#1 reason for poor germination: water! either too much or too little. Soil should never completely dry out (seeds will quickly die if soil is left dry for extended period of time), and should never be soggy (seeds will rot if left in soggy soils). Evenly moist soil is a must until seeds have germinated, and established themselves somewhat.

#2 Temperature - not too hot, not too cold! Typically a range of 60-72 degrees is the sweet spot.

#3 Light - seeds need light, and it needs to be fairly bright. A bright windowsill or greenhouse is great (for starting seeds indoors) but low light situations can be supplemented with a simple ‘grow light’ set up.

#4 Time - many seed varieties take time to germinate, sometimes up to a month. So be patient, and make sure to keep an eye on watering correctly while waiting.

#5 Storage - how long have the seeds been stored, and where were they stored? Seeds typically have a shelf life of about 2 years - after that, the germination rate begins to drop. And they need to be stored in a cool, dry location, out of direct sunlight.

Also, sometimes random things can happen to a planting site - such as birds eating a large amount of the newly planted seeds, or heavy torrential rains washing everything away.

You carefully loosen and rake the soil, broadcast the new seed mix, and water regularly just as the directions say. But a few weeks later, it seems that as many weeds have popped up in your newly seeded patch as blades of grass.

What went wrong?

Many assume the explanation is that weed seeds were in the bag of wildflower seeds, but post-seeding weed outbreaks are primarily the result of weed seeds that were already present in the soil.

Why the outbreak?

Weed seeds can be found in almost all soils. Ones closest to the surface sprout to become each season’s new weeds, while others work their way deeper, where they can lie dormant for decades.

When actions such as digging, tilling, and dethatching work these dormant weed seeds closer to the surface, the improved light and warmth there encourage them to sprout. The regular watering you do to encourage wildflower seed to germinate is the final ingredient that sprouts weed seeds with a vengeance, too.

What to do?

If you notice just a few weeds here & there, pulling these by hand is the best option. If the area is very large, and hand weeding is not feasible, spot treating the weeds with an herbicide such as glyphosate is an option. This will create bare spots, which can then be reseeded once the weeds have died & been raked out. Do not use broadleaf weed killer on the entire planting site, as this will kill the wildflowers and many components of the flowering lawn mix.

Prevention

To prevent dormant weed seeds from ruining your new site, there are a few things you can do to help.

1. Don’t till or rake site deeper than necessary (2”). This will prevent many of the dormant seeds from working their way to the surface.

2. You can also water the planting site after tilling/raking, wait for any weed seeds to sprout (about 7-10 days), then spray with glyphosate. Wait for the weeds to die, and then proceed with planting your new wildflower/flowering lawn seeds.

3. If you do not want to use herbicides, black plastic can also be used to smother the newly sprouting weed seeds after tilling/raking. The downside to this method is the time requirement - typically the plastic needs to remain in place at least 2 months to be effective.

It varies, but the ballpark answer is 2 years. After that, the germination rate begins to drop. You can extend the life of your seeds by ensuring they are stored in a cool, dry location, out of direct sunlight, in a sealed container. An unheated garage is great!

It depends on the weather/temperature. The majority of seeds prefer consistent temps between 60 - 72 degrees F. For many people, this falls somewhere between late March thru May, and Sept thru mid Oct.

You can also click HERE to find your planting zone, which is helpful for figuring out optimal planting times for your location.