This winter’s cold is most evident on bamboo. Clumps of tawny dead leaves, still attached to the canes, stare out from among the trunks and stems of dormant trees and shrubs. I hadn’t realized that bamboo was so widely planted. The depth of cold isn’t what killed the canes and leaves; it was the duration of cold. Seventy miles south of here, leaves of yellow groove bamboo, Phyllostachys aureosulcata – among the most cold-hardy of the thick-caned bamboos – typically stay green and fresh all winter, but even they’ve been killed.
No, the plants aren’t dead – just their canes and leaves. Warm weather will coax new shoots from the roots, shoots that will push skyward rapidly. I’ve measured as much as six inches of elongation per day. The record for bamboo growth (not around here, of course) is almost three feet in one day!
That little tidbit comes from Bamboo, by Susanne Lucas, a beautiful new book – in its binding, photographs and clear writing – that provides an introduction to the culture, horticulture and myriad uses of bamboo. Read it and you also will want to grow bamboo. For even more in-depth information on bamboo botany, culture and uses, I turn to the no-frills book The Book of Bamboo by David Farrelly.
Once bamboo shoots stop their skyward ascent, the walls of the canes begin to thicken. Canes that survive winter with green leaves intact don’t grow any taller in subsequent years. Cane diameters remain constant as they thicken within, in so doing becoming more useful for stakes, fencing, gates and structures in the garden and beyond. Eventually, whether winter temperatures are frigid or mild, a cane dies.
Dead canes, whether from age or from winter cold, eventually need to be removed to keep a grove looking spry. For my planting, I decided on the dramatic approach, cutting virtually the whole planting to the ground. I used a lopper, attacking canes one at a time, then a machete to remove side shoots with leaves from canes worth saving – not an easy job, but one that yielded an abundance of useful canes. Now, what to do with my stockpile?
As winter freezes have segued into capricious spring frosts, seedlings need to be readied for the great outdoors. In a greenhouse, on a windowsill or beneath fluorescent lights, these plants lead a coddled life. Outside, life is tougher: Temperatures swing 50 degrees in a 24-hour period, winds whip tender leaves and intense sunlight beats down.
What these plants need is a couple of weeks of acclimatization: “hardening off.” Not too quickly and not too severely, though, or leaves could burn or flowers could appear prematurely; a plant could even die from shock. The thing to do is to find some cozy spot outdoors for the transplants: a spot that is sheltered from wind and receives sun for only part of the day, or else dappled sun all day. After about a week, the plants are ready to be moved to a more exposed location – one that just takes the edge off gusty winds and broiling sun. A week at this second location and plants are ready to be planted out in their permanent homes.
The kinds of changes that hardening-off induces in coddled seedlings depends on the nature of the seedlings themselves. Seedlings of cabbage, lettuce, snapdragons, pansies and other plants that can eventually laugh off cold even below freezing develop a tolerance for cold by building up sugars in their cells. Gradual exposure to more intense light also thickens cell walls, fibers and cuticles on both existing and new leaves. With increasing light exposure, chloroplasts – the green, light-trapping energy factories in leaves – move around and align themselves in such a way that the leaves turn darker green. And the leaves’ stomatal pores, through which water is lost and carbon dioxide and oxygen are exchanged, become more quickly able to open and close in response to changing conditions.
Cold-tender plants such as tomatoes, marigolds and zinnias suffer at temperatures even above freezing. With these plants, chilling injury causes changes in plant membranes that interfere with photosynthesis and damaging toxins build up in leaves. Hardening-off makes these plants better able to repair and prevent such damage. But temperatures that still drop below freezing mean that it’s still too early to begin hardening off cold-tender plants. Anyway, they’re still too small. Wait a month.
During the two weeks of hardening off any plant, growth slows and the plant becomes stockier. This is good; it indicates that a transplant is ready to face the world.
It’s time to prune trees and shrubs! I will be hosting a Pruning Workshop at my New Paltz farmden on April 27 from 2 to 5:30 p.m. Learn the tools of the trade and how plants respond to pruning, and see hands-on pruning of filberts, blueberries, lilacs and other plants. Space is limited, so preregistration is necessary. The cost is $55 per person. To register, e-mail email@example.com or call (845) 255-0417.
From April 23 to 26, Cornell Cooperative Extension of Ulster County (CCEUC) master gardeners are clearing out their entire inventory of berry, vegetable and tree seedlings, as well as herbs, flowers and heirloom seeds! Take advantage of a wide variety of plantings including blueberries, raspberries and strawberries, a great assortment of heirloom seeds, hardy vegetables like asparagus and horseradish and a wonderful array of evergreen seedlings including deer-resistant ten-packs of three-year-old bare-root seedlings of Colorado blue, Norway and white spruce. For more information about specific dates, locations and plants available, go to www.cceulster.org or call (845) 340-3990, extension 332.
Any gardening questions? E-mail Lee at firstname.lastname@example.org and he’ll try answering them directly or in his Almanac Weekly column. To read Lee’s previous “Gardener’s Notebook” columns, go to HudsonValleyAlmanacWeekly.com. You can also visit Lee’s garden at www.leereich.blogspot.com and check out his instructional videos at www.youtube.com/leereichfarmden. For more on local homes and gardens, go to Ulster Publishing’s www.HomeHudsonValley.com.