So far in our Restoration Best Practices blog post series, we’ve covered Developing an Ecological Restoration Plan and Site Preparation, which is particularly important if you’re planning to use native seeds to restore your site. Whether it’s a prairie, wetland, forest or another type of ecosystem, the survival and success of your native seeds is entirely dependent on having low competition from non-native plants and nice, loose soil in which to put down roots. We encourage you to go back and read those two posts if you haven’t yet. (Remember, a Restoration Plan is required if you are buying seeds from RNPP this fall!)
In this blog post, we’ll discuss some of the reasons for using native seeds vs starts and how to choose seeds for your site. Then we’ll move into some of the technical details of creating a seed mix and introduce our calculator tool for figuring out how much seed to buy.
Growing plants from seed is more work than buying plants already established in containers. So why do it? Here are a few reasons:
- Diversity. Here in the Rogue Valley, growing from seed gives you a much wider array of species to choose from. Not all plants are going to be available in containers.
- Success. Some plants don’t survive transplanting very well, and plants actually have the remarkable ability to adapt to a site as they grow. So, the moment a plant puts down roots in your soil, it is learning about the local conditions and setting itself up for faster, stronger, healthier growth.
- $avings. It’s much cheaper to grow a thousand plants yourself from seed, than buy all those plants in containers!
- Fun. You’ll learn much more about the native plant life cycle by watching them grow from seed. There’s nothing like seeding a site in fall, then coming back in the spring and seeing the brown earth covered in green!
Selecting Your Seeds
In restoration work, it can often be difficult to decide what kind of plant community to establish, especially in sites long dominated by non-native species. It’s important not only to look toward the past, understanding what plants might have grown in your site (perhaps prior to the disturbance that caused non-natives to move in), but also toward the future. How might conditions change, and what plants are best suited to adapt to those changes – be it drought, flood or fire?
Seeds should be selected based on your restoration goals. Are you creating a pollinator meadow or trying to stabilize a streambank? Hopefully, you’ve already laid out these goals in your Restoration Plan. Your seed mix, plus any remaining weed or native seeds that survived the site preparation process, will be what determines the type of plant community that comes up in the spring (or fall if your seeding happens in the spring – see our Site Prep article for a discussion on the best time to plant your seeds).
Before you purchase seed, be sure to do some research on the plant and the conditions in which it likes to grow. This way, you can avoid planting seeds that will not be successful in your site.
There are two common ways of actually getting the seed on the ground: broadcasting by hand and drill seeding using a tractor.
- Broadcasting. Best for smaller sites (half an acre or less). To broadcast seed, simply walk in a regular pattern across your site, throwing by hand and attempting to distribute it as evenly as possible. Or, use a “belly-crank” seeder. In either case, broadcasted seed should be distributed at a higher seeding rate than if using a drill seeder. Because broadcasting doesn’t actually bury the seed in the soil, these seeds have a slightly lower rate of success, and may be eaten by birds and field mice! On smaller scales, this effect can be mitigated by raking, or rolling over the seed to press it in.
- Drill seeding. A drill seeder pulled behind a tractor is a fantastic way to distribute seeds evenly and get them in the soil without turning it over (bringing buried weed seeds to the surface where they can germinate). A seed drill doesn’t do any actual drilling; it can be more accurately described as placing the seeds underground, at a rate and a depth specified by the user.
Belly crank seeders and rollers can usually be rented out by the day from a local farm supply store, home improvement store or equipment rental business. Jackson Soil and Water Conservation District has a drill seeder for rent.
Seeding Rate Calculations
By choosing a specific seeding rate and sticking with it, we can introduce scientific accuracy to the art of restoration. We start with a target seeding rate and work from there.
What is seeding rate? Simply put, it’s the number of seeds you need to apply to a given area to achieve the desired plant coverage. Most restoration projects use a seeding rate of between 30-60 seeds/square foot. Knowing your seeding rate will help you determine the number of pounds or ounces of seeds to purchase.
What’s the ideal seeding rate for your site? It depends on your goals, seeding method and site conditions:
- At the lower end of the range (30 seeds/sq. ft.), you’ll be seeding a site that has been well prepared (no weed seeds; flat, smooth soil surface), and has excellent soil. You have a seed drill or some other way of accurately distributing the seed, and you want plant coverage to be somewhat sparse (perhaps for bee nesting habitat).
- At the higher end of the range (60 seeds/sq. ft.), you are trying to seed heavily to outcompete weeds that survived your site prep, there’s a slope or other factors that could cause seeds to wash or blow away, and your goal is to have dense plant coverage at the site.
Now let’s talk about your seed mix. You don’t want a monoculture of one seed in your restoration site, but a mix of different species — it goes back to that plant community idea we were discussing earlier. Before you can figure out how much of each seed to buy, you’ll need to decide on what percentage of the total mix that each type of seed will occupy. For example, if your goal is to restore a native grassland meadow, you might shoot for 50% Danthonia californica (California oatgrass).
Finally, the seeding rate is dependent on the number of seeds per pound, which is different for each species. If you plan to purchase seeds from the RNPP Seed Sale, you can find the number of seeds per pound on the species description page or here in this handy table.
How to Use the Calculator
We created this spreadsheet as a quick method of calculating the quantity of seed you need to buy. You’ll need to first input the following data:
- Your target seeding rate (# of seeds/square foot)
- The number of acres to be seeded
- The names and number of seeds per pound of each species you want to include in your seed mix (seeds/lb can be found HERE or on the species description page in the RNPP seed sale).
- The percentage of the seed mix that species will occupy
- The cost per pound for each species
Here is what the calculator will give you after you enter the data above:
- How many pounds of seed you’ll need for each of the species in your mix
- The individual seeding rate for each species in your mix.
- The cost per species
- The total cost of your seed mix
Ready to get started? Download the spreadsheet by clicking here and give it a go!
Tuula Rebhahn has spent the summer as Ecological Science Intern with The Understory Initiative. When she’s not out in the field counting plants, she’s a freelance writer and editor. Connect with her on Facebook or LinkedIn!