Horticulture Magazine

How To Grow Potatoes In Grow Bags

three large sacks with potato plants growing from them in the garden

Potatoes are a staple crop that can be great for home growing but they can take up a lot of space, so growing in grow bags or other containers can be a good option for small space growers.

Potatoes can be grown in a range of different ways. You do not necessarily have to have a large garden to grow some potatoes for yourself and your family. Using grow bags of some kind could be a good way to get started.

Growing potatoes in grow bags or other containers allows gardeners to make the most of their space. Grow bags in this context refers to any fabric bag which can be filled with your growing medium.

Why Grow Potatoes in Grow Bags?

close up of potato plants growing in a bag
  • Grow bags (like other containers) help you grow more food in less space.
  • They are less likely to have water retention issues than many other container options.
  • Root compaction is less likely to occur when growing in grow bags.
  • Grow bags can be lighter and easier to move around than other containers.

However, grow bags are not always the most sustainable or eco-friendly choice when you buy them new.

You need to think about what they are made from, where they come from, how long they will last and what will happen to them at the end of their useful lives. Reuse is always a good strategy in an organic garden.

Another thing to bear in mind is that grow bags can dry out more quickly than other types of containers. So you will need to be particularly careful to make sure that your potato plants get the water they need.

Choosing Grow Bags (Or Other Containers)

There are many grow bags that can be purchased, both non-sustainable plastic options and more sustainable fabrics like hessian or hemp.

Plastic (synthetic fabric) bags will last longer, as they will not break down. However, they also, of course, come at a huge cost – utilising fossil fuels that should be kept in the ground.

Fortunately, you do not have to shell out on a new grow bag for your garden because there are a wide range of reclaimed materials that you could use.

Even if you are trying to avoid plastic use as much as possible, you may well have large plastic sacks from compost or other materials you have bought in for your garden. These can be used as grow bags. Reusable shopping bags might also be used to grow potatoes.

On a larger scale, you might reuse the large bags used to transport building materials. You can also make your own grow bags out of old clothes, bedding or other reclaimed fabrics from your home.

Remember, grow bags are not the only option. There are also a range of other reclaimed containers to consider. Some potatoes, which will be ready more quickly, could even be planted in a sturdy cardboard box.

Filling Grow Bags for Potatoes

A simple multi-purpose peat free compost will be fine for growing potatoes. You can also use a homemade mix of homemade compost, soil/loam and organic matter like leaf mould, for example.

One other interesting thing to consider is that you can fill your bags with layers of organic material – just as you would in a compost bin or no dig lasagne garden. Again, it can often be more eco-friendly and sustainable to take a DIY approach rather than buying in materials.

When growing potatoes in grow bags, you will not fill the grow bags up to the top as you would for most other plants.

Instead, you will fill the grow bags only to a depth of around 10-15cm, then top up around your plants as they grow. We’ll take a closer look at this a little later in this article.

Choosing Seed Potatoes

Potatoes in the UK are usually divided into three categories:

  • First earlies – from 10 weeks to harvest.
  • Second earlies – from 14 weeks to harvest.
  • Maincrop – 20 weeks or longer to harvest.

Though maincrop potatoes can be grown in grow bags providing these are of sufficient size, first and second earlies are generally the best options for grow bag gardening.

Planting Seed Potatoes

three seed potatoes in a grow bag

As a general rule of thumb, you can plant 1 seed potato for every 10 litres of capacity in the grow bag you have chosen.

So for a grow bag with 40-litre capacity, you can plant 4 seed potatoes. This can vary quite a bit, of course. But this is a rough guideline to help you think about how many potatoes the containers you choose can accommodate.

Seed potatoes are usually sown in spring. However, when growing in containers there is also the option to sow second earlies in June or July for new potatoes around Christmas.

You simply need to make sure that you give some protection to the plants before the first frosts arrive, or move your potato grow bags undercover into a greenhouse or polytunnel.

First of all, place some of your growing medium in the base to create a layer for the roots around 10-15cm deep.

One handy hint is to place a piece of turf upside down in the base of each to act as a sort of sponge to retain moisture. I also like to add some comfrey leaves or seaweed as I plant my potatoes to get them off to a good start.

Place your seed potatoes on the surface of this bottom layer and then cover them over with another 15cm or so of growing medium. Water them in well, and wait for the shoots to emerge, making sure that you keep the grow bag moist but not waterlogged at all times.

Earthing Up & Mulching

gardener topping potatoes with extra compost

Once the shoots of the plants are around 15-20cm above the surface of the growing medium in your grow bag, you will add more growing medium or organic material around the plant as it grows, layer by layer, until you reach the top of your grow bag.

The purpose of this is to encourage new roots and tubers to form from the portion of the stem of the plant which is covered up.

Traditionally, when growing in the ground, gardeners will ‘earth up’ their potatoes with topsoil. But you can also use homemade composts and all the organic materials that you can put in a composting system.

Mulching with organic materials (in layers of brown carbon-rich and green nitrogen-rich materials) rather than using soil or a more conventional growing medium can also yield good results.

Caring For Potatoes in Grow Bags

Watering

Remember that potatoes in containers will typically require more water than those growing in the ground and grow bags can sometimes be even more prone to drying out.

Make sure you ensure that the growing medium is moist throughout the growing period.

Feeding

For best results, feed potatoes in grow bags with a good quality organic plant feed two or three times over the growing season. Compost tea or seaweed feed can be made at home for this purpose, so you should not have to buy anything in.

Harvesting Potatoes in Grow Bags

It is not always easy to tell when potatoes are ready to harvest. Some plants will have tubers ready to harvest once they flower. But some will not flower at all.

So the best thing to do is simply to feel gently in the growing medium to feel how large the tubers are. If you can feel some tubers that are of a worthwhile size, you can harvest a few at a time by feeling around the edges of the plant in your grow bag. Or you can tip up and empty out the whole grow bag to harvest your crop.

Remember to use the right storage techniques to keep your potatoes in a good condition after harvesting.

You likely won’t get as many potatoes from grow bags as you can from plants grown in the ground in optimal conditions. But if you have cared for your plants successfully, you should not find the yield from each grow bag disappointing.

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