Potato Grow Bags: The Real Story

Here’s the real story about how to successfully use potato grow bags.

I’ve been growing potatoes in the ground for years and this has always resulted in an edible crop. Whether the potatoes were small or large, depended on the quality of the soil.

In heavy soils such as clay, I would end up with smaller potatoes but in more sandy soils, the potatoes would be larger as it was easier for them to grow in the soil.

What I didn’t like about growing potatoes in the ground was the fact that once you’ve grown potatoes in a certain spot in the garden, you would always end up with a crop the next season whether you wanted them to grow there or not.

So, a couple of years ago, I decided to give potato grow bags a try. While the results were not what I expected, I did end up with a decent crop.

My Expectations Of Using Potato Grow Bags

I’m sure you’ve all seen those lovely photos on Pinterest where when you open the flap, potatoes just come tumbling out. And, that’s kind of what I was expecting. So, as I gently opened one flap, you can imagine my disappointment when there were no visible potatoes even though the plants had been growing really well.

I opened the other flaps and still no visible potatoes.

Then, I had a dig around in the soil in the bag and finally, I found quite a few lovely potatoes. So, what had I done wrong? I thought about it for a while, and then the answer hit me. I can’t believe I hadn’t realised this at the outset. But, as I always say, gardening is an adventure and we’re all amateur scientists.

Why Were My Expectations Not Met?

To understand why I didn’t get the results I was expecting, I had to think about how potato tubers grow. You see, the tubers grow very close to the base of the plant.

Potato plants don’t generally send down long roots from which the tubers then grow. If you’ve ever grown potatoes in your garden and then dug up the plant, you would have noticed that all the tubers were close to the base of the stem.

So, what I discovered was that I just hadn’t planted the seed potatoes deep enough into the grow bag to then have new tubers tumbling out of the flaps.

Another thing that I realised was that if you buried more of the stem in the soil, more tubers would grow from the stem that was buried in the soil.

That’s when I had that aha moment and realised how growing potatoes in bags of soil could be really beneficial and produce quite a decent crop if you do it right.

So, here’s my guide to growing a bumper crop of potatoes using grow bags.

Don’t Fill The Bag With Soil

When you get your brand new potato grow bags, don’t get overenthusiastic and fill the bag with soil. You only want to add around 7.5 cm (3 inches) of soil into the bottom of the bag. You can roll down the sides of the bag to make it easier to get to the bottom of the bag.

Once you have a layer of soil in the bag, plant your seed potatoes into this. You don’t have to plant them very deep as you only have a shallow amount of soil to work with.

Add More Soil As The Plant Starts To Grow

As you notice the tubers sprouting and you have some green growth above the soil, you want to add some more soil to partially cover the emerging stems of the plants. Don’t cover the green sprouts totally because the plants do need sunlight to grow.

Essentially, you want to bury around half the emerging stem in the soil. So, if your plant has grown to 15 cm (6 inches) high, add more soil to cover around 7.5 cm (3 inches) of the exposed stem. You can even go as far as adding enough soil so that only the tips of the plants are showing.

Make sure you keep the plants well-watered at the same time. Potato grow bags are naturally self-draining so your plants won’t have to deal with wet feet.

Continue to add more soil as the stems grow ever upward. You can start to roll up the sides of the bag as you do this in order to contain the soil.

Keep Adding Soil Until You Reach The Top Of The Bag

Over the next few weeks, continue to add more soil into the bag, covering around half the stem each time. You can stop once you reach the top of the bag.

If you do this, you should end up with new tubers growing not only at the bottom of the bag but also right throughout the entire contents of the bag.

And, if you want a bag full of potatoes, make sure you plant multiple seed potatoes in the same bag. You can even mix up the varieties and have a mixture of different potatoes all growing in the same bag.

Growing potatoes in these bags also means that you can use the bags for other plants after the potatoes have finished. All you have to do is tip the soil from the bag into a wheelbarrow or garden cart and rake through it thoroughly to remove any tiny tubers that you may have missed while harvesting your crop.

You can reuse the same soil but I would mix it with about the same volume of new, fresh mix or compost in order to freshen it up. If you do this, you’re going to have enough soil for two bags instead of one!

Frequently Asked Questions

How many potatoes can I grow in a single grow bag?

At a minimum, I would plant around 6 seed potatoes in a grow bag to get a decent crop of new tubers.

What size grow bag should I use for growing potatoes?

Currently, I’m using bags that are 40 cm (16 inches) in diameter and 55 cm (22 inches) high.

When should I plant potatoes in grow bags?

The best time to plant your potatoes into grow bags is late winter or early spring.

How often should I water my potato grow bags?

This will depend on whether you receive any rain or not. If the weather is dry, water your grow bags at least once a week and ensure you give the soil a good soaking.

What kind of soil should I use for growing potatoes in grow bags?

Whether growing in bags or pots, you should always use a premium potting mix as this is the right consistency and also contains nutrients. If you have your own compost, you can mix this with the potting mix in a 50:50 ratio.

How deep should I plant potatoes in a grow bag?

As I’ve already explained, you need to plant your potatoes really deep in the bag or in the bottom 7.5 cm (3 inches) of the soil.

Do I need to fertilise my potato grow bags?

If you’re using premium potting mix with compost, you shouldn’t have to supply your plants with any additional fertiliser. However, if you’re reusing potting mix, add some organic fertiliser pellets to the mix before putting this into your grow bags.

Can I reuse grow bags for planting potatoes?

It’s perfectly fine to reuse your grow bags the following season for growing potatoes as long as you refresh the potting mix as I’ve outlined above.

How long does it take for potato plants to grow in grow bags?

Generally, it will take around 3 months or 120 days before you can harvest your potatoes. In saying that, you might be able to harvest some smaller tubers before this.

Should I cut off the foliage of my potato plants when they start to die back?

This is not necessary because once the plants die back, it means that the tubers are ready to harvest. When this happens, it’s just a case of tipping out the bag, discarding the foliage, and harvesting all the tubers.