Creating a Windowsill Herb Garden That Survives Halifax Winters

One December evening, after work, I was standing in my kitchen looking down at a withered basil plant. It was my third attempt. The stems had turned black, and the soil smelled of mould. In Halifax, the winter sun disappears by four in the afternoon, and the only light that comes through my apartment windows is a pale glow reflected off overcast skies. Trying to grow herbs in these conditions was perhaps a little reckless.

But I couldn't give up on herbs. After spending a day at the pharmacy, I needed time to touch something with my own hands, to smell it, to tear off a few leaves and drop them into a cup of tea. Dried herbs aren't bad, but there's no comparison to the aroma that rises when you pluck fresh mint leaves and steep them in hot water. When my stomach is upset, brewing tea from peppermint I grew myself feels far more satisfying. It might be a placebo. I don't mind.

After three failures, on the fourth winter, I finally kept basil, thyme, and mint alive through to spring. Over two more winters after that, I refined my methods. They're not perfect, but I've at least reached the level of "won't die in winter."

Light is the whole problem

Halifax's winter sunlight is dismal. Between December and February, you're lucky to get one or two clear days a week. A south-facing window would be ideal, but my apartment faces east, so sunlight only comes in briefly in the morning. That's nowhere near enough for basil to survive.

I ended up buying a grow light. At first, not wanting to spend much, I just clipped on a single LED, but even that made a huge difference. Now I use a full-spectrum LED bar mounted on a shelf above the windowsill. I keep it on for about 12 to 14 hours a day. With a timer plug, it turns on at six in the morning and off at eight in the evening, so there's nothing to think about. The grow light and timer together cost about $40.

One thing I learned: distance matters. At first, I mounted the grow light quite high above the plants, and the basil stretched toward the light, its stems growing thin and leggy. Keeping it about 15 to 20 centimetres from the tops of the leaves made a big difference. I stack books under the pots to adjust the height. Right now, two old pharmacy textbooks are serving as pot stands on my windowsill.

Temperature, water, and Halifax's particular dryness

When the radiators kick in during winter, the indoor air gets surprisingly dry. For herbs, this is a double blow. The soil dries out fast, and the leaves turn crispy. Basil is especially sensitive to dryness.

My method is simple. I place a tray lined with gravel under the pot and fill it with a shallow layer of water. Submerging the pot directly would cause root rot, so I set the pot on top of the gravel so the bottom doesn't touch the water. As the water evaporates, it raises the humidity slightly around the pot. It seems like a small thing, but after I started doing this, the browning at the tips of the basil leaves noticeably decreased.

For watering, I press my finger into the surface of the soil and decide from there. When the top centimetre or so is dry, I water. Thyme is sensitive to overwatering, so it's fine to let it dry out a bit more. Mint is the opposite: it likes water, so it's better to keep it slightly moist. Growing all three side by side, I realized they each have different watering schedules. There's an oddly similar instinct to adjusting dosages to match each medication's characteristics when compounding prescriptions. Have any of you noticed your day job creeping into your hobbies like that?

A temperature between 15 and 22 degrees Celsius is ideal. In Halifax's older apartments, there's a dramatic temperature difference between right next to the radiator and right next to the window. If a pot on the windowsill touches the cold glass at night, the root temperature drops sharply. I wedge a small piece of Styrofoam between the pot and the glass. It's not pretty, but it works.

Which herbs to choose

Honestly, basil is the most finicky. To keep it alive in winter, a grow light is essential, and even then it won't grow as lush as it does in summer. But I still can't give it up, because a tea made by steeping a few basil leaves with honey in hot water is the first thing I reach for when my throat feels scratchy.

Thyme is surprisingly tough in winter. As a Mediterranean plant, it tolerates dry conditions well and doesn't fuss much even when light is a little lacking. In my experience, it's the least demanding of the three.

Mint is practically immortal. The problem is that it grows too well. You must plant it in a separate pot from your other herbs. I once planted mint in the same pot as basil, and the mint roots took over the entire container. The basil was crowded out in less than a month. Mint deserves its own small pot.

Soil, pots, and drainage

The biggest mistake I made in my first year was using a pretty ceramic pot with no drainage hole. I also make pottery as a hobby, so it's a bit embarrassing that I fell for a beautiful glaze finish over function. The result was waterlogged roots and mould. Now I use terracotta pots with holes in the bottom, with a saucer underneath. Terracotta is great because you can check the soil's moisture level by sight. If the sides of the pot look wet, there's enough water; when they dry to a light colour, it's time to water.

For potting mix, I use regular potting soil mixed with perlite in a 3:1 ratio. The perlite helps with drainage so the roots can breathe. Good drainage is especially important for thyme.

I hardly fertilize at all during winter. Giving too much fertilizer during a period of slow growth actually backfires. A very diluted liquid fertilizer once a month is more than enough.

Sometimes when a customer at the pharmacy asks about herbal tea, I mention my homegrown herbs and the conversation goes on for a while. One person said they wanted to try growing herbs in winter too, and what I told them then still holds. Don't try to create the perfect environment. Just observe three things: light, water, and temperature. The plant will take care of the rest.

This winter, I'm thinking of adding rosemary. Whether I succeed or fail, I'll write about it here again.