Turning to the light

Photo by Susan Safford

We are a week into the new year, 2016, and already I am happy to report daylight has increased by six minutes at sunset. Time of sunrise remains steady through the weekend, when it occurs one minute earlier. I possess this welcome information thanks to my UMass Garden Calendar, produced by UMass Extension, which contains other useful garden info as well.

Many natural processes are set in motion by light, in plants as well as warm-blooded creatures, even humans. Indeed, my Christmas present “Dictionary of Science for Gardeners” (Timber Press; by the way, a wonderful gift for would-be garden geeks) contains a page and a half of entries containing the prefix “photo-,” from photoblastic to phototropism, while my dictionary contains four columns of words that contain it, from the Greek, “phos,” “phot-,” light.

In humans the light-sensitive glands, or organs, include pineal, pituitary, and the eyes, about whose complex functions and interactions contemporary researchers are learning more and more all the time. Our biological, hormonal, circadian, and seasonal rhythms are mediated in response to light, which gives us a fundamental commonality with plants. Some plants, just like some humans, prefer to go dormant in winter, but as light levels increase find themselves reviving.

Now, however, unseasonably mild temperatures have caused many plants to respond and awaken prematurely. Down-Island towns are full of reports of forsythias, ornamental cherries, and daphnes in bloom; the illustration shows a flowering cherry at the Field Gallery in West Tisbury.

Many ornamentals we like and plant require only a short period of cold in order to ready for the coming season. The danger is, Will later, fatally severe cold arrive after some have gone too far along in the process of breaking dormancy?

Matt Mattus, at his popular website “Growing with Plants,” (bit.ly/GardenNotes) writes extensively about the dangers and causes in the post “Will our unseasonably warm winter damage our plants?” and points out that many of the plants in danger, through prematurely budding up in his Worcester-area garden, are primarily Asian or European.

Natives seem more circumspect about breaking dormancy. He writes, “Native plants respond to day length more than they do temperature, so most of our wild plants will be safe ….”

A protective strategy for exotics prone to break dormancy prematurely is to deliberately plant them in sites that are shaded or cold, such as north sides of structures, in order to deprive them of the protected warmth a cozier site could provide, and thus retard their response to early warm spells.

Where there is concern about cold hardiness, it is worth remembering the protective quality of old wood for vulnerable plants. A helpful principle for gardeners is to leave old wood on plants that are apparently in need of cleanup, in order to take advantage of the fact that leaving dead flowers, seed, or fruit on the plant means it will do its best to protect them for purposes of reproduction. The classic example is leaving deadheads on mophead hydrangeas.

Although not the high-priced investment of trees or shrubs, perennials too are at risk from unseasonably warm weather, and the freezing and thawing that causes heaving and root breakage. The hemerocallis and narcissus tips now showing will ride out most variable conditions; shade them with evergreen branches. Alpines and Mediterranean-origin plants require good if not perfect drainage; add grit or peastone to planting holes; site in dry locations.

More light means …

… thinking about ordering and starting seeds. Most of the seed catalogues I prefer arrived in the mail before Thanksgiving. January is seed-starting time for plants that take a long time to mature in our climate. (Which climate? It is changing daily.) Really helpful tools are grow lights and heat mats.

Seeds that you might think about sowing in January include leek, onion, celery, artichoke, kitchen herbs, lobularia (sweet alyssum), corn salad, and lettuce. Seed of annual poppy, such as the coral ones of unknown variety my daughter saved and gave me for Christmas, are scattered outdoors now: They are photoblastic (seeds that germinate in response to a stimulus from light), as are lettuce and celery, and need no soil covering.

Read seed catalogues carefully; the fine print is full of information. A couple of websites are also helpful about seed-sowing schedules for the vegetable garden: Gardener’s Supply Co. and GrowVeg.com. The main point is to refrain from sowing fast-growing plants too early: Unless you have extensive cold frames or hoop houses, you will create plant gridlock, and maybe vernalization.

Vernalization is what happens when plants receive enough cold to make them “think” they have gone through a seasonal growth cycle and can proceed to flower, set seed, and die: Vernalization can work for or against you. In some, such as Swiss chard and cole crops, it contributes to unwelcome bolting. In others, such as artichokes, it is what may enable you to get a crop before winter.

Light up the garden

The planting of evergreens with golden foliage is a trompe-l’oeil sleight of hand that British gardeners have long employed in the dreariness of their northern, rainy landscapes; these plants trick the eye into thinking it is seeing sunshine on a cloudy day.

The desire for such a bright spot has been growing in me recently, with the difficulty being simply choosing among the many plants and cultivars that are available, and whose numbers indicate how desirable a feature such a plant can be.

Do I want a candle-flame form, such as Chamaecyparis pisifera ‘Filifera Aurea’, or C. obtusa ‘Crippsii’? Or maybe I want a muffin or mound, such as the ‘Gold Mops’ or ‘Gold King’ cultivars. Deer-resistant? The eventual choice should backdrop the colorful bloodtwig dogwoods we planted last spring, and then — oh boy! — that spot will go technicolor.