If you’re wondering how much cold your lemon trees can talk over the winter, click here to see what I say in my book Grow Lemons Where You Think You Can’t.
Lemon trees can tolerate more cold than many people realize, meaning there are more options for keeping them through the winter. They don’t need a greenhouse or bright south-facing window!
In this Biggs-on-Figs segment from The Garage Gardeners Show, I chat with Tom Ashely and Linda Crap from Dancing Bear Farm in Massachusetts to find out about what they do and how they got into growing figs.
IT’S MID NOVEMBER and my fig trees here in Toronto have dropped their leaves and gone dormant. I moved my potted fig fig trees into my garage (I keep the temperature in the garage near freezing over the winter.)
But like many fig growers in areas with cold winters, I still grow figs in the ground and give them extra winter protection. A common way to give that protection is to insulate the tree by burying it.
At this time of year, I use a spade to chop away the roots on one side of the fig plant—and then lay it flat against the ground.
Some people avoid the burying method of overwintering figs, worried about the work of digging. Once, after I gave a talk about figs, an audience member came up to me to confide that he had tried burying his fig tree, but it was too much work to dig down six feet! I reassured him that it’s not necessary to dig his fig plant a grave—that at the most he needed a shallow trench. Then I explained that around here, the fig plants are usually fine if you lay them flat against the surface of the soil and put a thick mulch on top. You don’t even need to dig a trench!
You will see in the above photos one of my fig trees before and after. Once the roots on one side are loosened and I’ve tipped over the plant, I put a board and concrete block over the top to hold it in place. Soon, I’ll put a thick layer of straw or leaves over the top to insulate it. And when it snows, I’ll heap on some snow too.
But I don’t rush the mulching…mice love to eat fig bark, and I want them to find a home elsewhere before I mulch my figs.
If you’re thinking about overwintering your fig, here are a few other ideas for you:
My friend Bernie in Edmonton, Alberta, recently sent me this photo. There’s a fig tree in there, even though you can’t see it!
The fig tree is buried in a trench alongside the foundation of his house. He covers the buried fig tree with a few bags of leaves—like a blanket to keep it even warmer. Once snow arrives, he covers it with snow for added insulation.
Bernie also has potted fig trees that he stores in the safety of his garage for the winter—a more common fig overwintering technique in his garden zone. But he enjoys experimenting with other ways to overwinter figs. (I can understand this because whenever I run out of room for overwinter figs, I try a new method, allowing me to keep even more plants!)
Why bury the fig tree beside the foundation of the house? The soil close to the foundation stays a bit warmer.
Bernie uses a max-min thermometer to track temperatures. Last winter, the temperature around his buried fig tree dropped to 2°C (36°F), while outside, the air temperature dropped as low as -36°C (-33°F).
On a recent trip to Vancouver Island, B.C., I stopped in to see Bob Duncan at Fruit Trees and More nursery and demonstration orchard. Bob uses his microclimate in Sidney (near Victoria) to grow fruit that you’d normally expect in Mediterranean climates.
Bob has given me many pointers over the years about growing lemons and olives—and about figs in the Pacific Northwest. More on the olives and lemons in a future blog, but I want to share some fig tidbits here today.
Added Heat for Main-Crop Figs
I’ve written before about how Bob uses a greenhouse with no walls to ripen main-crop (fall) figs. He has mild winters, but not enough summer heat to ripen many main crop figs. The greenhouse is his way of capturing summer heat for his fig plants. They don’t need winter protection where he is.
Bob fed me main-crop figs as we toured his greenhouse in September. So for would-be fig growers in the Pacific Northwest, remember: supplemental summer heat might be the ticket for a fall main-crop harvest.
Breba Figs in the Pacific Northwest
Bob is trialling dozens of varieties with heavy breba (summer) production. I’ve sent him a few of my favourite varieties for breba figs over the years.
I asked Bob to suggest one of his favourite varieties to get a heavy breba (summer) crop. He’s a fan of Grantham’s Royal (a variety I’ve never grown). He says it has a significant breba production. This variety is a “San Pedro” type fig, meaning it doesn’t ripen another crop afterwards (just like the well-known variety Desert King.)
Bob describes Grantham’s Royal as very large and tasty. “It’s one of the largest figs out there,” he says.
Check out the pruning system that Bob is using for some of his greenhouse-grown figs. The main stems are running parallel to the ground with verticals coming off of them.
Fig pruning system: The main stems are running parallel to the ground with verticals coming off of them.
A water-stressed fig tree does something that makes gardeners weep: It drops unripe fruit.
This year I'm growing more figs in large pots with sub-irrigation. It’s a great way to minimize water stress.
I like the sub-irrigation system for places where I can't sink potted figs into the ground for the summer. (When potted figs are sunken into the ground, even just a couple of inches, the fig plant sends roots into the surrounding soil for the summer.)
But my large pots with sub-irrigation are for my driveway...so no rooting out the bottom into the ground for these plants!
Sub-irrigation is a fancy way of saying that you’re creating a reservoir at the bottom of the pot. There is a fill tube that extends upwards so that you can fill up the reservoir from the top. The soil mix acts like a wick and the water moves upwards. You just need some soil that dips down into the edge of the reservoir.
- If the pot has no holes, drill an overflow hole in the side, at the height of the top of the reservoir. This overflow hole prevents your soil from getting waterlogged if you overwater or if there is a lot of rain.
- You can install this sort of system into a container with holes by using a waterproof liner at the bottom.
I’ve often used contractor-grade plastic bags or vapour barrier. Use anything that will hold water within the pot.
The reservoir is the soil-free space at the bottom of the pot where you store water. You need something to hold up your soil mix. You can use weeping tile, inverted flower pots, old juice jugs…just go through the recycle bin and use your imagination.
I find the plastic tubing used for draining dishwashers (look in the plumbing section at the hardware store) is a nice diameter for filling with a hose. You can also use old downspouts, plastic bottles…again, use your imagination.
I like to put some burlap or landscape fabric over the top of the reservoir area to prevent soil from migrating into the reservoir too quickly.
Not Just Figs
I also use sub-irrigation planters on my garage roof to grow vegetables. The planters drastically reduce the frequency of watering, and the plants grow better because they don’t have water stress. Click here to read an article about my rooftop garden.
I recently heard from a fellow fig grower who grows figs on a condo balcony in Toronto...a small condo balcony where winters are cold!
I was so impressed with his creative approach to overwintering figs that I asked if I could share it on my blog. Here it is below, in his words.
I give my thanks to this fig pig (who prefers to remain unnamed) for sharing his experience!
Re: Overwinter Figs Where You Think You Can't: Fig Overwintering for Condos/Apartments
I read the excerpt from your book Grow Figs Where You Think You Can't about overwintering figs, and I applied the basic principles for a condo/apartment situation. I grow figs on my condo balcony in Toronto but have no yard (so no ability to earth-insulate), and no unheated garage or cold, dark room either.
My first year I had only 1 fig tree (about 2' tall). I took a rectangular wood planter box (approx. 3' x 1' internal) and lined it with Styrofoam (and cut out a Styrofoam lid too) to serve as an insulated container. I placed my dormant fig inside.
Since I planned to store it outside on my balcony over winter, I considered various heat source options (e.g. seedling heat mat, light bulb, coffee warmer, etc.). I ended up buying a small 7.5 watt flat oval fish bowl heater (meant to go under aquarium gravel), which I placed into a mason jar full of water that I put inside the insulated wood planter.
The aquarium heater is my version of a DIY water radiator. It has the added benefit of the water jar acting as a thermal mass for heat energy storage and temperature regulation. That is, the water is slow to warm and slow to cool, so temperature changes are gradual and moderated. The other advantages of fish tank heaters are that they are 100% waterproof (so they're safe for wet environments) and they're inexpensive too. A seedling mat was my initial choice but they were far more expensive, plus they lack the inherent thermal mass storage and regulation properties of a water radiator.
The flat plasticized fish bowl heater I used the first year provides continuous heat (no thermostat) and it basically kept the water above freezing and about +5°C to +10°C above the ambient air temperature. Only on the coldest of Toronto nights (e.g. those -20°C nights) did it get a bit too cold, and I needed to wrap the whole container in extra blankets to add insulation.
The next year I bought 3 more figs and needed a larger container so I bought the largest picnic cooler I could find, a marine cooler intended for boaters. I also upgraded to a higher wattage glass fish tank heater with a built-in thermostat. I supplemented it with a thermostat controlled AC plug switch, a ThermoCube TC-3, which turns on AC power to the heater around 2°C ambient air temperature and turns it off around 7°C.
I managed to fit all 4 figs in the large cooler and placed the fish tank heater in a large glass jar filled with water, the power cord running out the top. I taped shut the glass jar top to prevent water splashing out when jostled. I set the fish tank heater thermostat to the lowest level but when paired with the ThermoCube TC-3, the ThermoCube on\off temperatures are the primary thermostat.
Because I needed to lay my figs flat on their side, to prevent dirt from falling out I wrapped the figs in scraps of old cotton bed sheets. Initially I tried plastic but I was concerned about the lack of air flow and felt it trapped too much moisture.
For peace of mind, I also bought an electronic wireless thermometer (ThermoPro, $20) which includes a hygrometer to measure humidity. The sensor component was placed inside the fig cooler and the display screen kept indoors for easy monitoring. That kept me from constantly worrying and wondering what was happening with my figs.
The first year's fish bowl heater was 7.5w and just $13 (Hydor 7.5w Slim Heater for Mini-Aquariums and Bowls up to 5 gal). The second fish tank heater was 200w and just $20 (Pawfly HT-2200 Submersible Aquarium Heater 200W with Thermometer and Suction Cup, 50 gallon).
In my experience, the 7.5w heater was slightly undersized for my DIY insulated wood planter (but it would depend on how insulated the container is and the 200w is certainly overkill even for the larger cooler since the cooler is well insulated. I would suggest anything above 25w would probably work, depending on water jar and container size, and on insulation level.
Having more power is fine as long as you have a thermostat-controlled AC switch such as the ThermoCube to prevent over warming. Most fish tank heaters are intended to maintain water temperature above normal room temperature, and the thermostat minimum on the 200w heater was 16°C. Even with the 7.5w heater and without the ThermoCube, I found I was unplugging it manually on days when the ambient outdoor air temperature was above freezing, and it stayed mostly unplugged beginning early spring.
Bottom line: using a ThermoCube removes the guesswork and the risk of over warming.
Also, since picnic coolers are quite well sealed when the lid is closed, I would recommend leaving the lid ajar to prevent excessive humidity build up and to provide more air flow. Since the fish tank heater is submerged in water, that might also provide an additional source of humidity depending on how well sealed the water container is.
I would recommend only a very light watering before placing the dormant figs inside the cooler as the humidity can remain high in such an enclosed space. In my case, I watered my 4 figs thoroughly before they went into the cooler and they were still moist months later when I took them out in the spring.
Anyway, that's my fig overwintering technique for condo living. I hope this helps others in similar circumstances. It's very satisfying to be able to grow (and overwinter) figs where I thought I couldn't, on a balcony in an urban northern climate. Thanks for the inspiration!
- Insulated container (e.g. picnic cooler) large enough to fit your figs
- Fish tank/aquarium heater and water jar/jug
- Thermostat controlled AC plug (e.g. ThermoCube)
- Wireless electronic thermometer with hygrometer (optional)
Straw for Kids and Figs
I USE LOTS OF STRAW in the garden. Last spring we got 30 bales. When I say we, I mean the kids and me. For the first while, the bales are all for play: giant biodegradable building blocks!
Over the summer, some of the bales break as the twine comes off. I use the loose straw for mulching.
In October, I lay full bales over top of fig plants that I'm growing as "step-over" figs. These plants have low, horizontal main stems.
I cut all of the braches from the main stem in the fall, making it easy to lay straw bales over the top.
With the step-over system, I select varieties that produce a good crop of "main crop" figs. These are the figs that grow on branches from the current season. New shoots can produce figs in one season.
The Challenge in my Garden
So far so good, right? Sort of. The concept is sound—and the straw does a great job of protecting my fig plants.
But...this corner of my garden is low and the soil is slow to warm up in the spring. The result is that my step-over fig plants don't start growing early enough to ripen many figs.
Lesson learned. I've started step-over fig plants in a warmer spot close to my patio.
And the solution for the step-over figs in these photos? Growing figs in cold climates often requires some sort of season-extending technique... And I think that the solution for me might be to install a low hoop-house over top of these figs in the spring. It will warm up the soil and get the plants out of dormancy sooner.
The Biggs on Figs class is back!
Yes, you can grow figs in southern Ontario! Join me to learn about growing and overwintering fig trees in cold climates.
- simple advice about growing figs in a home garden
- first-hand tips on propagating your own fig trees
- of course, lot of pointers on how to keep your fig tree alive over the winter
MOST IMPORTANTLY... see how other gardeners in Southern Ontario overwinter fig plants. Overwintering figs takes a bit of creativity...and this class will get your creative juices flowing!
Toronto Botanical Garden, Wednesday September 13, 2017. Click here for more details or to register.
Around here, we’re only a couple of months away from that first fall frost that puts an end to any hope of ripening more figs.For someone like me, with no background in energy, the comment sounded profound; yet so simple.
The alternative energy expert (whom I interviewed about home energy generation) told me not to forget “thermal mass,” which, he felt, is as important as generating energy. In his projects, he combined solar and geothermal technologies with the idea of thermal mass.
What he meant by thermal mass was using building materials that capture and then slowly release heat, materials such as tile and concrete. It was very logical, of course, but I’d never thought about it before.
We’re in the middle of a heat wave here in the Toronto area. Yet already, the nights are becoming cooler. As temperature swings between day and night become greater, using thermal mass in the garden is a technical-sounding, yet simple way to given fig plants more heat. Remember: More heat for our fig plants means more ripe figs before the fall frost arrives!
If you already have your fig near a paved driveway or brick wall, then it’s benefitting from thermal mass. At night, the driveway or brick slowly radiates heat that has been stored during the day, keeping the air temperature around your figs a bit warmer.
I was reminded of this a couple of weeks ago when I visited my friend Andrea, who recently planted a fig hedge (which she intends to overwinter with an insulated A-frame). As I stepped—barefoot—onto her patio, the dark stone singed my feet. It was scorching hot. When it rained a short while later, the stone dried within minutes because it was so darn hot!
Andrea’s figs have a really great “micro-climate.” They’re surrounded by that heat-capturing and heat-radiating stone. At night, those figs bathe in radiated heat. All thanks to thermal mass.
My fig hedge is looking nice, with the neighbouring peonies adding splashes of pink.
Over the winter, I lay the potted figs in the trench and cover with mulch. The trench becomes my fig hedge over the summer. In the spring, I put the potted figs in an upright position in the trench, and then mulch so that the ugly black pots are out of sight.
Join me this Sunday, April 24 at Plant World in Toronto as I talk about growing figs in cold climates. I'll share the story of my own journey into growing delicious, sun-ripened figs here in Toronto.
2:00 pm - 3:00 pm