Rooftop | how to grow spuds in pots
Potatoes are cheap to buy and bulky to grow, so why bother if you have a tiny urban garden? I’d say it’s worth it because it’s really satisfying and it gives you the chance to eat exotic heritage varieties you’d never find for sale in the shops. You don’t even need that much space – a container 30cm deep and wide is enough, though the bigger the pot, the bigger the crop.
I’ve grown spuds on my small rooftop in north London for the last two years. My approach has been experimental and I’ve learned from my mistakes. You really only need to plant a few seed potatoes in a dustbin-sized container – plant too many and your spuds won’t have enough room to grow.
I’ll never forget the day I harvested a home-grown heart-shaped potato – the joy was immense. I gave it to one of my best friends as a birthday present. And last year I grew the ‘Purple Majesty’ variety – the potatoes had beautiful metallic skin and deep indigo flesh that retained its purplish colour on cooking. The lush and bushy potato plants turned my roof into a miniature jungle, and had beautiful purple flowers.
I’ve planted potatoes in a hessian sack lined with a plastic bin bag, and even in one of those boxy hessian shopping bags you sometimes get in the supermarket. This year I’m going to try growing some in an upturned wicker cat travel basket I found discarded in the street. It’s compact, but also suitably deep and wide.
The first thing to do is to choose your variety and then buy it in seed potato form. Your haul is going to be small, so make sure the spuds themselves are particularly spectacular. Look out for local potato days and seed swaps, visit your garden centre or order online. Try Alan Romans’ good value online shop for interesting heritage varieties. ‘First earlies’ (planted around late March) and ‘second earlies’ (planted early to mid-April) are meant to be best suited to small spaces.
Things you’ll need
1. Seed potatoes
2. An empty egg box
3. A deep container (at least 30cm deep and wide, bigger is better) – this could be a purpose-bought or homemade container, or it could be a hessian sack lined with a strong bin bag
4. Vegetable compost
5. A trowel
Step by step
1. Buy your seed potatoes. You won’t need many – perhaps two or three for a 30cm x 30cm container and up to five for a planter that’s the size of a domestic dustbin.
2. You need to start your spuds sprouting or ‘chitting’ indoors before you plant them. An empty egg box is great for this, as a seed potato can sit in each compartment. Stand the spuds on their bluntest-looking end in the box and leave them in a dry place with lots of natural light. Mine sit happily on a bookshelf. After about six weeks they should be sporting 1.5–2.5cm sprouts and be ready to plant out.
3. If you’re planting your spuds in a hessian sack or bag, you will need to line it with plastic. A strong bin bag or an empty compost bag works really well. Make sure you punch holes in the bottom of the bag so water can drain out.
4. Half fill the container or lined sack with good compost. I use New Horizon Vegetable Compost, which is organic and peat-free. If you’re working with a lined sack, you might find it a bit floppy at this stage. I put a cane in each corner to make it sit upright and open. These canes will later provide support for the potato plants.
5. Plant the sprouting spuds about 7cm deep, water and wait. After a few days you’ll see sprouts emerging. Cover them with another layer of soil, so the sprouts are just buried. Repeat this every time you see sprouts poking through the earth, until your container is full. Don’t over water, but make sure the soil doesn’t dry out.
6. The potatoes will grow into big bushy plants and they may well flower and fruit (take care though – the fruit is poisonous). Depending on the type, the potatoes will be ready to harvest about 10 to 16 weeks after planting.
7. You can gently root around in your container to get a sense of what’s going on underground. If the spuds are still tiny, you’ll know to leave them for a while. Use hands not tools, you don’t want to damage your growing spuds.
8. ‘First earlies’ often need to be harvested while the plants are still looking healthy, just after the flowers open. ‘Second earlies’ can stay in the ground much longer, until the point when the plant above ground is dying back. One method of harvesting container spuds is simply to tip the soil out onto a sheet and hunt for the vegetables. This is fun but pretty messy!
This article was originally written for City Planter.