Using Native Plant Material
Ever see one of those bumper stickers that says, "Always late, but worth the wait?" If native plant seeds could drive cars, those stickers would be on them. Oh, they may require a bit of patience, with germination taking any-where from 30 to 90 days, but once their green shoots finally do arrive, you'll be glad you stuck around to greet them.
If you've been hydroseeding for any length of time, you already know this. That's because there's a growing movement toward using native plant material as much as possible, especially on government or commercial projects.
Using the flora that is indigenous to an area is one of the core philosophies of the growing eco-green, sustainable landscape movement. When you want to use fewer chemical fertilizers and insecticides, and increase the amount of forage for our pollinators, you turn to native plants.
Another big driver of native-plant landscaping is drought. Because natives are adapted to their local climates, soil conditions and average precipitation rates, they're much less thirsty. That makes them ideal for use in areas where irrigation isn't available, such as along the sides of many highways, or anywhere you need to conserve water.
The desire to gather LEED points is a spur for many commercial developers to specify natives. And many times, they're mandated. Federal, state and local governments are increasingly passing laws requiring that new plantings on landscapes under their purview consist solely of drought-tolerant native species.
Chuck Caverly is account manager and botanist at Native Landscape Solutions, Inc., in St. Louis, Missouri. One of his specialties is prairie restoration.
When he designs one, he’s looking for a variety of forbs so that there will always be something flowering, whether it’s April, August, or October. The goal is to have it look pretty and be attractive to both people and pollinators.
Different ground conditions dictate what species he’ll use. “There are plants that we’ll put in where there’s a lot of shade, others we’ll use in swampy, wet areas, and still others that are better for a classic prairie, full of dry, grassy knolls.”
He said that natives tend to have deep root systems, making them a great choice for stabilizing hillsides and slopes. Where the roots of fescue grasses may go down anywhere from eight to 16 inches into the soil, natives will send tendrils down three to five feet or more. These plants also do well in rocky areas because of their ability to seek out hidden moisture.
They even have a role in the company’s other ecological work. “We plant them in stormwater basins, because they help clean the water, sequestering heavy metals and using them as micronutrients,” said Caverly. “They’re locked up by the plant and stay out of the stream, so they help prevent algal blooms.”
Doug Bauer is president of DJM Ecological Services, Inc., and Pure Air Natives, Inc., a native seed company, both in St. Louis, Missouri. DJM does a lot of site reclamation work, for which native plants are preferable most, but not all, of the time.
“They’re situationally appropriate, as they’re generally better adapted for a particular environment, because that’s where they’re from. But they’re not a ‘silver bullet.’ You can’t just throw a bunch of native seed on the ground and have it solve all your problems.”
However, there are some problems that they will solve.
“It’d be very foolish to plant anything that doesn’t like our climate, our soil, or our winters and summers,” said Dave White, owner and president of A&D Hydroseeding, Inc., Kuna, Idaho. “We use custom-blended seed mixes of grass varieties that are accommodating to those issues, and that look nice.”
In some instances, his choice is dictated for him. Many of the CC&Rs on newer housing developments in his area require that front yards be sodded for instant “curb appeal.” Only back and side yards are allowed to be hydroseeded. So that everything matches after it’s all grown in, he makes sure to use the same species of native grasses as the local sod growers.
As we mentioned, slow-but-steady natives take a little more patience. Caverly says, “If I hydroseed a slope with fescue and get a couple of good rains, after 90 days, I’m mowing it. But if I hydroseed that same slope with natives, it’ll take about 270 days before I can mow.”
Because of their pokey nature, these seeds need some help staying put, especially when sprayed on hillsides. A big storm could wash them away. “Because they germinate so slowly, we’ll use a heavier, woodfiber mulch,” said White. “On slopes, we’ll also use a bit more tackifier.”
That’s fine—but what if you’re working under a permit that says you must have new vegetation growing on your site within 30 days, but it’s going to take twice to three times that long to see the evidence?
Well, that’s where cover crops come in. Mixing in some non-native grasses that can be counted on to come up within five days are your insurance policy here. The cover crop will hold the soil in place and form an umbrella over the native seeds, allowing them to take their sweet time emerging. Caverly will use spring oats, winter wheat, or annual rye, because they’ll be good for a full year.
“Sometimes the pure natives do struggle a bit,” said Scott Wadsworth, owner of Enviro-Systems of Utah, LLC, in Payson, Utah. “A lot of native seeds have harder casings, so they take a bit more time to crack open and germinate.”
To give them that time, he’ll pair the natives with faster-sprouting, non-native crested wheatgrass. This combination works so well, it’s often specified in National Pollutant Discharge Elimination System permits.
When you seed depends partly on local conditions. Erik Burr, owner of TerrawoRx Services, LLC, in Albuquerque, New Mexico, says. “When they write specs here, they take our monsoon season into account.”
“That typically starts in mid-June and runs through mid-August. That’s also the time of year when the soil temperature reaches 60 degrees, which natives in our climate have to have in order to germinate. So that’s our window.”
Soil and water
One of the great benefits of native plants is that they generally need very little in the way of soil amendments or fertilizers to make them grow. Wadsworth says that he rarely encounters situations where he needs to fertilize or add organic matter.
An exception to this is a site where the topsoil has been stripped off or has been badly depleted. Before Bauer does any hydroseeding on such sites, he gets a detailed soil analysis to see what nutrient deficiencies may exist.
It’s a good thing that native grasses aren’t as hungry for fertilizer as standard turf grasses, since they’re often used in environmentally-sensitive areas. “If you’re seeding near a creek or something, they don’t want you to use chemicals that could possibly get into that body of water,” said Bauer.
You may not need to add anything to the soil, but roughing or loosening it before planting definitely helps, says Wadsworth. “A lot of times, we’ll go ahead and spray the seeds on first, then rake them into the soil. Then, we’ll apply the mulch on top of it.” He finds this method to be more effective than mixing the seed and mulch together.
The reduced need for irrigation is a big selling point for natives, adds Wadsworth. After the initial establishment watering, they can go all through the entire summer without any problems.
Burr hates to see people filling their front yards with rocks in an attempt to use less water. “We’re encouraging homeowners who want to switch out their lawns to go with a native-grass-and-wildflower-meadow option. Once you get the grass and wildflowers up, you only need to water once every two weeks, or once a month.”
He tells them that the grasses he’ll plant will be genetically predisposed to hold onto moisture. And, because they’re getting some minimal irrigation, they’ll grow stronger and be greener than the yellowish native grasses they see in the natural desert environment, out on the surrounding mesas.
How much seed do you need?
The rate and density at which natives grow, and a bureaucratic non-understanding of that, led one Georgia hydroseeding contractor to give up doing highway jobs. “A stand of natives can take a couple of years to get established to where it’s thick and fat, and that’s mainly because a lot of folks don’t use the right amount of seed,” he says.
He thinks there are two reasons for this. First, native seed is expensive, so soil and water conservation agencies and state highway departments want to use as little of it as possible. Second, they don’t seem to understand the difference between drill-seeding and broadcast hydroseeding—at least not the ones he’s dealt with—and will specify seeding rates based on the former.
“They’ll want you to use ten pounds per acre, then complain that it’s our fault when it doesn’t grow,” he said.
For years, he worked hard to try and appease government specifiers. That is, until one particular job.
“On the last highway contract I did—fifteen years ago—I was told, ‘This is probably the best-looking stand of grass in the state. But we can’t pay you, because you used 40 pounds of seed per acre, and the specs say ten.’” Then he was told that if he pressed for his check, he would never do any more work with road companies. “Fine,” he said. Since then, he’s stuck to working for private developers, creating subdivisions. “They love us, don’t ask stupid questions, and we get paid.”
Since natives are being specified increasingly, especially in roadside applications, the type of difficulty he experienced should happen much less frequently.
Because Caverly feels that maintenance is so important, he won’t sell any native seeding job without a three-year stewardship contract that includes mowing and weeding. Mowing is essential to establishing a prairie or meadow, he says. You mow the planting once in the fall or winter, after everything’s gone dormant.
In the spring, it’ll come back as a nice, full, thick, meadow look.
“A typical native-seeding regime is a three-year period,” he said. “You seed, then nurse the planting right through the third year. It’s not really until the end of that third year that it can stand on its own.”
By “nurse it,” he means going after annual weeds. To keep them from messing up his mix, Caverly’s crews spend a lot of time cutting and collecting weed-seed heads.
They watch for invasives like lespedeza, thistle or curlydock. “Things that are really heavy seed producers can take over. They’re aggressive annuals that’ll get overgrown, push out the natives, and create a monoculture.”
Weed seeds aren’t the only ones gathered. After the wildflowers and forbs finish blooming and set seed, his crews go in and collect it. They’ll look for areas in the site that are light in certain species, and redistribute it in those spots.
How native is “native?”
The need to use quality seed was stressed by every contractor we talked to for this story. “You have to use very high quality seed, especially on residential lawns,” said White. “Anybody who wants to stay in business will do that.” But how can you be sure you’re getting it?
Bauer says the only way to really know is when it’s been tested by a third party, such as the Indiana Crop Improvement Association or similar entities.
He says that a lot of native seed is sold in bulk, which means it hasn’t been tested; you have no way of knowing how much of it will actually germinate. According to him, there’s no standardization of, or regulations governing, the sale of live native seed.
An independent lab will put the seed through purity and germination tests. For instance, a lab should be able to tell you, with absolute certainty, that a certain lot is 95 percent live seed, and that 50 percent of the viable propagules are ‘hard seeds,’ meaning they won’t germinate until the second year.
The term “native” is itself open to interpretation. “How native is ‘native?’” asked Caverly. “That’s the great debate within the native-seed industry. Native to the region? The state? The county?” How far does the distinction need to be narrowed down? He said that to some horticulturalists and native plant advocates, it isn’t enough that the seeds being planted will grow the same plants found near the seeding site. These purists contend that seed needs to be harvested from no more than 50 miles away, or you can’t really say it’s “native.”
But “not every state has native seed sources,” said Caverly. “Say a certain species grows like wildfire in Wisconsin, but here in Missouri, it’s rare. If I go to a local seed house for that, it may cost me $125 a pound. But if I buy the very same species from a seed nursery in Wisconsin, it’s $30 a pound.”
Going native takes some patience, but it is rewarding—aesthetically as well as monetarily. When you look out at that beautiful wildflower meadow or sustainable stand of green grass that you planted, we think you’ll agree that it was definitely worth the wait.