How To Plant Grass Seed in Springtime
This post was originally published on Reddit. Some of the contents have since been edited 2020-03-12.
There’s a lot of confusion and debate around spring seeding for cool season lawns. Some say it’s impossible and beg not to wait until the late summer and early fall – while others spread seed as soon as we “spring ahead” into March and April.
This is my personal guide – based in Massachusetts, Zone 6b – to spring seeding. Results may vary and are mostly contingent on the location and …
You need patience. While we’re nearly in the midst of a heat wave for March here in Massachusetts, you need to be sure that the last frost is behind you. This means, even though there’s been some perfect air and soil temps, there’s still risk of killing newly germinated grass. So ensure temps are consistently in the 50s with no ice or snow on the grounds (think first two weeks of April here in Mass.).
Clean up all the material on existing. This includes, but not limited to leaves, sticks, mulch, dead grass and rocks.
Core aerate (double pass), add compost (if needed), level, and scarify to get good seed to soil contact. If there is some turf on the lawn, scalp with a mower as low as possible with a sharp blade and dethatch/scarify.
Enhance the soil with Kelp4Less ExtremeBlend or Green Lawn & Turf. These contain essential humic, amino, and fulvic acids for your soil, along with sea kelp. The latter also contain molasses powder and iron sulfate (use coupon code NELCA for 25% off). These products can be both applied before or during seeding (below).
Find a good quality seed like Jonathan Green Black Beauty Ultra or GCI TTTF and aim for 5-9 lbs. per 1,000 sq. ft. depending on how severe the seeding is going to be. Think a heavy overseed (5-7 lbs. Per 1,000) vs. brand new lawn (upwards of 9 lbs. per 1,000 on bare dirt).
Using a rotary or drop spreader, or slice seeder, make sure the seeds are evenly distributed throughout the area. More does not mean better! In fact, if you over-overseed, the competition for soil space and nutrients will be so great that you will have a bunch of die-off.
Please note that these two grass seed brands mentioned are not exhaustive. Choose the grass seed species and blend that is best suited for your exact zone. Websites such as Seed Super Store and Natures Seed are two other options that can also help answer these questions.
Springtime is often ideal temps and times for fungus to start brewing. Increases in daytime and nighttime temps, humidity levels, and rain (akin to 2019) are perfect stomping grounds for diseases. As the seed germinates (between 7, 10, 21 days for Ryegrass, Fescue, and KBG respectively) the new grass is approaching favorable conditions for fungus. Make sure you add a preventative such as Propiconazole and/or Azoxystrobin.
Liquid or granular fungicides will not interfere with your seeding.
Fertilizer & Pre Emergent
Very important and often confusing to most. We can go a couple of different routes here:
- Simply use an organic (slow release nitrogen) and synthetic starter fertilizer (fast release nitrogen) with crabgrass control. I prefer Jonathan Green 10-15-10 starter with crabgrass control. This contains Siduron (tuperspan) which has an efficacy of ~6 weeks in the soil as a pre-emergent.
- Same as above but you may substitute Scott’s Starter with Mesotrione (Tenacity) for Jonathan Green. However, the pre-emergent qualities won’t last quite as long as Siduron.
- Use a combination of a organic (slow release nitrogen) and synthetic starter fertilizer (fast release nitrogen) at full bag rates. Milorganite is popular, but some Milorganite Alternatives that I’m partial to Jonathan Green 8-0-1 (for 0.6 lbs of N per 1,000) and Lesco Starter 18-24-12 (for 0.72 lbs. Of N per 1,000). Mix ½ tsp of Tenacity to 1 gallon of water to cover 1,000 sq ft. Water it all in and do not use a non ionic surfactant (NIS).
You may want to lightly cover your seeds with peat moss or Pennington’s Slopemaster. This will help prevent runoff, limit the amount that birds will eat it up, and help keep it damp. Make sure seeds stay moist! This is most important! A quick 10 minute shower anywhere between 2-3 times per day should do the trick.
Keep off the grass! The new grass cannot be trampled on. Like Step 1 under weather, you need patience. This is a grueling process that can be a bit pricey. So don’t ruin it by sudden foot traffic.
Mow and bag your new grass with a very sharp blade and very clean lawn mower once the grass has reached at least 3” in height. Sharp blades to prevent bruising and tearing, which then can lead to an increase in diseases. And a clean lawn mower, to help prevent cross contamination (if any fungus or diseases was present).
Roughly 6 weeks post germination, and after the lawn has been mowed 2-3 times, add Lesco 19-0-7 Dimension. This has post emergent qualities than can kill crabgrass and dandelion up to the 3rd leaf stage. It also acts as a fine pre-emergent that can help you control crabgrass and ward off any additional weeds throughout the summer.
You can continue to spoon feed Nitrogen at 0.25 lbs. per 1,000 every other week. Use a Nitrogen Calculator to help with application rates. I also highly recommend the soil amendments – specifically Kelp4Less – bi-weekly throughout the growing season. This is a fantastic product and is safe to use all season long.
I hope this helps demystify and take the stress out of spring seeding. Would love to hear feedback in the comments!