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How to Apply Fall Pre-Emergents with Fall Fertilizers

By DoMyOwn staff

Get a healthy lawn leading into winter by feeding your fall lawn correctly! Using pre-emergents with fertilizers will depend on grass type, soil temperatures, nutrient ratio, and more.

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Video Transcript

Hey guys it's Amber here at DoMyOwn and today we're going to talk about some fall and winter lawn prep and focus on some fertilizers and what you can do to use those with some pre-emergents that you may be looking to put down this time of year and what you need to do to really get your lawn ready for the winter and next spring. 

Soil testing is going to be a really important step to make sure that you're putting down the right fertilizers to benefit you when you do your applications so let's go ahead and get that soil test done get those results back and then we can analyze what's going to be best for your lawn and get the best application for your money.

So let's start out with cool season grasses. These are going to be types like fescue, bluegrass, and rye. You're not going to be able to put a pre-emergent down at the same time as aeration and overseeding because it will inhibit your new grass seed and we want to make sure that that turf comes up nice and healthy and doesn't have any barriers in its way. You can fertilize, however, whether it's at seeding or a few weeks after to really help that new grass seed build a good root system to get it ready for the winter months. For a lot of cool season lawns in these northern regions, you're going to want to pay attention to your soil temperatures because you're going to start cooling off a lot faster than some of these southern states would. You want to make sure that you're looking for fertilizers that really are going to benefit you but not putting them down too late in the season to where they're not going to be absorbed because your grass has already started kind of going dormant even though it technically "grows" during the winter. If you've done an aeration and overseeding, like we mentioned before, you're looking for something like a starter fertilizer. They're going to be geared towards that root development and a little bit of nitrogen and potassium just to make it a little more balanced fertilizer but without having too much to worry about during your application. If you're going to put those fertilizers down on the cool season grasses, you're not over applying and you're following those label instructions because you don't want to have too much of it left in the soil to where you'd have to worry about brown patch or winter die back occurring from too much of those nutrients in the soil.

Warm season grasses like bermuda, St. augustine, and centipede are going to be ones that thrive during the hottest months of the year. These are also going to be ones that you're going to fertilize during those times. You can use pre-emergents in the spring and the fall on these grasses. Normally, you're going to still keep in mind that if you do need to put some seed or sod down for things like st augustine that you don't use a pre-emergent until that turf has had a good chance to establish. We don't want to do anything to keep that grass from looking nice and healthy and really growing in your yard the way you want it to. You're not going to need a lot of fertilizers in the fall for warm season turfs because they're going to be going dormant. For the fertilizer application, you can always do it later on if needed or even do a follow-up application if you feel like your lawn needs another one going into the winter.

The numbers that you'll notice on fertilizer bags are going to come in three different sets: you've got nitrogen as your first number, phosphorus as your second, and potassium as your third. During the growing season and when the one is fully active and the soil temperatures are higher, nitrogen can be one of your best friends, especially on things like bermuda. It's going to really help that upward growth and you see the results that you're looking for. We don't want to put nitrogen down too late in the season, because you don't want to have so much of it built up in the lawn or potentially lead to burn, so let's try to focus those higher nitrogen applications and fertilizers on the market closer to your August and September months and really start weaning off and focusing more on those potassium applications as we lead into the later months of fall. The same thing can apply with cool season grasses, but keep in mind that as soil temperatures start to get lower, you're going to have that lawn only pick up the nutrients really as it needs it because it's still going to be working at a minimal capacity as the cold and winter months hit and any snow that may come on the ground on top of the turf. There's not a lot of need to overly apply nitrogen even on cool season grasses during that time.

So if you're looking to help your new lawn take root and establish a little bit faster...maybe you've got some erosion issues going on and you need those roots to be built up a little bit quicker or you're just trying to get the lawn to have a better stand in general, phosphorus can really be a great tool. This is used a lot more in cool season lawns around the fall because a lot of people are looking for good root development, which is what phosphorus really promotes.

For people who are having grasses like bermuda and others that will go dormant going into the fall and winter, potassium is really going to be the main nutrient that you might would focus on, less so on the phosphorus and the nitrogen. The potassium can give just an all-around boost to the yard to really make sure that we have no issues going into the winter and it's just got a good healthy stand and prepped for that colder weather.

There's liquid fertilizers there's liquid pre-emergent and most of the time those two products can be put together in the tank and applied at the same time. You're checking both labels for compatibility and if you need to do what's called a tank mix test in a small jar first to make sure there's no clumping or discoloring and that everything is going to be a-okay when you get ready to apply it to your lawn. There's also granular pre-emergents and granular fertilizers. You can only put these down in your spreader at the same time if they both are applied at the same amount of product per thousand square feet. If they're not compatible, you need to do two separate applications but it doesn't matter what order you do them in you can do them back to back it's going to be completely safe on the lawn.

A lot of you may be doing split pre-emergent applications. You can also treat your fertilizers the same way if you want to do a split application at the same time. Use the same rate during both applications and make sure that you're not changing up your products or your active ingredients between the two split treatments either. You want consistency above everything and making sure that you're following those label rates and not going over the maximum that they can be used at for the year.

Whether you're applying to a warm or cool season grass, if you decide to put down a fertilizer and a pre-emergent on your lawn going into the fall and winter, both of these type of chemicals are ones that need a higher water volume to create that barrier that you want for the pre-emergent and getting all of those nutrients penetrating into the root zone so the turf can take it up and you see the results that you're looking for. You don't want to short yourself on water and short yourself on results.

After you apply your fall pre-emergent and fertilizers and any other nutrients your lawn may need, follow best practices for a winter and dormant lawn check for any limbs and debris that may fall over the time try to walk on it as little as possible and make sure that you keep it at a nice height right before your last mow so that it's healthy going through the winter. If you liked this video, make sure you give it a thumbs up, head over and hit that subscribe button, and check out our other DIY and how-to videos. Thanks for watching!