Potatoes are one of the most influential crops I grow in my garden. They have shaped the course of history and make a good side to quite a few of our favorite dishes at home.
In small space gardens I find growing them in bags has helped me continue to enjoy them without having to dedicate a huge area to them while being able to move them if need be. Grow bags can allow you to grow potatoes of a number of other plants even if you have a space like a patio or balcony.
It is relatively easy to grow potatoes in bags. I have been using these re-usable bags for the last few years. You can also use re-usable shopping bags however they tend to deteriorate a little quicker.
Potatoes do require significant amounts of nutrients to produce well. In order to grow my potatoes using no products or fertilizers I use a soil mixture that is nearly all compost.
The bottom I start with a layer of nearly completed compost made with free and local resources I have generated at my house.
As the compost finishes breaking down it will release nutrients just as the plants roots reach it. Usually in my garden the compost comes with a large number of earth worms. Earth worms help release nutrients in the soil while inoculating the soil with beneficial microbes and plant growth hormone.
The relatively small soil volume in these bags and higher average soil temperatures cause by the green colour will result in you needing to water more often. The remainder of the bag I fill with a mixture of soilless potting mix and completed compost. Both compost and soilless potting mix have high humus content and hold water well. To top things off Ill usually mulch the top to prevent further water loss and continue to add more nutrients.
Potatoes can be started from seed similarly to how you plant your tomatoes or more commonly from what’s called a seed potato. A seed potato is simply a potato that has eyes growing out of it. These are the beginnings of a new plant.
I filled my potato bags ¾ full and plant my seed potato in late April 2-3 weeks prior to the last frost. Potatoes are not overly frost tolerant however the extra time allows them to begin to get established below the soil before sending out the first set of leaves around the last frost date. If they emerge before the extra bag space above lets me easily cover them to prevent damage.
Over the next few weeks the soil will settle as the plant gets taller. Once the plant is 30cm or 12 inches tall I will mound them. This process helps protect the tubers from exposure to the sun which causes the development of pigment and oxalic acid in the tuber, ruining the taste and potentially making them irritating to eat.
It usually only takes a few weeks for this to happen so I usually plant in another seed potato.
There are two varieties of potato just like tomatoes. Determinant will grow and produce one crop all at once. Indeterminate will continue to produce roots and tubers as long as you continue to mount the soil around the stock.
I select determinant varieties growing this far north as generally they produce faster helping me to harvest a crop in my short season. The second seed potato allows me to produce tubers further up in the soil column mimicking what would happen with an indeterminate potato essentially doubling the production from the same soil.
I usually wait until the plant above the surface begins to look stressed in early August. It is now time to harvest.
Harvesting the potatoes from a bag is much simpler than digging up a garden bed. You can use your hands to dig for the crops or simply pour the soil out and collect the potatoes.
As you can see per bag with two plants you can get quite the haul.
The soil I will either put in a tote and re-use next year with fresh compost or use to top dress garden beds to bring the soil levels up.
This year I also grew a grafted tomato/potato plant in a bag on the deck. Above the ground it is a tomato plant and below potato. Once the tomatoes are done producing it will be interesting to see what kind of harvest of potatoes come from the plant.
Of interesting note I found it very difficult to keep up with the watering on the grafted plant when compared to the other tomatoes and potatoes I have growing in similar bags.
If it all works out a grafted plant may be an effective way to continue to increase the production of my garden!