Growing Potatoes in Containers
March 17, 2017
Crates, tubs, bags, barrels, wire towers, or specially designed potato planters… What’s the best way for growing potatoes in containers? A question I didn’t know I had until earlier today, but certainly one any urban gardener or container gardener should want the answer to. Because you grow flowers for fun, but veggies are all about providing yourself with the most food possible.
It started with this video of how to make a nifty little potato growing container.
Ingenious idea, right? A super simple, inexpensive approach to growing potatoes in containers for limited space. It looks a lot like a DIY hack for a commercial potato pot currently for sale on both sides of the Atlantic that retails for $12-$19 – depending on the merchant and country. The ready-to-use potato planter is equivalent to a 5-gallon (19L) nursery pot, and the ones used in the video aren’t any larger. Furthermore, the hack costs as much as, perhaps more than, the ready-to-use version, unless you’ve got two identical used pots in the garage already.
Don’t get me wrong. This is definitely a cool way to be able to harvest some new potatoes for dinner without disturbing the rest of your crop. And if you’ve got the space in your grow room, tucking a 12″ wide pot in will allow you to grow potatoes year around. It will take some serious light power, but it’s doable. However, in a planter this small, the potatoes will always be small. Especially if you plant 4 seed potatoes with 2 or more chits (sprouting eyes). Because crowded potatoes don’t get real exuberant. Each chit should have a foot of row space in the garden plot. Yes, you can cram them closer together, but performance will change along with their loss of air flow and root space too.
So, how big of a container do you need to get baking-size tubers? Let’s look at the difference in harvest results when using a bigger pot as a compact potato planter.
In my hunt for visual evidence and better methods, I came across “UK Here We Grow”. This allotment gardener’s 30-liter (16″x14″) pot set up for growing potatoes in containers offers a much better harvest. The closest in US nursery pot sizing is a #15 squat (17.25″x15″) with a volume capacity of 13 gallons. Note that Tony’s not using a standard potting mix out a bag. In fact, no peat moss or coir either. His potting soil is basically 2 types of compost enriched with organic nutrients.
It’s not surprising his resulting tuber size is vastly improved with a bigger growing space. Not to mention his potting media is a far sight better than peat-based commercial blends. And he’s also used only 2-3 chits in planting TWO seed potatoes in containers. When it comes to gardening, more input doesn’t always give you a greater yield. In Tony’s case, just one pot in his growing potatoes in containers crop last summer yielded 3.4 kilograms (7.57 pounds). Not many wee spuds here.
Next, I investigated Dan’s results over at the Allotment Diary, also in the UK, and one of those Giant Veg competitors. He’s using the same size pots as Tony, and both of them chose Sarpo Mira as the examples in their videos. In the 2014 video below, his growing potatoes in containers method enlisted multipurpose compost as the potting medium. The only other plant nutrients added were 2 oz. of Blood, Fish & Bone fertilizer with 1 oz. of Potato Magic (12-11-18) mixed well into half the pot full of compost.
With a whopping 12 pounds plus harvested out of the same size container with the same kind of potato – Dan’s got the best spud harvest yet. But he outdid this last year with another pot of Sarpo Mira yielding 14 pounds. How did he top out the harvest weight? Used nothing but compost and Spuds Galore fertilizer. Check out the size of those tubers!
Why did he switch? I’m not sure, but I couldn’t find Potato Magic fertilizer in a Google search either. Perhaps it’s no longer made. But the analysis isn’t much different than the Spuds Galore brand with 15-09-20 plus 9.5% sulfur (SO3) and 1.8% magnesium (MgO)… That is if I’ve located the right stuff. All I find in search results is an Elixir product labeled Pro Grower Blended Base Fertilizer, which is suggested for many crops, including potatoes. It’s not organic by all appearances but definitely, maximizes your yield.
Last but not least, does a much larger container give you a bigger harvest? That all depends on the dimensions I think. You’d want to go wider rather than lots deeper judging by the results these backyard gardeners in the US got with their 35-gallon barrel used for growing potatoes in containers.
Lots of wasted space and growth media. But wait – uncomposted sawdust is not good potting material. Sawdust, bark, and wood chips are nitrogen hogs. This potato barrel crop had 75% sawdust and 25% sand around the roots. Where’s the compost? Yes, they used fertilizer every week, but the Mittleider Method relies on only 16 nutrients. The growing medium serving no other purpose to your plants beyond covering the roots. It might as well be hydroponic expanded clay or rockwool – at least they don’t steal the nitrogen poured over the top every week.
Naturally, the liquid chemical fertilizers and the totally inert potting mix here have a lot to do with such low yield from all those cubic inches of growing space. She’s not growing hydroponically. A 20-pound yield from a 35-gallon barrel isn’t exciting, but definitely better than some people’s barrel harvests. But it pales when compared to getting 14 pounds in a 13-gallon pot! Plants need a lot more than 16 nutrients and do better without aggressive nutrient competition. Yes, dead wood is aggressive in its use of nitrogen resources. Which is why one should never use wood mulch around annual flowers. It stunts them by hogging the food. And your veggies are mostly annual plant crops.
She would have been miles ahead by cutting the barrel in half to make two deep pots filled with compost and using the right analysis fertilizer at planting time. That would have given her the ability to grow potatoes in containers about 19 inches wide by 15 inches deep. And with just 4 seed potatoes planted. Following Dan’s latest method at the Allotment Diary with nothing but compost, and a comparable fertilizer should result in about 30 pounds of potatoes in the same amount of growing space.
By the way, don’t expect a tower or barrel potato crop to fill the growing area from top to bottom with tubers. It’s possible only if the spud variety you select develops tubers along the entire root. Many potatoes grown in the US today are bred to only develop tubers toward the bottom of the roots. That protects farmers from loss. High tubes too close to the surface turn green, which isn’t good. What this means is that you’ll only have potatoes in the bottom of the deep barrel or tower setup. What a waste of time and materials.
One other thing to note is that Spuds Galore also contains Trace Elements. Curiously, this isn’t stated on the label, but it is on their website. Exactly what they are and how much remains a mystery. However, according to Elixir’s website, the secret to getting more tubers is the inclusion of Sulphate of Potash (K2SO4).
So, how do you get the most out of growing potatoes in containers?
- Be reasonable about the pot size. Small is grand. As long as you want small potatoes in small quantities.
- Never plant more than 2 chits per seed potato.
- Don’t assume you can get what compost has to offer your plants on a store shelf.
- Use some common sense. You can’t get big potatoes if you cram too many sprouts into a container.
- Make sure you’ve got good drainage. And good air flow to roots.
- Don’t let the soil get too dry (causes cracking). Or stay too wet (causes rot).
- Sawdust is great for animal bedding and compost piles, but not potting media.
- And the feeding need not be constant if you use the right stuff to begin with.
That’s growing smarter, not harder while getting the most food per square foot of available space.
Featured image courtesy of Delicious Travels.
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