Last year I grew potatoes in buckets. They did better than their siblings in the ground so far as resisting the late blight we got after a horrendous month of rain in June. They also offered the advantage of being really, really easy to harvest, and of being impervious to rodents who would gnaw the tubers underground. The yields were good, but I didn't see the prodigious and strangely elusive yields that are rumored to be possible with exceptional hilling. You can read about last year's harvest here.
The bucket system last year was very simple. I used mostly 5-gallon buckets, along with one smaller kitty litter bucket. All I did was drill several holes in the bottom of each bucket and start the seed potatoes in a few inches of a mixture made from our clay garden soil and compost from our township's yard waste facility. I hilled the plants as they grew and they reached the tops of the buckets in very short order. Then it was just a matter of keeping them sufficiently well watered. This was probably the most challenging thing about growing them in buckets.
Since last spring I've done some research on the growth of potato plants. Here's what I've learned. There are two critical phases of plant growth that affect tuber production. The potato plant sets a certain kind of root that produces tubers early in its growth. Tiny seed tubers are produced at that time. Then the plant concentrates on top growth - the leafy green parts we see above ground. When there is sufficient leaf surface for a good deal of photosynthesis to take place, the plant flowers and then works on storing excess energy in the tubers, which grow rapidly during this phase. At these two phases of growth - the production of the tiny tuber "seeds," and the bulking up of those tubers - a steady water supply is absolutely critical. The kicker is that there's no way for a layman to tell by looking at the top growth when those phases are happening.
So my solution is to try self-watering containers. Basically, I'm using the exact same technique I put in place for my fig trees, writ small. To make these smaller self-watering containers, I tried to collect smaller cans for the reservoir, such as for wet cat food or canned fish, but I came up rather short in that area. My husband came up with a pretty good workaround for that. (See below.)
As usual, I've been running late with getting everything planted this spring. Getting the majority of our potatoes into the ground was a higher priority than the refinement of my container potato experiment. But the potatoes are finally in their buckets. So here are the steps. Click on any of the pictures to enlarge.
Collect your materials: You'll need buckets, a piece of cardboard, a permanent marker, scissors, the sort of cans that catfood or fish are sold in, some hardware cloth, burlap or some other absorbent and cheap material (ratty old towels?), and dirt. You'll need about three cans for each bucket you want to plant. If you're short of cans, have extra hardware cloth on hand to make support rings for the cans you do have. You'll also need something to cut the hardware cloth with, a drill to make holes in the cans, needlenose pliers, and (ideally) a mandrel bit large enough to make a hole to accommodate the end of your garden hose, and a kitchen scale if you wish to keep records. You may or may not want to take the trouble to find food-grade plastic buckets.
Prepare your materials: Drill one hole each in the side and bottom of each metal can. Trace the bottom of the bucket on the piece of cardboard and cut it to make a template. Arrange three cans in the bottom of a bucket and set the template on top of them. Does it rest on top of the cans with a little gap all around? If not, trim it until it does. Use this template to cut out a piece of hardware cloth for every bucket you wish to grow potatoes in. Using the pliers, crimp back the sharp edges of the hardware cloth in a 2"-3" length edge of each piece. Then take the template and trace out circles on your burlap, but leave a wide margin around the template. You want the burlap to be larger than the cardboard by about 2" all around. So just put the template on the cloth to give you an idea. Mark out one circle of cloth for each bucket. Cut the burlap circles out.
Assemble the buckets: Set a few of the cans into the bottom of a bucket. Place the hardware cloth on top of it and mark a spot on the outside of the bucket so show the level of the hardware cloth inside the bucket. This point will become the top of the water reservoir. Take the hardware cloth and cans out of the bucket. Using the mandrel bit and an electric drill, make a large hole with its lower edge just where you made the mark on the outside of the bucket. Replace the cans in the bucket. Take the hardware cloth and note the area where you crimped back the wires. Wrap the hardware cloth in the burlap and set it into the bucket, on top of the cans, with the crimped edges directly facing the hole you just made. Tuck the burlap down all around the hardware cloth, except where the hole is. Lift the burlap to cover the hole at that point. This will prevent the soil from spilling out of the bucket when you fill it.
Plant the potatoes: Put two inches of good soil on top of the burlap. Take your chitted seed potato and remove all but 3 to 4 of the largest sprouts from it. Make sure all the sprouts you leave are pointing more or less in the same direction. If you wish to chart your yield ratios, weigh the seed piece. Record the weight and variety of the potato on the outside of the bucket, using the permanent marker. Place the seed potato on the soil, with the sprouts pointing up, and add more to cover the potato by 2 to 3 inches. Place the bucket where you wish to grow potatoes and fill the reservoir with water. Check the reservoir again after 3-6 hours and top it off if it is low.
Bucket planted with a German Butterball seed potato weighing 3.7 ounces
After planting, keep an eye on both the water reservoir and the plant growth. Check the water reservoir by putting your finger in the hole and top it off with water whenever the level seems low. As the plant grows, add more soil, leaving only 2"-3" of top growth above the soil line until the plant is above the edge of the bucket. When the plant has died back in the fall, harvest is easily accomplished by dumping the bucket into a wheelbarrow and picking out the tubers. You won't have to worry about any gnawing from rodents.
I'm pretty confident these potato buckets can be used any time after the danger of real freeze is past. A short frost won't bother the seed potatoes in these buckets. And if freakishly winter weather is forecast after you've put your potatoes in these buckets, you can always put them in the garage for a few days.
Aside from the new container system, I'm introducing two other variables in this year's potato bucket experiments. I'm trying the Carola variety alongside the German Butterball that I grew last year. A few people have reported success with getting the Carola to set additional clutches of tubers higher along the plant stem than where the seed potato was planted. I didn't see this happen with the German Butterball last year. Also, I will try to be extremely punctual in hilling the plants this year. Some have speculated that potato plants do not set additional tuber-producing roots once the stem hardens off as it grows above the soil line. Since I can only hill to the height of a 5-gallon bucket, minus the height of the water reservoir at the bottom, I should only need to watch carefully for plant growth for a few short weeks. I plan to hill assiduously, leaving only a few inches of top growth visible, until the plants clear the top of the bucket. After that, they'll be left to grow, flower, and bulk up their tubers. I suspect that the potato tower technique, which forces the plant to grow, and grow, and grow, continuously striving to stay ahead of the hilling, is stressful on the plant and gives it less time to set its top growth and settle down to the business of productive photosynthesis.
We'll see how it goes. I'll also be growing some potatoes in the normal way, in the ground. Any of you planning on a special potato growing technique this year? Do tell.