to learn about mycorrhizal products. Also excellent article in the Dec. '06 p.14 of Arborage.

Why would you only go to the dripline? There are large amounts of roots that extend well past the dripline of a tree.

 

[kevinj]

There's a few trees out of sight from the firepit,
That some of the guys add urea (nitrogen) to.
Does that count ?
:fart:

 

[treespec]

I assume we were talking about newly planted trees. So your not going to have high volume of root growth beyond the dripline. Older trees, yes. I like apply fert. 10-15' past the dripline.

 

[eagleknight97]

I assume we were talking about newly planted trees. So your not going to have high volume of root growth beyond the dripline. Older trees, yes. I like apply fert. 10-15' past the dripline.

Ahh, thought you meant on older trees. Sorry bout that