An innovative approach to hardwood regeneration
Establishing hardwood trees by sowing seed is a relatively new method that has several advantages over traditional planting of seedlings.
Advantages over seedling planting
- Better and quicker establishment: Direct seeding establishes thousands of seedlings per acre rather than hundreds per acre with traditional planting. Trees reach "crown closure" and begin shading out grass and weed competition earlier. Follow-up grass and weed control typically only needs to be done for two years after seeding, instead of eight to 12 years with planting.
- Higher quality timber: Greater density of seedlings forces trees to grow straighter due to side competition from nearby stems. Competition decreases pruning needs and produces higher quality hardwood saw logs.
- Better use of natural selection: Trees best suited to a particular site will dominate because of large numbers of seed and species.
- Better adaptation to variations in site conditions: Small variances in site conditions aren't planned for when planting seedlings. With direct seeding, species and specimens best suited will take over in each area.
- More natural appearance: Direct seeding is a much closer approximation of mother nature's hardwood establishment method than seedling planting in rows.
- Better ability to withstand animal predation: Animals such as deer, while still causing damage by browsing, will be less likely to devastate a direct seeding than a traditional seedling plantation due to far greater stems per acre.
Potential disadvantages or problems with direct seeding
- Higher initial cost: Establishing seeds may be somewhat higher than planting seedlings ($500/ acre vs. $350/ acre average). Keep in mind, however, that part of the higher cost can often be offset by government cost-share assistance or by collecting some seed yourself or doing your own tillage. Follow-up care costs will be compressed into the first two to three years, but may total a bit less than with seedling planting, due to earlier crown closure.
- Inconsistent seed availability: Seed for inconsistent seed-producing trees like red oak may not be available every year. Some years, supplemental seedling planting or delay of direct seeding may be necessary for oaks or other species.
- Site accessibility: Direct seeding requires access by site preparation machinery, so some very steep sites and sites already wooded do not lend themselves to establishment by direct seeding. Seedlings will need to continue as the regeneration method of choice for these sites.
Direct seeding methods
Sites covered by grass must be clipped in mid August to early September. The grass is then allowed to grow back several inches and is killed with a broadcast treatment of herbicide. After dieback, the field must be tilled black. As an alternative, discing a number of times through the summer is best. If a site is in an annual crop such as oats, corn. or soybeans, a light discing is all that is necessary, unless field was "no-till" drilled, then a heavy discing or chisel plowing followed by discing. In either case, grass waterways and contour strips should be left to minimize erosion. Apply a preemergent herbicide in fall or spring for annual grass control. Contact local forester for advice.
Seed collection and storage:
Seed collection and storage is often more than a landowner can tackle alone. Knowledge of characteristics of many kinds of seed (ripening times, moisture and storage requirements, etc.) is a must. There are vendors who sell seed from experienced collectors. This is often the best method for landowners to obtain viable, high-quality seed. If landowners wish to collect seed on their own, they should contact their local forester for species specific handling and storage advice.
Depending on your site, the following species and rates are commonly recommended. Your forester can adjust species and rates as needed for your particular project:
Bushels Per Acre
Pounds Per Acre
1 to 2
1/4 to 1/2 pound
1/4 to 1
1/4 to 1/2 pound
1/2 to 1
5 to 10 pounds
10 to 20
Shagbark hickory (within its range)
1/4 to 1/2
Swamp White oak (lowland sites)
1/4 to 1/2
Grey or red-osier dogwood
Ash (green, white, black)
1/4 to 1
1/4 to 1/2
First, large seed - acorns, walnuts, hickory nuts—are typically broadcast with a fertilizer spreader over the entire field and then disced in to a depth of 1 to 2 inches. The lighter seed—ash, maple, cherry (and shrubs if any)—is broadcast and dragged in lightly.
Controlling grass and weed competition until seedlings reach "crown closure" (which often happens in year 3) is crucial to the success of any seeding project. If weeds are not controlled, tree seedlings will be out competed for moisture and sunlight. Typically a pre- or post-emergent herbicide is used early in the first season and a post-emergent herbicide is used later in the first year. If broadleaf weeds become a problem in year one, mow the area high, above the top of tree seedlings. A pre- or post-emergent herbicide application will be needed in year two. The area will need to be scouted often in order to determine weed control needs. Contact your local forester for specific herbicide recommendations.
Many sites would benefit from the addition of some understory shrubs for diversity and wildlife habitat. Grey and red-osier dogwood, chokecherry, highbush cranberry, wild plum, nannyberry, blackberry elder, and American and beaked hazel are some common shrub species in much of Minnesota. Your forester will know which species will fit your site. Shrubs in direct seeding are relatively untried and are subject to failures due to seed handling problems and herbicide damage until more is known. Addition of shrubs will also raise costs. Establishing hardwood trees by sowing seed is a relatively new method that has several advantages over traditional planting of seedlings.