Because their root systems infiltrate the soil and bind it together, plants are an integral weapon in the war against erosion. However, as installing mature plant material is usually cost-prohibitive, most contractors plant seed on their sites. At least, that’s the intention. A stiff wind, a downpour, or hungry birds all can make a huge dent in seeding efforts, especially if the seed is surface-applied. In addition, different species of plants prefer different seed-planting depths; planting at various depths would produce optimum results, but the costs would be astronomical, especially on sites planted with a variety of species.The commercial solution? Don’t lower the seed, raise the ground. No matter how it’s applied (e.g., hydroseeding, terraseeding, broadcast spreader, conveyor), seed is combined or followed with an application of compost, mulch, and/or soil that gives the seed cover. Once sown, it’s then up to the seed to germinate.Seed Germination FactorsSoil depth is important because seeds have only a certain amount of “energy” stored in the endosperm; if buried too deeply, emerging seedlings don’t have enough strength to push their way out of the soil and into the sunlight.Temperature, of both the soil and ambient air, also factors in. Seeds need to bask in the right soil temperature for a certain amount of time before they will sprout. If the temperature is lower than optimum, sprouting is delayed. Higher soil temperatures accelerate the process, although abnormally high temperatures can kill the seedling.Many plant seeds shouldn’t be planted before last frost; however, even when temperatures stay above freezing, the ambient air temperature can cool the soil, even on sunny days when dark soil attracts sunlight/heat (sometimes becoming warmer than air temperature). On the obverse side, some seed species need to pass through a cold season (dormancy) before they will germinate. In a natural setting, after dropping seed, some species will begin seedlings immediately. Other species’ seeds lie on the ground, getting underground only during winter’s frost/thaw ground heaves, and push up new seedlings after the cold-season dormancy. To simulate this natural cycle, seed companies often give collected seeds a dormancy period to ensure that their product will germinate.
Echinacea (purple coneflower) sometimes needs birds’ help to distribute its seeds.Certain species’ seeds need more help. For example, Echinacea seeds are securely fastened to the seed head, but American goldfinches eagerly munch on the plant, pulling out the seeds. What seeds the finches drop often sprout the next year. Other species’ seeds, possessing a hard seed coat that inhibits germination, might need to be fully digested by a bird or other animal; the seed coat is scarified by stomach acids, and when the creature eliminates, the seed can then germinate-sometimes while conveniently resting in nutrient-rich manure! To simulate this natural cycle, seed companies might give these collected seeds an acid wash.Finally, seeds need water. Too little, and they won’t germinate; too much, and they will wash away with the rain or their seedlings will rot (also called “damping off”).Kernels of Wisdom Bulk-seed companies offering various turfs and grasses are headquartered across the nation, but-in response to increased demand for “natural” or native plantings-many wildflower seed companies have sprouted up among them in the past decades. Applewood Seed Company of Arvada, CO, has produced wildflower seeds since 1965. Initially the business existed on a small scale, selling seeds to wildflower gardeners in hand-painted packets. As interest in wildflowers grew, however, Applewood began selling in bulk to the commercial landscape and wholesale seed industries. Today the company offers more than 150 species of wildflowers and grasses, as well as 35 wildflower mixes designed for a variety of growing conditions. “We’re not only a provider of seed, we also provide information about how to do the seeding,” General Manager Norm Poppe explains. “We work with contractors to educate them about the peculiarities of wildflower seeds. Many companies are not totally comfortable with the [wildflower] species specified in their projects; we want to transfer knowledge about the seed to contractors.”In a perfect world, seeds would be planted at the optimum time; in the real world, weather conditions and construction schedules often cause planting delays. “Perhaps the perfect time to seed is March, but construction delays push planting off ’til May,” Poppe says. “We’ll tell contractors what to do to help the plants “˜catch up,’ what they can do to deal with the reality of the situation.”
The endosperm gives the seedling energy to grow and emerge from underground.Sometimes the calendar can’t be pushed back. “We got a phone call asking about planting sunflowers in the Lake Erie area around the fourth of July. That would not be a successful project, and we told them so,” Poppe adds. The majority of Applewood’s customers sow their seeds with the broadcast method, either by hand or with an all-terrain vehicle or a farm tractor. As lightly covering the seed with soil is recommended, customers either hand-rake or drag chains behind machinery. “Some customers use drill seeding or hydroseeding,” Poppe observes. “We advise them that their results will depend upon the methodology, the brand of equipment, and the operator’s skill.”When hydroseeding, contractors usually choose one of two ways to get the job done. “In one method, seed with minimal mulch and fertilizer is applied, which puts the seed in close contact with the soil, then the crews come back a second time to apply mulch. This extra layer is like putting seed in a greenhouse,” Poppe says. “In another method, one typically used with lawn or grasses, contractors put a higher rate of seed in the hydroseeding machine and apply the mixture once. The higher rate is to ensure more germination. It’s thought to compensate for seeds that don’t come in contact with the soil. It’s a cost-accounting issue. People do it this way because they say it’s cheaper than doing it twice.”For planting more than one species on a site, Applewood suggests putting all the species into the mix at the same time, rather than seeding a cover crop first. “Make sure you get seed-to-soil contact,” Poppe warns. “You can’t just throw it out there and hope it works itself in. The farther away you get from seeding the correct way, the less success you’ll have with the site.” He points out that landscapers wanting a uniform, predictable site shouldn’t plant wildflowers. “In a natural setting, there are no absolutes-it all depends on the soil, the rainfall, the temperatures, and how conducive the situation is on the site. Where there’s drainage, some species may thrive; 50 feet farther, something else may take hold. What will happen can be unpredictable, especially with wildflowers, but this will make the ecosystem better. You want uniform? That’s not going to happen. Different situations may help or hinder different species. The flowers may grow in a “˜mosaic’ pattern. Anyone predicting how the site will eventually look will suffer disappointment if they don’t understand this.”
Applewood’s Low-Growing Mixture with annual and perennial wildflowers enhances this power station.When’s the best time for streambank restoration? “Depends on what part of the country,” Poppe says. “Early spring or dormant [fall] planting is usually best, but you have to take into account natural processes. Moisture is the biggest limiting factor. In the highest percentage of cases, problems arise from lack of moisture. Before planting, you need to think: Will moisture be there at the right time? Your planting really depends on rainfall patterns, especially in riparian areas. Unless you’re planting in the mountains, July is too hot-unless watering is done on the site.” According to Poppe, planting techniques don’t vary from season to season. “The only difference is, in summer you have to take supplemental water to the site. Contractors must lower their expectations if they don’t sow seed at the right time. How far away from “˜optimum’ [planting time] are you? How can you mitigate that? If once a week you could bring more water, that’s something you should consider.”A Side Order of MulchCompanies selling seeds across different climates can help customers find the right mix of seeds. “We sell to a large area in the western US,” reports Bill Agnew, general manager of Granite Seed in Lehi, UT, “as well as into Mexico and Canada. We offer specified seed mixtures and will develop them in a geographic area, which is good for the native plant community.” Granite sells more than 600 species of seed, as well as the accompanying mulch, tackifier, water-absorbing copolymers, and polynetting fabrics to help stem erosion.
Along with wildflowers, shrub seed is a large part of Granite’s business. “We offer fourwing saltbush and winterfat; sagebrush is another popular variety. These shrubs are mainly for wildlife plantings, for deer browse. Of course, with a shrub you need two to three growing seasons before you see how well the plant is developing. We counsel clients on when and how to plant. In our main area, the semiarid southwestern US, late fall, the dormant period, or early spring, are the best times,” Agnew says.
Corn poppies, popular annuals with delicate crepe paper-like petals, explode in color on these hotel grounds.The company’s main customers are state departments of transportation; state and federal agencies, such as Fish and Wildlife and the Bureau of Indian Affairs; contractors; and the mining community. Granite also has a turf division that works with homeowners and sod growers. “More people these days have an interest in native plant materials and xeriscaping,” Agnew notes. Is there any advantage to mixing seeds or staggering planting to achieve ground cover when it’s needed? “It depends on what you want to achieve,” Agnew explains. “We provide separate materials, but usually mixes containing different grasses, forbs, and shrubs. It all depends what the end target is too. Planting a roadside? Maybe you’d want more flowers. For reclamation or erosion control? More grasses. Planting for wildlife? Maybe your mix should contain more shrubs.”Agnew recommends hydroseeding for some projects. “Good performance, with good immediate erosion control at a relatively low cost. It works very well on places where you don’t plan to go back and water again, and it’s good for mulch cover so your seeds don’t blow away.” Granite sells mulches made from virgin wood fiber. Canfor’s EcoFibre and Conwed’s Conwed Fiber, virgin (processed) mulch products, feature long wood fibers that intertwine to form a rigid bond and are often used with tackifier to provide soil protection. Hydroseeding Makes Many Projects Possible
Hydroseeding equipment can be used for a variety of purposes. Here a T330 HydroSeeder is used to give a landfill an alternative daily cover.
Landfills often reclaim and seed a portion of the site while keeping others open. Hydroseeding has helped revolutionize the site reclamation process. Seeding, which once required weeks of manual labor, is now finished in a matter of hours. Mark Mather, general manager of Cincinnati’s Petro Environmental Technologies, recounts how the process helped his firm turn a mountain of trash into a golf course in Columbus, OH, aptly named Phoenix Golf Links. “This was nearly a million-yard earth project,” Mather says. “First we covered and capped the 185-acre landfill, adding a minimum of 24 inches of soil in phases, over 20 days. The site isn’t flat; we had some slopes in excess of 1:1 [45% grade]. We used zero straw-the project was 100% hydroseeded, no sod. We hydroseeded the greens, the bunker surrounds, and-although we drilled a little bit-the fairways and tees. We began grading in fall ’99; by spring 2000, there were golfers out there.”Mather has used the same machine, a Finn 350 HydroSeeder, on other projects too. “Last year we sealed a uranium onsite disposal facility. We used the HydroSeeder to lay down an emulsion product for dust control and to apply tackifier. The HydroSeeder worked well, even on a 6:1 slope. We also used a Finn machine as a power washer to spray water to keep down dust and for washing roadways, which saved us from needing another truck.”In Staffordsville, KY, the firm Green Mountain provides land reclamation services to the mining industry and to commercial and residential clients. Owner Tim Wheeler admires hydroseeding’s efficiency. “If you have a volume of work, hydroseeding makes it much faster,” he says. “Also, it can lower cost to my customers because it’s more efficient, with no raking. I can apply seed, mulch, fertilizer, and lime-all in one application!”Green Mountain, which serves customers in eastern Kentucky and western West Virginia, owns three Finn T330 HydroSeeders. “For reclamation projects, a three-person crew can hydroseed 5 acres in one day,” Wheeler claims. “We can do 20 acres a day on average, with two HydroSeeders and a six-man crew. On the landscaping end, production is not as good, but we can still easily do 10 to 12 acres a day. Of course, we have one of the best crews in this area: Once, we did 40 acres in one day!”Such efficiency helps keep Green Mountain on schedule. “If the weather conditions are good, in season, we must get these jobs done,” Wheeler explains. “The best times to seed are from February 1 until the end of May. Then, because there isn’t much rain, we don’t seed much in the summer-maybe in shady areas, or north sides of hills, where you don’t have to worry about water. We’ll start up again around September 1, and sometimes we don’t stop. Depending on the weather, we may work right through winter.”No Sense to Toil If You Don’t Have Good Soil
Revegetating extreme slopesOf course, the best seed and seeding practices in the world won’t mean a thing if the site’s soil is no good. With this in mind, Hendrikus Schraven, of the Issaquah, WA, landscaping company of the same name, turned his attention to the soil, and in the process created another company, Soil Dynamics.“Organics and soil amendments are very integral,” Schraven says. “There have been lots of landslides [in the area] in the past 10 years; all that’s left is hard glacier-till clays. A lot of these hillsides were hydroseeded, but that didn’t work; the seeds couldn’t penetrate the clay, which contains no microbial activity, no oxygen.“Revegetation is a process. What do you expect to happen on a site with road cuts and hard compaction? The native soils have been stripped off, but then the contractor adds chemicals, causing immediate runoff because the water has nowhere to go. How can such a site have root penetration or moisture retention?” Schraven believes the proper soil amendments are crucial for revegetation success. “We’re hoping to actually create the [natural] process, to bring grasslands and forests back quicker by adding moisture retention and living soil. Nature takes its time to revegetate; we don’t have the time to wait! This is not just a Band-Aid approach. First we use a soil/humus product indigenous to the area where we’re putting it, while adding compost tea. If the area will return to grassland, we’ll add more bacteria; if the area will be covered in conifers, we’ll add more fungal material-whatever the site needs.”
Blowing topsoil material onto a site
The right soil medium allows rapid root growth.Schraven uses a compost tea brewer to develop the beneficial microbes needed. “We insert a basket of beneficial compost-there are 10,000 to 30,000 microbes in there to begin with-and after 24 hours in the machine we get a tea that has over a billion microbes in it. We’re merely speeding up a natural process.” He uses the topsoil mixture he developed, known as EssentialSoil, in all his revegetation projects.“The soil depth we add depends upon the subsoil conditions,” Schraven reports. “It can be from six to 12, up to 18 to 24 inches, depending on the site. We also install earthworms in all sites. Burrowing worms will take organic matter down with them while they also excrete nutrition for plants. Does our process cost more at first? Perhaps, but it’s cheaper in the long run because we’ve restored beneficial elements to the site. If you don’t do this, noxious weeds will come back; so if you don’t want them there, you must do the right thing in the first place.”Many of the slopes needing work were too steep for equipment or even manual labor access; some slopes had to be scaled by employees wearing climbing gear. “I was told it wasn’t possible, so I basically invented the pneumatic equipment to blow my product onto the slopes. Sometimes we need up to 600 or 700 feet of tubing to get the job done. When we blow the soil on, we inoculate the top layer with seed. If the site permits, though, we also apply EssentialSoil by conveyor, and then we hydroseed,” Schraven explains.Depending on the climate, the “best” time to revegetate is, according to Schraven, “any time irrigation is available. If you’re working on a slope in the approaching winter months, just let the soil sit there and seed it later. Spring rains are what you largely depend on to get the seeds and root systems established, so you’ll have a blanket of grass established for the summer months.”Although the rainy Puget Sound climate can be a challenge, Schraven notes, “Even once when we got a downpour, the soil stayed put. In late September we hydroseeded, and by December we had 6 inches of root growth.” He’s now working with firms in other parts of the country, teaching the erosion control process he has developed. “In June I was consulting with a New York firm that’s working to make Battery Park a completely organic ball field. At present, they’re dependent on chemical-based maintenance. Plus, because of the sandy soil, the site needs lots of water-washing the chemicals right through! Layers of EssentialSoil could help produce a grass mat with a 24-inch root layer in six months, cutting irrigation a great deal. Even during droughts, the grass will get moisture, so we’re trying to determine if we can actually do this.”After 30 years in the business, Schraven continues his research into understanding soil. “We know more about our galaxy than the soil we walk on,” he remarks wistfully.
