Sweet potatoes are a heat loving summer crop. They are not suited for northern climate nor a short growing season. Here at Northern Homestead we are dealing with both.
But sweet potatoes are tasty and so good for you. We love them baked with some homemade sour cream, yum.
So why not try to grow them? I have to start by confessing that I haven’t been able to get a real harvest, yet. But I also haven’t given up yet either. The picture shows my best harvest so far – looks promising to become more, doesn’t it?
The other day we started talking about sweet potatoes in our local gardening group. I quickly learned that I wasn’t the only one that wants to grow them in our cool climate.
Just a side note, those local gardening groups on facebook are so valuable, if you don’t have one, start one! You will be glad you did. No one knows better how to grow than experienced gardeners in your area.
Back to sweet potatoes.
What Sweet Potato variety to grow
Sweet potatoes are not potatoes at all. Potatoes are from the night shade family, sweet potatoes are from the morning glory family. There are many Sweet potato varieties, but to my knowledge for short growing seasons you can only get one.
Veseys seeds offers Covington, an improved early variety that will mature in short season areas with proper care. It has bright orange flesh with beautiful, deep rose coloured skin. For more varieties check out the Farm Fresh Produce.
My trial was with a store bought organic sweet potato. I have no name for it, since stores do not tell us what variety it is. It could have been a Covington too, since those are very popular.
This year I’m going to try both, the store bought one and the Covington from a local grower.
Where to get a sweet potato slip
Sweet potatoes are grown by slips that look very much like a seedling. Slips are grown from a mature sweet potato. You can order slips from a seed company or grow your own.
The challenge with ordering sweet potato slips from a seed company is that they ship late in the season, here in Canada in June. This is due to the sweet potato slips being extremely cold and frost sensitive, and the fact that they need to grow to a certain size before they can be shipped.
Once arrived in the mail they will often look wilted and should be placed in water to root for 4 to 5 days or be rooted in a soiled mix for 7 to 10 days. Once the plants have begun to root they can be planted outside. If you do the math, June has almost passed by now and there are less than 90 frost free days left.
Growing your own has the advantage that you can be earlier and the slips will not have to go through a shipping shock.
How to grow sweet potato slips
Find an organic sweet potato you like in your local store, or even better ask around if anyone in your area has grown them. You will have to start growing the slips about 3 months before you want to plant them. Late January to early February is a good time.
Why so early? Our growing season is very short. The only way to prolong it is up front. We can start a plant earlier in order for it to still produce something. Planting sweet potatoes out in June is too late.
Wash the sweet potato and place half of it in water, hold it above the water with some toothpicks. It kind of looks cool that way, too.
Now place the potato in a sunny window and/or under a grow light and let it grow slips till they are at least 6 inches long.
Than you take those slips off of the potato and place them in their own jar of water till they grow nice and healthy roots.
How to plant sweet potatoes
Now plant the seedling into a pot, grow bag, or directly in the ground. Note that sweet potatoes are heat loving plants. A container will warm up the soil better. If planted in the ground, plant them through black plastic mulch to warm the soil. You need a sunny, sheltered location. In our cool summers we plant them in a greenhouse.
Sweet potatoes also like a loose, well drained soil. Our northern heavy soil is not the best choice. You can use a good potting soil (add some more compost to it for nutrients) or mix your own soil the Square Foot Garden way: 1/3 compost, 1/3 vermiculite, 1/3 peat moss.
If grown in a container, give the plant enough room to grow. My first trial pot was too small. Grow bags are always better for container growing.
Give the sweet potato plant protection
Sweet potatoes do not tolerate any frost. They love the heat of summer. In our area there is not much we can offer a plant in this regard. The heat loving plant will need help.
If you have a greenhouse, you can grow the sweet potatoes in there. My first try was enjoying the warmth next to tomatoes and peppers.
If you don’t have a greenhouse you can build a mini greenhouse or hoops for the plants. This is very important in the spring while plants are still young. Remember, I like to start early to give the plants more growing time. But in early spring there is still real danger of frost.
Give the plants as much protection as you can give outdoors. I like the Plant Protection Blanket; it is light weight and can be left on for days, as the weather permits. You can cover a whole bed with it, or wrap individual plants.
Or build a wind barrier out of recycled windows. Anything that will give the plants more heat works.
How to harvest sweet potatoes
Sweet potatoes are ready to harvest when the leaves start to turn yellow. However, in our area it is more like once the weather gets cold the plants will be done because they should be harvested before the soil will get cold.
If you grew them in a pot, just simply empty out the pot and gather all the sweet potatoes. If grown in soil, gently dig them like you would potatoes.
Sweet potatoes might not be ready to be eaten just yet. After harvest let them rest in a dry place at room temperature for 4 to 8 weeks for the sugars to form in the potatoes!
Have you grown sweet potatoes in cold climate successfully? Please share your know-how with us. If you haven’t, maybe you want to start the adventure today.
I will update this post as we grow, cheers for a good harvest!
Grow Bags make great containers for growing potatoes. Make sure to choose a bigger size.