With autumn foliage reaching its peak display of color, many homeowners and acreage owners may be thinking about adding a few trees to their landscapes. Collecting and germinating seeds can be an inexpensive and fun way to start trees. And it's easier than it might appear.
There are several tree species that reliably germinate, transplant fairly well in small sizes and are well-suited to Nebraska's climate. Some easy-to-grow species that are recommended by ReTree Nebraska include concolor fir, Kentucky coffeetree, northern catalpa, baldcypress and bur, chinkapin and English oak.
Sources for seed can be found all around, but the best sources are healthy-looking, mature trees that have seen – and survived – harsh Nebraska winters and scorching summers. There will assuredly be high-quality genes in those seeds.
In most cases, it's fine to collect seed from public parks and arboretums, but it's always a good idea to ask permission first. A good place to start is the Nebraska Statewide Arboretum, with over 90 affiliate sites across Nebraska listed at arboretum.unl.edu under "Affiliate Gardens."
What makes a good seed? There are many factors, but the most important are maturity and seed health. In general, a seed that easily separates from the tree is mature. Many nut trees in this area are ready in early October. Freshly fallen seeds may be OK to use, but watch out for immature (unfilled) or insect-eaten seeds and for signs of damage such as cracked hulls, weevil holes, soft spots or discoloration. A great way to test large seeds is to dump collected seeds into a bucket of water, wait a few minutes and then discard any floaters. The heavy seeds that sink to the bottom are most likely the healthiest. This works great for most acorns, buckeyes, pecans, hickories, magnolias, tuliptrees and Kentucky coffeetree.
Fleshy seeds, like black walnut, wild plum, dogwood and baldcypress, should be cleaned before planting or storage. Leaving the fruit to soften for several days after collecting will speed the process. An effective but messy method is to soak the fruit in a bucket for a week, then separate the pulpy mess from the hard seeds and rinse several times. Taken from experience, this is work best done outdoors! A note: black walnut pulp has a tendency to stain clothes, hands, tools and anything else it contacts a yellowish brown color, so take care when processing walnuts.
Once seeds have been collected and sorted, they must be stored properly. Some may tolerate long-term storage, but others must be planted right away and not allowed to dry out. When in doubt, consider Mother Nature. If a tree drops its seeds in fall, the seed will likely need a cold, moist treatment (called "stratification") of three or four months in order to germinate; in other words, it mimics a normal winter spent in the leaf litter and soil beneath a tree. Seeds that drop from a tree in spring will probably germinate right away. If intuition fails, another great source for information on treatment of seeds from many species is Michael Dirr's "Manual of Woody Landscape Plants," available at many public libraries.
When planting seeds, a good rule of thumb to follow is that the seed should be planted about twice as deep as the seed is thick. In other words, a half-inch acorn should be planted about an inch or so deep. After planting, it helps to lay chicken wire over the top to prevent squirrels and other hungry creatures from digging up and eating your future tree.
A handy method of getting stubborn seeds to germinate is to use an outdoor seed bunker – a wooden frame with hardware cloth on the bottom, filled with about 6 inches of soil and raised up from the ground on cinder blocks or legs to "air prune" the seedlings so they don't root into the soil beneath the bunker. As seedlings emerge over the next year or two, they can be transplanted to their final location.
Keep in mind that most plants transplant better when they are small and dormant. The more the roots are disturbed, the more "transplant shock" the tree will have. An obvious way to avoid this problem is to plant the seed in its final location – right in the ground. Many fine woodlots have been planted with nothing more than a dibbling stick (for making holes) and a sack of acorns (for making trees). Even if the goal is to plant just one tree, it's sure easier to dig a hole for an acorn than it is to dig a properly-sized hole for a balled-and-burlapped nursery tree!
After the seed has been gathered and germinated, and the seedling transplanted, mulched and watered, one more important step remains – protection from critters. Rabbits, deer and even squirrels can cause damage to buds, stems and bark of trees of all sizes, but small trees are especially susceptible. A cage that surrounds the tree – even over the top for smaller seedlings – is crucial to limit damage by hungry nibblers. Trunk protectors can stave off rabbits, but be careful to allow air circulation around the stem to prevent insects and fungi from wreaking havoc.
Many folks are put off by the notion of starting their own trees from seed, thinking that it will take generations to see a shade tree grow from a tiny nut. On the contrary, these trees may well catch up with and overtake trees that were put in by a tree spade; so don't wait for tomorrow – plant some seeds today!