Up here in central-western Alberta, summer is often just a suggestion and more accurately called “mud and construction season”, and spring and fall are unofficially known as “late winter” and “early winter.” To add insult to injury, our soil consists of an inch or so of decent top soil and then concrete. Well, not literal concrete, but it’s such compacted clay that the only things that can penetrate it, un-amended, are weeds (because, of course). And sticky… you will walk right out of your boots trying to walk through mud. Take a step and find your socked foot in mug with your boot a step behind *grumble* So, it is usually a bit more work that digging a hole in your “never been used as a garden” back yard and tossing in some seeds. Usually.
The Basics: an overview of how to grow potatoes
Buy seed. Plant in healthy, well draining soil, shortly before last frost, or before May long weekend around here.
Keep watered, about weekly. Watch for diseases and pests. Occasionally “hill” soil to cover the bottom few rows of leaves to encourage more growth.
Skip every other watering when the leaves start to die back.
Generally harvest about 2 weeks after the leaves have completely died.
In depth look at growing potatoes from seed buying to storage
Zone 3 seed potato choices
Your first decision is choosing what potatoes you want to grow. There’s a list of available potato varieties in Canada, but for best results as a new grower, buy from a local greenhouse or garden center (truly locally owned, not a chain). They take into account local growing conditions when they bring in seeds to resell. You can buy seed potatoes, or you can try using potatoes from the grocery store that have started to grow; cut them into 2 or 3 pieces, keeping 2 or 3 healthy roots per piece. Regular potatoes are often treated to resist growth, but if you have a few potatoes in the pantry that have sprouted really well, stick them in the ground. Organic potatoes don’t get treated and may sprout better.
In Canada, most of the varieties we can get are called “intermediate” varieties (not “determinate” – early season – or “indeterminate” – later season – but they have characteristics of both), so they are classified by their maturity dates instead of in/determinate variety:
Very early: 65 to 70 days
Early: 70 to 90 days
Mid-season: 90 to 110 days
Late: 110 to 130 days
Very late: 130 days and more
I’ve successfully grown from seed potatoes, and from potatoes that I let start growing. It’s most important to just get the highest quality of what you are able to obtain in the varieties you want. Good quality seed potatoes first, then organic regular potatoes, or regular potatoes, if no seed potatoes are available. Skip over any that don’t look healthy: wilted, wrinkled, moldy, and/or bad smelling. “You can’t make a silk purse from a sow’s ear.” Pay attention to each potato’s growing season and plant accordingly. If you shop early enough, you’ll be able to pick from reds, yellows, russets, ect.
Potato tops do grow flowers and seeds, but potato genetics are weird and you won’t end up with the potatoes that grew under ground.
Planting potatoes in zone 3 clay soil
The better your soil, the better your potatoes. It’s important that you have well draining, healthy soil, also known as loamy soil. Potatoes also like a little more acidic soil than most other plants, but will grow in more alkaline soils. If the soil in your ground isn’t optimal, grow in containers while you work on amending your ground soil for next year.
To improve your garden soil, mix in compost, top soil, well aged manure, peat moss, straw, old hay, really any organic material, just be cautious about spreading noxious weeds like thistle. You can also do a layered approach (often called lasagna gardening, or no till gardening) in which you put down unprinted, clean cardboard (remove all tape and stickers) then layer topsoil, and all the organic material mentioned above. The cardboard helps kill any weeds and provides a longer term source of organic material as it naturally composts.
Rotate what you grow
Never plant potatoes where potatoes, tomatoes, peppers, or eggplant were grown for at least the past 2 years, optimally 4 years. Crop rotation is vital for a healthy garden and is one of the major problems in commercial agriculture: not enough crop rotation leads to diseases and poor nutrients.
Does the water you use matter to your potatoes?
In general, even if we have nasty well water than needs major filtration for human use, plants don’t care. If you have any doubts about the safety of your water, have it tested. City water should have chorine filtered out.
Caring for potato plants while they grow
Potatoes aren’t a super picky plant, and they’re relatively easy to grow once they’re in good soil. However, bugs and disease can strike any garden, so there’s some things you can do to naturally tip the scales in your favour.
Beneficial nematodes and lady bugs can be bought and released into your garden to help get rid of the bugs that threaten all your plants, without harmful chemicals. Diatomaceous earth is a powder made from algae fossils. It’s safe for all humans, livestock, and pets, but it’s very effective in killing garden pests, and has many personal uses as well as farm and commercial applications. Food grade is suitable for feeding to animals and people, for example, as a dewormer.
When it’s time to water – about once a week – water early in the day, low to the ground, to avoid getting the leaves wet and prevent blight. Water less often when the leaves start to yellow, so the potato’s skins can thicken before harvest.
Visually inspect the leaves often and physically remove any aphids or other pests immediately. Remove diseased plants quickly and carefully to avoid spreading (don’t shake the diseased plant over healthy ones, for example).
The timing and technique to harvesting potatoes
Wait to harvest until the leaves and vines have all died back from frost or age, plus 2 weeks, and carefully loosen the soil and dig out all the potatoes.
To loosen the soil: Using a hay fork, insert it into the ground about a foot back from where you’d guess the edge of the potatoes grew to. This is not an exact science, so use the first plant as your tester and adjust future jabs. You don’t want to try to use it like you would a shovel. Push in, tilt the handle slowly back until it’s almost parallel to the ground, let it go and get down on your hands and knees and reach into the dirt to get all the potatoes you can. The hay fork is only to loosen things up under there, so your hands can gently get them out.
Long term potato storage after harvest
Once you’ve harvested all your potatoes, big and small, set aside the tiny ones for next year’s seed potatoes. Eat damaged, thin skinned, and soft potatoes quickly, store the rest in a humid 45f/7c for the season. A secondary refrigerator, set warmer than normal, is generally the best option for long term potato storage in most of Canada and the Northern US. It’s just too cold and dry anywhere outside and too warm inside, for most of the post-harvest season. Regularly keep an eye on your storage and pull out and use any that aren’t storing well.
Are Green Potatoes Safe to Eat?
You can eat the non-green parts of potatoes – the green is a sign they were exposed to too much sunlight and produced a toxin call Solanine (that is a pesticide that protects the plant from pests) – just cut the green off and cook the rest.
US States and their universities have a fantastic system called the Cooperative Extension System. They are an absolute treasure trove of information about a whole lot of rural life topics. On a related note, I’ve also found a load of fantastic information from the University of Alberta website regarding chickens and lots more.