Spring seems pretty far off here in the North, especially with wildly fluctuating temperatures, snow, ice and even rain. But you can have a little green by tricking some woody plants into thinking that it’s time to grow. “Forcing” is a term used to describe the process of encouraging a plant to bloom out of season. This is often done when your ground froze, and you didn’t get all your bulbs planted in the fall. If those bulbs are not desiccated, just pot them up, water, then store in the dark in a cool greenhouse, garage or crawl space and wait a couple months for them to bloom. Homegrown Spring!
Spring-flowering trees and shrubs work well for forcing, as these plants develop their flower buds during the fall of the previous year. Simply cut branches of flowering plants and place the cut stems in water in a warm environment to encourage flower or leaf buds to open. Flowering branches such as Forsythia, Rose Tree of China (Prunus triloba) and apples may reward you with their blooms, but even non-flowering willows, alders, and birch, etc. will show off their leaves, just when you need to see some green.
For the smell of Spring, cut some Cottonwood branches. There are two relevant species found in Alaska, Populus balsamifera L. ssp. balsamifera (balsam poplar) and Populus balsamifera L. ssp. trichocarpa (black cottonwood). Balsam poplar is the northernmost hardwood in North America. As the sticky buds begin to open, you will get the smell of springtime in Alaska. The species (Populus balsamifera) is used to make a North American version of Balm of Gilead, a fragrant oil with medicinal benefits. Although cottonwoods have many detractors, due to the fluffy “cotton” and the tendency to drop branches, they can grow to an impressive size and have other benefits. Here’s a video about cottonwoods that was filmed in Anchorage.
When collecting any branches for forcing, prune them back to an outward-facing bud or cut back to a natural branch point. Look for branches that need removal due to crowding or inward, crossing growth. In other words, do your pruning now and into Spring. For wild-collected plants this is not critical, but for your ornamentals in your yard, it’s a good idea to use proper pruning techniques. In the wild, many branches have already been moose-pruned.
Bring the branches indoors and make a fresh, diagonal cut at the base of the branch before arranging cuttings in a vase. Remove any buds that will be under water. Growth can take several days or even weeks to open, depending upon the species. Keep the water fresh by replacing every few days. You can combine woody cuttings with evergreen branches or create colorful arrangements using stems of red or yellow-twig dogwood or red-berried Mountain Ash (Sorbus species).
Some species such as Willows and Cottonwoods will even grow roots. This is why they are often used for streambank restoration. Cuttings are collected from dormant plants. These are basically just stuck in the ground along a stream bank to control erosion and degradation. These cuttings do not have leaves when planted but will soon green up.
You may have seen Curly Willow (Salix matsudana) used in floral bouquets, begins to root in a vase.
So why does this rooting trick work with these plants? There are two substances found within the Salix (Willow) genus, namely, indolebutyric acid (IBA) and salicylic acid (SA). IBA is a plant hormone that stimulates root growth. It is present in high concentrations in the growing tips of willow branches.
Another use of Willow cuttings is making Willow Water. By cutting the actively growing parts of a willow branch, and soaking them in water, you can get enough IBA to leach out into the water. And that makes “willow water” for stimulating root growth in cuttings and seedlings. Willow water is a homemade plant rooting growth hormone.
How make Willow Water:
- Collect young willow stems, those with yellow or green in color. By the way, willow and aspen can photosynthesize in the winter because the greenish-yellow of the bark layer carries out photosynthesis. In winter, when other deciduous trees are mostly dormant, these trees are able to keep producing sugar for energy.
- Remove the leaves, if present.
- Cut the stems into 1–2 inch segments. You can crush them with a hammer to speed up the leaching of the IBA. Add to a jar or vase.
- Add boiling water and let steep for a day or two. When cool, strain into another container for rooting your cuttings, or use to water seedlings.