Patience required: Growing Native Trees from Seed

By Laurie Casey
The Morton Arboretum

By now, your seed-grown tomatoes are done, your peppers are picked, your marigolds are browning around the edges. Maybe you’ve collected the seeds and plan to start again next spring. But consider planting something with more staying power…like a native tree.

Though it costs a little time and plenty of patience, planting a native tree from seed is an economical way to grow a beautiful tree. And there’s great personal satisfaction, too.

“It’s fun to grow a tree from seed, knowing you had a hand in starting it,” said Pete Linsner, manager of plant production at The Morton Arboretum, who teaches classes on growing plants from seeds. “Native trees are ideal because they’ve adapted to our climate. Plus, growing them is a way to expand their numbers, which continually shrink as urban sprawl uses up more and more open space.”

You won’t find native tree seeds in those little packets at the supermarket. You’ll have to do some hunting. Groups like Wild Ones local chapters (www.for-wild.org) host native plant seed exchanges in November. Or you can collect seeds from living trees.

Most native trees produce seeds between late August and early November. Pick a dozen or two seeds when they start to fall off or when ripening fruit changes to drab, dark colors. If you pick them too soon, they won’t sprout.

Next you’ll have to prepare seeds. “It’s not rocket science,” said Kunso Kim, Arboretum assistant director of collections who teaches a “Searching for Seeds” class this fall. “The key is to mimic the seasonal process and fool them that it’s winter.”

Seeds from Ohio buckeye, pawpaw, pecan, shagbark hickory, black walnut, and sugar maple like a cold period, whether produced by mother nature or your fridge.

First rinse the seeds and wash away any fruit pulp. Set out to dry for a day or two. Seeds with very hard coats (they don’t crack easily, even if you step on them), like pawpaw, need to be roughed up with course sandpaper.

Mix a handful of milled sphagnum moss, which naturally resists mold, with an equal amount of vermiculite (both are available at most garden centers). Place the mixture in a small, sealable plastic bag. Sand or a paper towel works too. Moisten the contents just enough so no water drips out when squeezed. Poke a few pinholes in the bag. Add the seeds, seal the bag and put in the fridge crisper drawer until spring.

Pagoda dogwood, common elderberry and some others need a month-long warm period before the refrigerator “winter.” Mix seeds with the moist sphagnum moss-vermiculite, and place the bag on top of the refrigerator to get fluctuating warm temperatures. If mold develops, open the bag for a few days. In a month or two move the bag inside the fridge.

Come spring, plant the seeds in a container of potting soil and put by a drafty window. With some nurturing, years from now your little seedling can be a meaningful, long-lasting feature of your home landscape.

Glad You Asked

Q. Where can I look for native tree seeds?
A. Collect seeds within a 90-mile radius of your home, Linsner advises. Those trees will likely be more adapted to our soil and weather. But get permission from owners before entering private land. And never collect seeds from county, state and federal preserves and parks—it’s illegal.

Q. Can I just plant seeds in the ground in the fall?
A. Bring seeds inside to increase the odds of sprouting. Critters will eat or carry off most seeds they can find. And many seeds are not viable. Honey-locust seeds are pretty easy to sow directly in the ground in the fall, as are Kentucky coffeetree, redbud, linden and sycamore.

At the Arboretum
Learn how to adorn your home with fall floral creations in the latest styles, from French Country to Urban Edgy, at “Fabulous Florals: New Designs for a New Generation” Tuesday, October 14, 1:30-3:30 at Thornhill Education Center. Fee is $30 (discount for members.) Registration now open. Call (630) 719-2468 or visit www.mortonarb.org.

Laurie Casey is a staff writer at The Morton Arboretum.