Seeding Cool Season Lawns In Spring

Cool Season Lawns - Kentucky Bluegrass, Perennial Ryegrass and Turf Type Tall Fescue - should you seed these in the spring? Why or Why not?

Let’s get into this!

So you’re looking at your lawn here in the early spring and you’re wondering if throwing down grass seed is a good idea.

At face value, it seems to make sense to seed the lawn in spring. You have temperatures rising from winter into spring but staying rather mild - and lots of nourishing rain and intermittent overcast skies to keep things from drying out.

Conditions are ideal.

Crabgrass is a Spring Annual Competitor

The thing about ideal conditions is they are also ideal for the natural enemy of your new growing turfgrass seed - and that is crabgrass. If you seed new grass in spring, just as your grass babies are growing and stretching for sunlight and sending down roots, crabgrass babies will also be competing directly alongside them.


Crabgrass Life Cycle

Crabgrass is a summer annual grassy weed. The term “summer annual” means the plant grows from seed in spring, strengthens and spreads in summer, and then dies just before winter while dropping seeds. Thousands more seeds. These seeds start the process all over again the following spring.

Crabgrass is one of the worst problems you can face as a DIYer and it strikes lawns in almost every state in the US and Canada.

In the picture here you can see crabgrass that has broken through a Kentucky Bluegrass lawn, not only along the edges, but now well into the turf. Those areas get larger and larger year after year as more seeds are deposited and eventually there will be no more Kentucky Bluegrass on this strip.

Crabgrass lives fast and it dies hard. Because it’s an annual, it knows it’s only got one summer to grow big enough to support a big seed production for the following year. It’s adapted to spread wide and push out competitors for this reason.

Now picture your fledgling Kentucky Bluegrass that has just started to grow and summer heat hits it for the first time. It’s not really had alot of time to get very strong by summer and summer is really hard on Kentucky Bluegrass anyway.

You know what though? Crabgrass loves the dry hot summer. Many times in the worst, most dry summers, you’ll see a lawn of Kentucky Bluegrass completely dormant and there will be patches of green crabgrass throughout.

What I am saying here is that crabgrass is bred to out-compete new Kentucky Bluegrass and turf type tall fescue and rye grass too. It’s fierce.

crabgrass curb

Here are some closer videos of crabgrass if you need help with identification. Just keep in mind, you won’t actually see crabgrass this big until later in the summer or early fall.

So like I mentioned, crabgrass is one of the worst problems you can face because it loves the ideal conditions of spring, especially all the rain; It’s the spring rains that wake up the seeds that were deposited last winter.

It’s a fast starter that will out-run everything around it, especially through the driest of summers. If left unchecked, it will choke out more and more of your good grass until you don’t have any left.

You know what else?

Stopping Crabgrass Is Easy

It’s extremely easy to reverse the cycle and stop it in your lawn. You can prevent it from ever growing using herbicides known as “pre-emergents.” I recommend one called Prodiamine and you apply it in early and mid spring to stop the crabgrass seeds from germinating. Once applied to the lawn, they cannot grow for a period of 5-6 months. It locks them out.

However, that same chemical, prodiamine, will have the same effect on your grass seed that you plan to throw down on the lawn this spring. It will stop the crabgrass, as well as your expensive grass seed you plan to throw down.

Seed Your Lawn In Fall

So now you have to make a choice. Do you want to risk the crabgrass out-running your new grass seed? My recommendation is no. I recommend you opt to apply crabgrass pre-emergent in spring and seed your lawn in the fall.

While throwing down crabgrass pre-emergent prodiamine, I also recommend that you fertilize your lawn every 4-5 weeks in spring and into summer so that your existing grass can thicken up all on it’s own. Feed it like a beast.

And then on top of that, mow often. The more you mow, the healthier your lawn will grow. No one says you can only mow once every 7 days on the weekend. Throw in that Wednesday night mow and really push that grass so it drives deeper roots and thickens up. Mowing frequently does that.

Follow these three simple strategies:

  • Prevent Crabgrass
  • Throw Fert Monthly
  • Mow Often

Then of course when you get to summer keep it irrigated and by the time you get to the fall, you may not even need to seed! Your lawn may surprise you and look really good when you take care of it like I am recommending here. If you have never really cared for your lawn before, I always recommend giving it the spring and summer all on it’s own to show you what it can do. You support it with lots of mowing, and lots of throwing (fertilizer) and let it enjoy those ideal spring conditions. Many of you will find that there is a healthy lawn living there just ready to be let out!!

If you want a custom schedule that tells you when to apply all these products and also tells you the ideal time to seed in the fall, download my free DIY Lawn Care App here.

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