The season turns again, September arrives in a flurry of changeable weather and all the plant world resonates with the arousing feeling of the lengthening nights. Plants get their information from the change in the duration of the nights, not from the absolute length but from the speed of change. These shortening days mean longer nights, which stimulates changes in the metabolism of the trees, shrubs and flowering perennials that we use for our landscapes.
David Lendrum is a master gardener and owner of Landscape Alaska. Responses or questions can be sent to www.landscapealaska.com.
The responses vary in intensity according to the origin of the plants. Those from more northern or extremely southern places, those with greater seasonal change, will respond more quickly than those from more temperate latitudes. Hybrid responses will vary across populations just like the range of colors and sizes will. Some will exhibit the exact responses of one parent, some of the other, most will show a mixture or range in gradation.
The easiest place to see this is in leaf coloring; some are in full fall color right now, some will wait until mid-October, and some will never show color, but just turn brown and drop. There are even trees that began turning color and shedding leaves a month ago.
It is harder to tell from aboveground, but there are root responses, too. The roots are growing like mad right now. Thats why so many people are planting their trees and shrubs during this relatively pleasant time of the year. The soils are drier and more workable now than in the early spring, so it is nicer to plant now, and the plants will settle in happily during the next two or three months.
Leaves may slowly show the colors of autumn, but even after they have sailed off the twigs and branches, roots are still active. These permanent parts of the plants are hard at work right now, pushing along through the soil making contact and engaging more of the soil network each day. The bigger roots grow smaller ones, which put out tinier ones. The roots that are actually interfacing with soil and with all other organisms in the soil are smaller than the hairs on our heads.
These root hairs are the growing portion of plants, they poke about absorbing moisture through their cell walls and taking along with the water anything that is dissolved in it. It's a good time for a fat-full meal before the long season of famine.
We are planting almost every day at this time of year, placing soil into beds and arranging trees and shrubs into sturdy frameworks of yards and gardens that will provide the outside settings for lives and activities. We always make sure to have sufficient nutrients in the planting area for these questing roots to feed on during fall and winter.
This is not a high-nitrogen meal; the nitrogen we provide now is in slow release form and in composted manures. The plants should not be boosted back into abundant growth - which would result in soft tissues vulnerable to winter damage - but rather fed for endurance and reserves.
The most recent research tells us that the proteins used for early spring growth are not those taken up by the roots in the late summer; they are those that were stored in the leaves and bark during the active growth season. These are withdrawn from the leaf tissue and stored in the bark and buds over the winter, and are the first used for the revival of the leaves in the new season.
This has a practical application: It is possible to piggyback onto this natural system and dramatically increase the level of leaf protein by spraying liquid fertilizers on the leaves and bark of the trees and shrubs in late summer. This fertilizer can be absorbed directly by the leaves and used in he manufacture of the sugars that are the life force of the plants.
This means that we are miles ahead if we use something like Miracle Grow or some other formulation for the next couple of months.
Planting the trees and shrubs now with good soil and enough slow-release nutrients is the first step, and feeding them with a hose-end sprayer during their period of establishment will give the best results of the year. Roses, spiraeas, birch trees and apples will all benefit from this technique. Hardy perennials will love it too.
This really is the season for planting, both for us and for them.