There's so much more to a great yard than just mowing the lawn.

Which lawn fertilizer should you choose?

wpid-20150430_111659.jpgOnce your grass has turned and green and spring is here to stay, fertilizing will help your lawn take up needed nutrients. Smart fertilizing will help your lawn be green, thick, healthy, and drought-resistant this summer. If you have a lawn, you need to fertilize it.

Keep in mind there’s more to it than just fertilizer.

Fertilizer is only one of the four critical practices you need for a great lawn this summer. If you’re just starting out, check out my article on “Easy Steps to a Great Lawn.” The other three practices are core aerating, watering, and mowing.

What type of fertilizer should you buy?

In a nutshell, you need to buy a fertilizer that supplies the nutrients that your lawn needs, without any extra stuff you don’t need. Most lawns in Colorado need nitrogen. That’s about it. Talk about simple needs. Keep in mind that the nitrogen in a form that won’t feed it too quickly or too slowly.

So, when you’re standing in the garden center, how do you know which fertilizer contains nitrogen– and in the right form? Which bag should you buy? Let’s get straight to my recommendations:

Here are the good choices.

The fertilizers listed below fit the criteria I’ll explain later, plus they are generally available at many garden centers and nurseries along the Front Range. Undoubtedly, there are additional high quality fertilizers at your local garden center or nursery made by different manufacturers. Feel free to choose them once you figure out what’s in the bag. I put an Amazon link to the Scotts fertilizer just in case you’d like it shipped to you.

  • Richlawn Turf Food
  • Scotts Turf Builder
  • Sta-Green Lawn Fertilizer Plus Iron
  • Ace Hardware Brand Lawn Fertilizer
  • Scotts Snap Pac Lawn Fertilizer
  • Scotts Natural Lawn Fertilizer

No guarantee of availability or performance is implied. 

Here are pictures of the bags just in case you want to know you’re getting the right stuff. Notice the Sta-Green fertilizer has two different looks to their bags. I think one is last year’s and the other is this year’s design, but they appear to be the same product.

Richlawn Turf FoodScotts Turf Builder Lawn Food

Sta-Green Phosphorous-Free with Iron Lawn FertilizerSta-Green Lawn Fertilizer Plus IronScotts Snap Pac Lawn FertilizerScotts Natural Lawn Food

Ace Hardware Lawn FertilizerShouldn’t you buy a fertilizer with weed and feed?

Generally not. Avoid using lawn fertilizer with weed killer most of the time.

Here’s the problem with using weed and feed fertilizer every time you feed your grass:

All of your landscape plants that root into your lawn (which is all of them close to the lawn) will take up the weed killer through their roots. The weed killer in the fertilizer affects “broadleaf plants,” which includes most plants that are not a type of grass. Guess what? Your trees, shrubs, and flowers are all broadleaf plants.

The weed killer will weaken your trees, shrubs, and flowers over time, since the weed killer effects all non-grass plants. Especially avoid using weed and feed if you have a tree planted in or close to your lawn. Here’s an article that discusses this topic further.

Spot spray weeds in your lawn instead

Scotts Touch Up

You can use a bottle of weed killer for your lawn to spot spray weeds rather than using weed and feed fertilizer.

It’s a much better practice to use lawn fertilizer that does NOT contain weed killer. If you end up with weeds in your lawn, use a bottle of ready-to-use “lawn weed killer” to spray the individual weeds when you notice them. Since you’re applying just a little bit in a very small area, it’s much less likely that your landscape plants will take up the weed killer.

So I’m saying that you should NEVER use weed and feed? Well, if you have a terrible dandelion problem throughout your whole yard, it’s okay to use weed and feed once or twice to get the problem under control. Just don’t use it indefinitely after the weeds are under control. You definitely don’t need to use it every time you fertilize.

But shouldn’t you get a fertilizer with crabgrass preventer?

Only choose a fertilizer with crabgrass preventer if you have a problem with crabgrass. How do you know if you have a problem with crabgrass? Think back to last year. Did you notice grassy weeds that look like this? If you’re sure you’ve indeed got crabgrass, choosing a fertilizer with crabgrass preventer might be a good idea.

If you don’t recall having crabgrass in your lawn, choose a fertilizer that does not include crabgrass preventer. There’s no sense in adding extra chemicals to your landscape that you don’t need. Applying chemicals “just in case” is not good for the environment or you.

Here are two types of lawn fertilizer with crabgrass preventer you’re likely to see.

Sta-Green Lawn Ferilizer with Crabgrass PreventerScotts Turf Builder with Crabgrass Preventer

Crabgrass does not start growing in most Front Range communities until mid-May. It dies over the winter and grows from seed each summer once the soil has warmed up. If you have grassy weeds that are at least a couple inches tall in March or April, it’s likely you have a different grassy weed like orchardgrass, smooth brome or quackgrass. Crabgrass preventer won’t get rid of these weeds, so don’t bother applying it.

What about the three numbers on the bag?

N-P-K Label on Fertilizer Bag

The three numbers on the bag list the percent of nitrogen, phosphate and potash by weight.

The three numbers on the bag are not that important when choosing a fertilizer, so don’t let this slow you down. Most lawn fertilizers generally are formulated to contain mostly nitrogen, plus little to no phosphate or potash. This is exactly what your lawn needs.

Rather than determining which fertilizer to choose, the numbers on the bag will affect how much you should apply to your lawn. Generally, the rate to apply the fertilizer is described on the back of the bag. It’s based on what type of fertilizer spreader you have.

If there are two recommendations on the back of the bag, choose the lower rate so you’re putting less fertilizer on your lawn. Going this route will make sure you don’t burn your grass or cause it to grow too quickly. You can learn more about how much to apply here.

What about iron? 

Iron Rich by Richlawn

This lawn fertilizer contains iron. It’s okay to use.

Occasionally, lawns in Colorado will be deficient in iron. If you notice a persistent yellowing of your grass that doesn’t improve after you apply nitrogen fertilizer, it’s possible your lawn needs iron. So, it’s okay to choose a fertilizer that contains iron.

If, however, you’ve never had a problem with your lawn yellowing, skip the iron.


What about insect or grub control?

It’s really not necessary in Colorado. I very rarely find grubs are a problem in home lawns. Billbug damage doesn’t even show up until July or August, which is not the right time to fertilize. Deal with insects or grubs separately from fertilizing.

Here are some photos of lawn products that contain insect killers. These are not necessary to use in Colorado on a regular basis.

Scotts Turf Builder Summer GuardLawn Insect KillerSpectracide Insect Killer for Lawns





        What about how quickly the nitrogen is released from the fertilizer? 

It’s a good idea to stay away from fertilizers with only 100% quick release nutrients. Most quality lawn fertilizers on the market have a mixture of quick and slow release nutrients, which is best for your lawn. It helps your lawn grow slowly and steadily rather than growing quickly. If it grows too quickly, the tender, succulent growth will crash when hot weather arrives. Remember, the tortoise wins the race.

Here are some quick release fertilizers to avoid. Don’t buy these if the main label on the bag says the fertilizer contains ONLY any of the following: urea, ammonium nitrate, ammonium sulfate, potassium nitrate, or calcium nitrate. You’d most likely encounter these at a farm supply store or garden center and they’re usually significantly cheaper than the other lawn fertilizers on the shelf. Spend a little more this year to make sure you don’t feed your lawn too quickly.

When is the best time to fertilize?

May 1 to June 15 is a great time to do your spring fertilization in most Front Range communities. Don’t fertilize once the weather gets really warm. Avoid fertilizing your lawn in June, July, and August. It’s even better to fertilize your lawn in fall– once around Labor Day and again around Halloween.

What about fertilizing before May 1? It might be beneficial, or might not. Check out this post to read more.

How do you actually apply the fertilizer?

Great question. I’ve got an article on that topic here.

Okay, now you’re ready to go! Once again, check out my article on “Easy Steps to a Great Lawn” plus my articles on core aerating, watering, and mowingGet out there and fertilize, and you’ll be rewarded with a healthy, green lawn this summer.



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