A few years ago I’d heard that potatoes could be grown in tubs, in unheated poly tunnels and greenhouses during winter, so I thought I’d have a go.
I came across some chitted ‘Home Guard’ seed potatoes in a home supplies store in February, the heated store triggering the chitting, and consequently triggering my experiment. I planted one seed potato in a tub in the poly tunnel, and three more outside.
The early outdoor plants were always going to be a risk and got hammered by a single, hard, late frost, and though they came back later, they lost all their advantage over the remaining seed potatoes which were planted at the correct time.
However the indoor tub grown potato continued unharmed and developed into a lovely lush plant and provided potatoes many weeks before the outdoor ones.
This small success encouraged me to plant more in containers next year which would give me an early crop and frees up outdoor ground for other things. I grow winter spuds every year now, harvesting the first small crops in May and continuing right up until the outdoor ones have flowered.
So if you have a greenhouse or poly tunnel a good way to make use of the winter space is to plant spuds in containers in January or February. The spuds become ready for harvest in May-Jun. You harvest them making space for cucumbers, squash, tomatoes, etc.
Very early harvests in May give a small but wonderful early crop. Leave them a month and they will begin to fill the pot. I use winter planted, pot grown spuds to give me fresh potatoes until my ground grown ones are ready, and I use spare seed potatoes. With free compost and surplus seed spuds everything is therefore free, so I don’t care if the early yields are low, I only care that I have fresh, home grown spuds. By harvesting from containers in May, June, and July , and then later from the ground, I can have fresh spuds from the ground for about 7-8 months of the year.
Fancy a go?
You need four things:
1 – Compost
Bought or home made.
I plant mine in compost generated on the allotment in a composting bed (click here to read article on composting beds), and after the potato harvest the compost then becomes mulch elsewhere in the garden, so nothing is wasted.
2 – Containers
Large plant pots are ideal but growing bags, and leaky buckets will do just as well.
I find a solid container is better than a bag because you may need to move it around as your greenhouse or poly tunnel becomes planted up, or even move it outside if the weather comes good. A rigid tub causes less disruption to the roots as it flexes much less than a bag. If your tub will never move then it can be as big and heavy as you like. Large plant pots will take one seed potato but larger containers will take 2 or 3.
3 – Chitted potato
These can be obtained, ready chitted in hot ironmongery type departments stores as early as February, where the heat triggers them into chitting. Otherwise you need to save some of last years potatoes and chit them yourself.
I have planted un-chitted spuds and they mainly come up just as well but there is a danger one or two might not.
Bring a few spuds in from the cold at Christmas and they will chit in January
4 – Greenhouse or poly tunnel
Either will do and they never get too hot in the early art of the year.
I fill a container with two thirds home made compost, lay the chiited spuds on top, then cover with bought compost (to keep the weed seedlings from popping up from my home made stuff). Top up as the plants emerge.
Put a single spud in a large plant pot or other similar container.
The seed potatoes sprout in mid March, before other people have planted their spuds outside
In the early part of year, when heavy frosts might penetrate the poly tunnel, I put a piece of glass over the containers to increase the ‘greenhouse’ effect, and to protect early shoots from frost nip (a very deep or prolonged frost will penetrate an un-heated poly tunnel or greenhouse.
A light watering once a week during winter is sufficient but then I put the containers in a watering tray as the poly tunnel warms up in spring.
12th April, just as other people are chitting their seed spuds, and I already have healthy, vigorous plants.
Four large plant pots of healthy spuds ready for harvest. Photo taken 3rd June. These are ‘Charlottes’.
You can see here the last of my pink fir apple pot grown spuds is about to be harvested just as the cucurbit seedlings are ready to plant out.
I empty the compost onto a sheet so that I can rake through and remove all those tiny spuds which turn into ‘come-agains’ in your allotment, popping up amongst other crops. You don’t have that problem with container grown spuds as its much easier to find them
Crop sizes can vary enormously depending on weather and sunlight.
A harvest of ‘Charlottes’ on the 21st June 2016
The same harvest as above, cleaned up in rain water.
Another harvest on the 28th May 2015
The same harvest on the scales. Conditions must have been just right because I got nearly 2lbs (900g) from a single plant in May.
Summary of advantages of poly tunnel/greenhouse container grown spuds:
A – An early crop
B – Combined with outdoor spuds gives you a longer season
C – Makes good use of dis-used winter pace in poly tunnel/greenhouse.
D – Can be moved around or even outside if the weather is good.
Give them a try. Plant anytime from November to the end of March for an early crop of any potato. You don’t have to use an early variety.
And you don’t have to stop there.
My first experiments were with winter crops but if you plant seed potatoes in containers in a poly tunnel or greenhouse, at the same time as your outdoor planted seed potatoes then you will crop them weeks earlier, and you will give them greater protection against blight. Personally, apart from a few experiments I haven’t continued this practice because I have plenty of outdoor space and I like to use the poly tunnel and greenhouse for other stuff, but it’s an option.
I am a beekeeper and an allotment grower and this site features articles on those subjects including recipes made from the produce from my allotment and from my bee hives. I have an interest in a great many things (too many actually) and some of those experiences, and the joy and learning I acquire from them, may also randomly appear here.