Fertilizer

When should I apply starter fertilizer?

We used to recommend holding off on applying starter fertilizer until 5–7 days after germination (or when you can safely walk on the lawn). The idea was to avoid fuelling a surge of top growth in your existing lawn while your new seed was still sitting on the surface—an approach you’ll hear from seasoned lawn enthusiasts more than in generic guides. That advice is still solid if you’re using a standard big-box starter fertilizer that relies heavily on fast-release nitrogen (e.g., urea or ammoniacal N). Those formulas can fuel established turf quickly, which isn’t ideal when seedlings are just getting started and competing for light, moisture, and nutrients. However, SeedLaunch Pro™ (our starter fertilizer) was engineered specifically for seeding projects to address this issue and is designed to be applied at the time of seeding. Meaning you apply it right before or right after you throw down your grass seed. This applies to overseeding or starting a new lawn from bare soil. If you’re not using SeedLaunch Pro™ or a professional fertilizer from the golf course industry, the “wait-until-germination” method remains a great way to keep things balanced with typical retail fertilizers. In all cases, follow the label rate and keep the seedbed consistently moist—your preparation and watering do most of the work; fertilizer helps you get the most out of it.

Which starter fertilizer should I use?

We recommend ours: SeedLaunch Pro™ Germination Maximizer + Starter Fertilizer 8-15-10. It's a professional turf formula engineered to enhance germination, support early root development, and deliver controlled feeding to drive new lawn establishment and give every seed the best chance to succeed. Big-box store starter fertilizers are all pretty similar and you can't really go “wrong” choosing one over another—provided you stick to the recommended application rates. If you're using a big box store starter fertilizer because you have some on-hand, consider waiting until after your new seed has germinated as these products usually contain high amounts of fast-release nitrogen, which can cause a surge of top-growth in your existing lawn while you wait for your seed to germinate.

SeedLaunch Pro™ Starter Fertilizer is Sold-Out. What Should I Use Instead?

If SeedLaunch Pro™ is sold out and you can't find a starter fertilizer from the professional turf industry, you'll likely have to use a big box store starter fertilizer. Big-box store starter fertilizers are all pretty similar and you can't really go “wrong” choosing one over another—provided you stick to the recommended application rates. In terms of when to apply, we recommend waiting until after your new seed has germinated as these products usually contain high amounts of fast-release nitrogen, which can cause a surge of top-growth in your existing lawn while you wait for your seed to germinate. The reason this isn't ideal is because the seedlings need to compete with the existing grass for light and nutrients. Waiting until after germination to put down fertilizers with fast-release nitrogen (most big-box) ensures you're not fuelling the existing lawn before your seedlings have emerged.

Should I apply a winterizer fertilizer?

A winterizer fertilizer is often talked about as a must-do fall step — but the truth is, it’s optional. It’s meant to help the plant store nutrients so it can bounce back faster in spring. And it can help in the right conditions, but it’s not essential for a healthy lawn. When it can help You can apply a winterizer after your final mow if: - The grass has stopped growing but is still green, and - The ground isn’t frozen yet. This short window usually happens in mid- to late October, depending on your region. The goal is to give the grass nutrients it can store for a faster spring green-up. When to skip it Skip the winterizer if: - The ground is frozen or your lawn is fully dormant - You’ve already applied a fall fertilizer in the past month - You’re seeing regular frost and the soil is cold most days At that point, the grass won’t take up much — it’s better to wait and feed in early spring. What to use If you decide to apply one: - Choose a fertilizer with slow-release nitrogen - Use a balanced or slightly higher nitrogen ratio (no need for high potassium) - Apply at a light rate and water it in if rain isn’t expected soon Bottom line A winterizer is a nice-to-have, not a must-do. If the conditions are right, it can give your lawn a small head start next spring. If not, skip it and focus on: ✅ Keeping your final mow around 2 inches ✅ Clearing leaves and debris ✅ Cleaning and storing your mower