WICHE: Propagating trees from seed

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By Jeneen Wiche

Some plants are prolific, and some are not.

Dandelion seeds float through the air and disperses far and wide in spring or summer. Hundreds of tiny seeds burst from the spent blooms of cleome as a sphinx moth feeds at dusk. And you can just walk past some hairy cress, and millions of seed burst forth from the draft!

Woody plants seem to be a bit more elusive. I have never seen a Serbian spruce spring forth from a fallen cone or an apple tree emerge from rotten fruit beneath the canopy.

Starting woody plants from seed can be a bit trickier.           

We have tried to propagate a variety of woody plants from seed. Some are actually pretty easy.

My husband has planted several yellow buckeye started from seed. Redbuds, oaks and silky dogwoods pop up in the pine grove all the time on their own. The paw paws that we tried to propagate, on the other hand, languished on the veranda of the barn, nothing happened.

The more we learn about the plants we want to propagate, the more successful we manage to be. The bottom line is this: mimic the native environment and the nuances of the seasons as closely as you can when you try to start woody plants from seed, they require specific treatment to achieve germination.

There are different ways “seed” manifests itself: cones, drupes, nuts, pomes, samara and globular head, for instance.

This time of the year most seed has matured and is ripe and ready for collecting. Once collected the real challenge begins: know what you have and how you should treat it.

There are four categories of processing and pre-storage for seeds of woody plant species. Some seeds need to be dried for extraction and storage (sweetgum, sycamore, ash, maple); some need to stay moist in storage (these are referred to as recalcitrant seeds including buckeye, oaks); seeds that must be kept moist during extraction and then dry during storage; and those that can be planted right away in the fall or stored under moist conditions until spring (hickory, white oak, walnut). This last group is the easiest, of course.

For the average gardener that just wants to play around with trying to start some woody plants from seed your refrigerator becomes a useful tool.

Let’s say you want to start some paw paws from seed (like we do). The fruit is harvested ripe from the tree and the seeds are extracted and cleaned.

Pawpaw researcher Kirk Pomper has determined that seed must be kept moist and a chilling period of at least 100 days is necessary for germination.

Store the cleaned seed in a baggy full of moist peat moss in the refrigerator. Do not let the moist seed freeze (ice crystals will damage the seed tissue). After the 100-day period of stratification plant the pawpaw seeds in tall pots so a deep taproot will form.

Depending on the type of plant you want to start you may need to do a little research into the requirements for germination but in the meantime you can get your feet wet using Mother Nature as your staging area. Collect a nut from an oak, a drupe from a dogwood or a legume from a redbud and cover them with some soil in the garden. Protect the area with a wire basket to keep critters from eating the seed as a mid-winter snack and see what emerges next spring.