It's really based on what is in your soil and what your soil needs. Where I live, the soils tend to be naturally high in P and K, so the correct numbers will always be N-0-0. The N number would basically be used to determine how much fertilizer to spread. Many people here spend more money to buy fertilizers with P and K, but they are wasting money when they do that.

The proper numbers where you are would depend on what nutrients your soil needs.

In lieu of a soil test use either a 3-1-2 or 4-1-2 ratio. Like 15-5-10 or 20-5-10. Lesco has them.

One more vote for what BP said. Get a soil test and don't add anything that it doesn't tell you need.

BP - read what I sent you in email - you could have written it!!

Andy--I didn't get an email from you. Did you send it from the member page here?

So the right primary nutrients number depends on the soil test, right? Is the soil test easy? In addition, can we say the general rule is to try selecting the high N but lower P and K numbers because "bpgreen" said "Many people here spend more money to buy fertilizers with P and K, but they are wasting money when they do that".

I don't think there's a rule of thumb driven by anything like temperature, season, etc. Texasweed is the Bermuda guru, so his advice is probably the closest you can come to a general rule of thumb without a soil test.

A soil test is pretty easy and not too expensive. You can contact the extension office at your local state university and they will send you what you need, along with instructions on how to gather the soil and send it back. They usually charge somewhere in the neighborhood of $10-$20 for the tests.

When I said many people here, I meant here geographically, not here on this forum. Along the Wasatch front, there is plenty of P and K in the soil and adding more won't help and can actually hurt (on top of costing more). Where you are, things could be completely different.

Since the soil test needs to be handled by the professional or agency, I do not think most of people will have the soil tested before buy the lawn care product. Only the lawn care professional may be interested in reading the primary nutrients numbers, but most of people just ignore it when purchase the lawn product. Is it right?

"Since the soil test needs to be handled by the professional or agency, I do not think most of people will have the soil tested before buy the lawn care product. Only the lawn care professional may be interested in reading the primary nutrients numbers, but most of people just ignore it when purchase the lawn product. Is it right?"

I guess that depends on what you mean by right. If you are asking if you're correct in assuming that many homeowners don't get soil tests and add what they should be adding and instead just pick up the first bag they see, you may be right.

If you are asking if that is the right thing to do to get the healthiest lawn you can, then I think the answer is no.

Back before I learned about organic lawn care, I used to buy whatever was piled up in front of the hardware store. I think a lot of people do that. If you really start to fine tune your soil's needs to a chemical ratio, you are going to spend more seasons NOT fertilizing the lawn than fertilizing it.

Once I went to an organic program, I quit worrying about any of that stuff. If my lawn does not continue to be dark green until the next federal holiday, I use more of it next time. You can get away with this approach on an organic plan but not if you are using chemical fertilizers. Basically I'm lazy about it. I just don't have time for questionable soil tests, questionable interpretation of test results, timing of the tests, and then finding all the fertilizer was sold out two weeks ago. And in the end I was still going to buy the bag on the sidewalk out in front of the hardware store. Now I use corn meal on the federal holidays and forget about all the chemistry hassle.

I try to know the general or safe rule to pick a right primary nutrients number for the lawn care. Most of people probably will not do the soil test before buy the bag. However, almost of every bag has the xx-x-xx number there. I have to think which one may be the right or safe primary nutrients number? For example, should 19-0-7 be better than 18-0-9? What effect will be on the grass by selection of different primary nutrients number? Does anyone have experience in the selection of the primary nutrients number without soil tested or you never care the xx-x-xx on the lawn care bag but only what it can do such as Crabgrass Pre-emergent Fertilizer, Weed & Feed or with 2% iron etc?

You're making a mountain out of a mole hill thinking like this -

>For example, should 19-0-7 be better than 18-0-9?

and here's why!

The spreader setting for the 19-0-7 might be, oh let's just say #4.5 - And the setting for the 18-0-9 might be # 4.25

Using either product - the goal of those settings is to attempt to apply 1 pound of nitrogen per 1000 sq. ft. !!!!

Even if you bought 33-0-12, you still would be applying 1 pound of nitrogen per 1000 sq. ft. if you follow the recommended setting for your spreader. So there isn't any better primary nutrients with this bag V's that bag of fertilizer.

If you lawn needs nitrogen, buy a bag with a high first number. If you need phosphorous or potash, buy a bag with higher corresponding numbers ... buy according to needs. Which nutrients do you need? A soil test will tell you.

This link explains the nutrients. Click below

Here is a link that might be useful: Nutrients explained

I fertilize with coffee grounds from Starbucks now, but when I was using synthetic fertilizers, I used fertilizers with numbers like 21-0-0, 39-0-0 or 46-0-0. I know that the soil around here is high in P and K (and high pH) and don't need a soil test to tell me that.

You've had one answer that gave a rule of thumb that could be used in lieu of a soil test from Texas Weed:

"In lieu of a soil test use either a 3-1-2 or 4-1-2 ratio. Like 15-5-10 or 20-5-10. Lesco has them."

I think that applies to the first and last fertilization of the year. Acccording to TW's Bermuda Bible, other fertilizations should be N-0-0.

One thing to note is that N is relatively stable and the others are fairly stable. If you mulch mow, you'll need to continue adding N because some of it is lost to the atmosphere, but the P and K stick around, so if you add them every year and mulch mow, they'll build up in the soil and you could end up with too much.

I think the bottom line is that if you want to get what you need, the only way to know for sure is to get a soil test. If you're using an organic approach, you're probably not buying bags with N-P-K numbers on them anyway. If you just want to buy something and put it down, use something with a 3-1-2 or 4-1-2 for the first and last and N-0-0 for others.

I used to use whatever was at hand. I now use coffee grounds, but if I used synthetics where I live now, I'd never use anything with P or K. If I move in the future, if coffee grounds aren't practical (it takes a lot to get enough nitrogen for a lawn), I wouldn't use any fertilizer with P or K unless a soil test indicated I needed them.

That is what I would do and that's what I would advise you to do. If your extension service does soil testing, it's usually pretty cheap and it's not something that should only be done by pros. If you don't want to get a soil test, use TW's approach.

I decided to get one bag from the Home Depot do the first time lawn maintenance but I only saw Lesco Crabgrass Pre-emergent Plus Fertilizer 19-0-7, Crabgrass Pre-emergent Plus Potash 0-0-7 and Weed & Feed 18-0-9. The 3-1-2 or 4-1-2 ratio do not apply. My lawn has lots of weeds and I rarely water the grass in summer. What primary nutrients number or bag should I select?

some areas have started banning fertilizers containing P (the middle number). That might be the case where you are. Since none of them have P, you can use the 3-x-2 or 4-x-2 ratio, which makes the 18-0-9 the closest. I don't really like weed and feed products. I think it's better to fertilize in one step and kill the weeds in another (usually a week or so later when they're going strong from the fertilizer).

It's probably too late for crabgrass prevention in GA, so the pre emergent won't help.

If those are your only options, I guess I'd go with the 18-0-9.

> My lawn has lots of weeds and I rarely water the grass in summer.

Then why pray tell are you talking about fertilizer?

My lawn has lots of weeds and I rarely water the grass in summer.

I agree with Gary. Unless and until you have your watering and mowing working for you, you will have weeds, weeds, and more weeds. Fertilizer should be near the bottom of the list of your worries.

Do you mind starting over?

Where do you live?
What kind of grass do you have?
What kind of weeds do you have?
What is the lawn used for (children, pets, just looking at)?
Are you willing to water in the summer?
How often do you mow and how high??
Is the lawn shaded?

With all do respect, I see a lot of false information being spread around. Because a soil test says "You have Phosphorus and Potassium" doesn't mean you need to avoid it. A soil test doesn't tell you much, except exactly what it sounds like. The nutrients in the soil. This doesn't tell you what's available to the turf-grass. You may have to spend more, but a tissue test will tell you what you need.

I often hear that quite often around here, in Central Texas. Our soil has too much Phos. and Potassium, blah, blah, blah. We don't need it. But from someone that has taken tissue test on 100+ yards, I often have to refrain myself. Are you sure about that? Do you see that line right at the to with your pH? Do you see the tissue test? I hate to break it to you, but often enough, none of the phosphorus in the soil is available. And much of the potassium is binded in the soil? I never had such great luck until I ignored the soil test, went with tissue test, and started spoon feeding monthly applications of Potassium (just in a more available form), despite what our soil test read. Potassium is a big must and the reality is, most of it here is either bound to the organic matter in the soil, and the little bit that is usable is getting consumed by the turf quicker then you give it.

In this situation, .50 of potassium fed monthly will suffice the turfs needs. I prefer either Potassium Nitrate if the pH is low, and Potassium Sulfate if the pH is high. This is in available form and will be used up by the turf-grass.

BP Green, I'm wondering if your in the Austin area, considering you speak like someone from my area (Austin) does. That says, "high pH, high phosphorus and potassium." Just to give you a hint of advice with your high pH. Read my above post. Also, with your high pH, often your soil test will lack sulfur and you will have limited iron, which is what gets your turf dark green.

On high pH soils I suggest a monthly dose of powder Chleated Iron, Potassium Sulfate, and 1 lb. of Citric Acid per 1,000, sprayed on a monthly basis. You can also use Iron Sulfate to aid in the pH combined with Ammonia Sulfate as your nitrogen source, but this will tear spray pumps up fast as it's like sandblasting the inside of your equipment. The first suggestion is much better. And I suggest either "Main Event" or FeAture 6-0-0 by loveland products with additional micronutrients. That's how you keep grass green without over-dosing it on Nitrogen and promoting disease and stress on the lawn through the summer.

Turf Doc, I'll give you a brief rundown of the players on this thread

bpgreen has a native prairie grass lawn in the Salt Lake City area. He is active on other forums but a lot of these players have been chased away by the forum's previous owner(s).

TexasWeed was a sod farmer north of Dallas. You indicated on another post that you knew who he was. Now he's retired from that biz and is a greens keeper in Prescott, AZ. He's off all the forums.

Andy has a poa plantation mixed with KBG and possibly fescue in New York somewhere. He reads soil tests on another forum and occasionally pops up here.

dchall_san_antonio: I'm in and about San Antonio. I was in George West for a couple years and have been in Bandera, now, for about 18 months. My daughter's at Southwestern in Georgetown and my training hq is in Round Rock so don't be surprised if I look you up and stop in for a visit.

compiler: We never did find out anything about him/her. It's important to know where the people live to give any good advice. I think the assumption was made that the OP had bermuda. Don't know why that was assumed, so I asked the questions.

Sure, tissue sample testing would be nice. You really should correlate the plant uptake with the soil chemistry, but that's fairly impractical at this point. It took some considerable time and effort to locate Logan Labs in Ohio for high quality, reliable soil testing. Even the Texas Plant and Soil Lab did not make it through the ad hoc test of the testing labs, and those guys are geniuses with plants and soils. The $25 test from Logan Labs is considerably more and better than the old $35 test at TPSL back when K was alive. Now that K's passed on the new management has fragmented the tests so it would cost $60 or more to get what Logan Labs gives, and the TPSL explanations are less informative.

I wasn't going to reply to the doctor, but since David replied, I'll point out that this is necroposting.

Before the doctor chimed in, this thread was almost 7 years old. The advice I give now is different from the advice I gave then.

I'm not sure why the doctor would think I'm from Austin since UT is in my profile and I referred to being in the Wasatch front in one of my posts.

I will say that I get a kick out of the "with all do respect" comment for a couple of reasons. The first is that it should be "with all due respect" and the second is that almost invariably, what follows "with all due respect" (or in this case "do") is never something that is with all due respect. Kind of like how "not to be pedantic, but " is always followed by something pedantic.

Speaking of pedantic, I think that if you want people to look on you as a "doctor" it would help if you'd learn the difference between "your" and "you're"

And using chelated iron on a lawn? Seriously? For soils with high pH, EDTA chalets aren't going to be much help. Foliar iron application will work (when it's cool enough), but for foliar application, chelated iron isn't needed.

I need EDDHA chelated iron to get my maple tree to respond. It's much cheaper (and longer term) to drill holes in the ground and add sulfur (sorry, but surface applied sulfur doesn't work here). I don't bother trying to change the iron availability for my lawn. Instead, I plant grasses that don't need low pH soil to thrive.

Hey, bp. UT is completely unambiguous to a Texan. It refers to only one thing - University of Texas. Knowing you for so long I only see Utah in your handle, but when I put on my boots, UT is that big, orange school in Austin.

I'm not sure Turf Doctor's advice is practical for home owners, but I'm interested in what he has to say. Remember when the application of Cascade Plus surfactant wasn't practical for anyone short of a professional sports complex? And now we're spraying shampoo to get the same effect.

This particular thread is a hard one to come back to since we never knew anything about the OP's lawn or soil. He might have been growing centipede in FL where the grass grows fine with no fertilizer at all.

I'd first like to apologize to the Turf Doctor for making snarky comments about grammar mistakes. I can be a git of a grammar nazi, but I try to restrain myself, especially since I know a lot of mistakes are introduced by autocorrect.

Interesting point about UT in Texas. That would explain Austin, I guess. I think there are a bunch of UT campuses, but UT Austin is biggest? I guess that's kind of like some people in the east who use NE to mean either NorthEast or New England, confusing people from the midwest and west, who think they're talking about Nebraska.