As the cold outbreak has developed over the weekend, the forecast now for some parts of the coast are for lows down to -7 to -12oC (10-20oF) by Wednesday night. This is much, much colder than our usual Arctic outbreak and well into damaging range for many of our coastal gardens plants. There doesn’t appear to be any significant snowfall in the forecast that would provide valuable insulation. So today, beef up your insulation on all above-ground vegetables, even the hardiest ones we don’t usually worry about; kale, hardy leeks, Brussels sprouts, as they would be damaged at these lows. If possible, pile on more leaf mulch around plants and then cover with tarps, plastic sheets, old blankets, etc.
Unfortunately, because it has been so mild this winter, some plants are at greater risk of cold injury now because they have started to grow. Artichokes are especially vulnerable so pile the mulch back over the crowns of plants and add an extra covering (e.g., tarp or very large pot turned over the crown). Fluff up mulch and cover strawberry plants to prevent frozen soil from heaving up the crowns.
If you have a lemon or lime tree outdoors keeping warm under a cover a with heating cable or Christmas lights, harvest any ripe fruit today (note that lemons can be ripe without turning yellow; I picked dozens of ripe lemons from my tree yesterday). Put extra covers over the tree to insulate it: at these temperature, the heating system may not be enough to prevent fruit and buds from being frosted.
Don’t forget you irrigation system, either, which might have valves or other parts that are vulnerable to freezing. If you have fruit or vegetables (or dahlia tubers, etc.) stored in outbuildings, bring them indoors for the duration of the cold snap. Bring indoors potted plants that usually can stay out or at least drag them against the house and cover them.
OKAY, folks, get out there now and do what you can for your garden!
Pruning and Starting Seeds
With a few nights of well below freezing temperatures forecast for next week be ready to cover leafy greens with tarps to prevent cold injury. At the moment, some parts of the region have a -5 to -9oC forecast for a couple of nights in mid-week. When I hear a -5 forecast, that is my warning to cover lettuce, spinach, chard, broccoli and cauliflower because it is likely to be colder at my elevation.
With cold weather coming I want to make sure I am not harvesting crops while they are frozen (they wilt to mush when they thaw out in your kitchen). Tomorrow I plan to dig a bucket of carrots and other roots, behead a cabbage and pick enough Brussels sprouts and salad greens to fill the fridge for the duration of the cold spell. Frozen plants that look wilted and ruined will perk up and look normal again once they warm up. Note: While hardy cabbages tolerate freezing solid out in the garden, it can take a week for a frozen head to thaw entirely once temperatures rise above freezing so give them time to recover.
Pruning: This is the month to finish up pruning fruit trees, berry bushes, grapes and kiwi. Fruit buds are already swelling on the earliest blooming trees (peaches, cherries) so finish pruning those sooner rather than later. If you had sticky trunk bands on trees to catch winter moth females as they crawl up the tree to prevent from laying eggs further up the tree, you can take those down later this month.
I am often asked whether sap running from pruning cuts on grapevines weakens the plant. It is common to see the vines ‘bleeding’, but it doesn’t mean they are suffering any harm. It is a normal occurrence as the roots start to grow and take up water. Apparently, it may even have a beneficial effect by pushing out air bubbles that may have formed in the internal channels (xylem) that carry water from the roots to other parts of the plant.
Starting Seeds: This is the month to start seeds of the vegetables that take the longest to develop, if you can provide good growing conditions (bright lighting, warm temperatures) and management (don’t overwater or let plants get rootbound from being held too long in small pots). I went into seed starting methods so thoroughly in a previous message that I will just refer you to that Feb. 28, 2019 message.
Often new gardeners try to start seeds too early, which can result in plants that are stunted from being held under poor conditions or in the same pots for too long. What you want to achieve is a seedling that has grown quickly under the best possible conditions and never suffered a check in growth, whether from cool weather or crowded roots. If you misjudge the weather and have to hold seedlings longer than planned, move them into larger pots so they can continue growing without setback. Seedlings that experience a period of restricted growth never produce as well as plants that were not stressed during their early development.
When to start seeds really depends on how much space you have with the optimum growing conditions for seedlings. Start seeds later if you don’t have a lot of space for seedlings under grow lights or in a warm greenhouse and will be moving trays of seedlings to a coldframe or unheated greenhouse during the day (and trundling them back indoors at night). Conditions on cloudy days will be warmer later and it saves a few weeks of labour. For tomatoes, that could mean waiting until the end of March to start seeds. But if you have a really skookum seedling setup (excellent grow lights or a heated greenhouse) or going to plant the tomatoes in a greenhouse for the season, you could start seeds today.
Here is a general guide on timing for seed starting:
Feb: Celery, celeriac. These very tiny seeds take a long time to grow into a decent sized start. They are also among the very few vegetable seeds that need light to germinate so scatter seeds on the surface of the soil mix. I am not kidding about how small the seeds are: Don’t sneeze!
Feb-March: Leeks, onions from seed (not onion sets). I used to sow these in mid-February, but now wait to March 1 because I found there was no difference in yields from the later planting date.
March: Tomatoes, peppers, eggplant, sweet basil. Start them early in the month if you have a good seedling set up, end of the month is you have limited space or are using a coldframe to grow out the seedlings. This is also when to start early cabbage, broccoli or cauliflower if you are in a rush because you don’t have any in the garden this winter. Gardeners with hardy cabbage, winter broccoli and winter cauliflower growing now need not be in a hurry to start more since overwintered plants usually produce through May.
April: Zucchini & other squash, melons, cucumber; cabbage, broccoli, cauliflower.
May: Corn, beans. First plantings of these benefit from an early start indoors where they can germinate in warm conditions; later plantings, can be sown directly in the garden once the soil is warm enough (over 18oC/65oF)