{ Posts Tagged ‘fall’ }

Jack Frost comes to town

School is back in, the trees are changing color, and bugs are (attempting) to move inside: fall is unavoidably here. Some of you may still be weeks away from killing frost, but we’ve already had a couple of light ones here in Alberta.

Last winter I geeked out and did a bunch of reading on frost, thinking some theory might help my practical application this year. I had visions of early planting, and harvesting veggies and displaying flowers well into October. Not much of my vision materialized, as I still live in the real world, and I definitely haven’t reached the caliber of Niki Jabbour, but it’s cool to understand more about how weather works. And spreading sheets over the pumpkins with a flashlight after dark last week was totally worth buying them another couple of weeks’ growth.

Here’s a few things I’ve learned this year that may help you predict, and hopefully outwit, Jack Frost, and buy yourselves a little more time in the garden.

First off, find a weather website you like or buy one of those weather stations from the hardware store. The Weather Network actually has a Lawn and Garden forecast, including frost predictions and watering advice. A little info goes a long way.

Next, be prepared for frost. Have some old sheets or lengths of burlap ready to cover plants, as well as something to weigh them down against the wind. Small straw bales, a cold frame, or cloches will also do the insulating job. Have a spot in mind in the shed or garage to move containers of annuals to when you get a frost warning. Do a little research if you’re not sure which of your plants need frost protection. Bronze, hairy, or compact plants, as well as those closely spaced, will be naturally more protected, but don’t count on most annual flowers, squash, tomatoes, peppers, or corn to stand up to frost without being covered overnight. Carrots, beets, and most members of the cabbage family, as well as many other vegetables, don’t mind frost.

If you want to actually predict a frost, the first thing to do is look up. Clear, calm skies are a sign frost make strike, especially if afternoon temperatures start falling fast. Frost is less likely to occur under a cloudy sky, or when there is fog, as the day’s heat is trapped closer to the earth. This is part of why covering plants protects them–it traps some of the heat from the earth close to your plants.

Then assess the wind. If it’s strong, especially if it’s coming from the northwest, cover things up. Movements of large, cold air masses often bring on killing frost. But very still nights allow the coldest air to settle to the ground, also risking the temperature for your plants to hit zero. A light breeze will keep temperatures higher, unless that wind itself is below freezing.

Higher humidity decreases the risk of frost. This has to do with all the high school chemistry you’ve blocked out regarding warmer air being able to hold more water molecules. (See the next bit on dew point.) I’ve known people to water in annuals to protect them when a light frost threatens, though I’ve never tried it myself. The science backs them up: when the air is dry, evaporation sucks warmth out of the soil, making for chilly plants. By attempting to increase the moisture available, these gardeners “insulate” plants from the cooling effect of evaporation. Same goes for the old standby of covering things–it keeps the moisture close to your plants.

So here’s the real nitty-gritty of how frost actually appears–feel free to skip this paragraph if you’re not into scientific explanations. Basically, the dew point is the temperature at which the moisture vapor in the air will condense back into liquid, based on the given factors, most importantly, humidity. If the air temperature drops to the dew point above freezing, you get wet summer grass and diamond-scattered spiderwebs. If the dew point is below zero, and the temperature drops to it, the water vapor is changed directly into solid form–ice–and you see lovely feathery crystals on the edges of everything. Now, if the dew point is below zero, and the air temperature drops below zero but doesn’t reach the dew point, you won’t technically have frost, but tender plants will be damaged by the freezing temperatures. The other thing that can happen is the water vapor condenses at a dew point above zero, leaving dew, but the temperature continues to fall below zero, forming a coat of ice. So if you know the dew point and the overnight low, you can predict a frost.

If you’re really of a mind to change your relationship with frost, you may want think right down to the bones of your garden, your location and its physical features. Ever noticed that your neighbor can get white tipped lawn when you don’t? Higher altitude increases frost risk because the air is thinner and the average air temperature is lower. But low areas in the garden can be more susceptible to freezing because cold air is heavier than warm and tends to sink. Gentle slopes that expose the garden to the sun are more protected, open spaces plagued by wind are not. Houses, fences, and water bodies can be heat sinks and/or wind breaks that protect from cold air. Allowing places in the garden where wind can move, and hence, cold air escape, will also be protective. And that old saw about starting with the soil if you want better plants? It’s true in this case too: Fertile soil holds more moisture and passes it into the air more efficiently compared with sandy or deficient soil. And we know that humidity is good.

There. Don’t you feel smarter?

 

 

 

The pre-autumn slump

I came home from vacation to find more than a bit of a mess in my garden. Three weeks of heat and a temperamental irrigation system meant that things didn’t get watered consistently and all the annuals are dead or flat-lining. I thought I’d gotten the weeds under control, but they were back, seeding their fool heads off. The peas were overripe, the broccoli bolting, the onions flowering. Sigh.

Half of me wants to start a flurry of work and get things ship-shape again (or finally, depending on your perspective), and the other half of me wants (gasp) winter to show up early to hide all my sins, and just start again next spring. (If the “s” word starts falling in the next 48 hours, I guess you can blame it on me.) I’ve spent the week trying to catch back up. Some things have gotten done, but the list is getting longer instead of shorter thanks to the fall chores starting to arrive.

I thought I’d cheer myself up by planting some trees. A neighbor gave us some seedlings he cleaned out of his windbreak: three maples, two ash, and a random crab apple. I got four in the ground, watered and mulched, and then it started raining. While out there, I also realized that four trees at the very back of our property which we were told were baby Manitoba maples when we put them in 6 years ago, aren’t maples at all. They’re ash trees. I’d taken some one’s word and never looked closely again until now.

I feel like an idiot.

And my garden is a mess.

And it’s raining. Okay, that’s actually kind of good, just not what I was hoping for…

Maybe things aren’t that bad. It’s just days like this that make me think I’m a better writer than I am a gardener. At least, I hope I am.

Wow. I’m sure I’ll get out of this funk when fall sets in properly; it’s this in-between that’s getting to me. Anyone want to join me at the greenhouse tomorrow to look at the pretties? Maybe I’ll choose some fall bloomers to disguise the travesties in my front yard. That should get me through until it’s dry enough to work again.

And please forgive me for even mentioning the season coming next.