Cool Season Primer

by Sarah West


When we think of vegetable gardening, it is under a wide-brimmed hat, sun on bare arms, baskets of green beans and tomatoes marching to the kitchen, unstoppable zucchini. We think of summer. Somehow, the thought of growing food seems only to germinate in most of our minds once the sun makes its first (and brief!) spring appearances. Dreams of bounty turn feverish and we can’t wait to put something in the dirt. Once we’ve mastered the art of tomato pruning, wrestled the beans onto the trellis and found ways to keep the neighborhood cats from their new favorite litter box, we wait for the flood of produce, then take the winter off to recover, it seems, from a summer of fresh, homegrown vegetables.

It doesn’t have to be that way. Ambitious vegetable gardeners of our region keep growing right through to the holidays and beyond. In our climate, it’s not only possible, but ideal for certain crops. Besides the obvious luxury of having fresh produce from your garden months after the last tomato ripened is a lesser known bonus: most fall vegetables that experience repeated frosts get sweeter and more flavorful. Vegetables that are capable of surviving cold dips in temperature do so by producing extra sugars that are distributed throughout the plant as antifreeze. The more frosts the plant experiences, the more sugars it produces. Thus, vegetables that spend the cold season in your garden develop a depth of flavor unmatched by their summer counterparts.

Year-round gardening is a bit of a misnomer. The implication that one can actively garden twelve months out of the year is a claim plant physiology does not support. To grow and thrive, all plants rely on some ideal combination of three components: light, water and temperature. Surprisingly, with cool season growing it is the component of light, not temperature, that we must give our closest attention. Twelve months of growing is not possible here simply because in winter our days are short and do not provide enough light for plants to actively grow. Most annual vegetables require ten hours of daylight to put on new growth. Without it, they sit and wait, a living pantry. So here’s the trick: plant your cool season crops early enough that they reach a harvestable size before day length dips below ten hours. In Portland, the last day we have ten hours of light hits around November 3rd, the first day it returns is approximately February 6th.

The biggest challenge of year-round gardening is timing. In the heat of July and August, not long after tucking in those peppers and tomatoes, you have to start thinking about summer’s wane, the shrinking of daylight, the inevitable chill. Just as you are settling into cool drinks and dinner hot off the grill, autumn comes knocking. It took me three year’s worth of attempts to finally plant early enough, simply because I was so distracted by summer gardening and recreation.

The basic technique is to count backwards.  Vegetables I know I will want to harvest in winter and early spring (kale, carrots, purple sprouting broccoli) need to be approaching maturity by November 3rd.  This often means starting seeds in early August or getting transplants in the ground by early September.  Vegetables for fall harvest (beets, parsnips, salad greens) need to be started even earlier, usually the first half of July.  Most seed catalogs provide a number of days to maturity.  While this number is rarely accurate in our cool, damp springs, it comes closer to ringing true in high summer.  I begin with the date I would theoretically like to harvest and count backwards to when I should be starting my seeds.  Plants started in July will mature more quickly than those started in March, and they will also need to be protected from the heat.  I only direct sow what I have to—carrots, namely—and start the rest in pots of soil mix that I keep in part-shade until they have developed a strong enough root system to fare better in full sun.

Certainly, good planning and preparation can have big payoffs. That three-month interim of short days without growth could become a time of continuous harvest. And the bonus is that most weeds won’t grow without ten hours of light either. Once established, it is a nearly effortless garden: self-watering, weeds whose pace you can keep up with, just about free of pests (save those persistent slugs).

I can’t promise, however, that it won’t rain on you, so I’d swap the wide-brimmed hat for a jacket with taped seams.

(Originally published in the Hillsdale Farmers’ Market newsletter, The Grapevine, July 12, 2012)