Best grow bags
Growing bags are popular with gardeners - and for good reasons. You don't need a pot as you can plant directly into the bag and for tender crops they're a great alternative to planting in a greenhouse border. They're a bargain option, too - often costing less than bags of multipurpose compost.
But not every bag is as great as it sounds, which is we decided to test them for you. We trialled 11 peat and peat-free growing bags to find the best for growing summer veg, such as cucumbers, tomatoes, aubergines, chillies, peppers and melons. The best produced lots of large, healthy summer vegetables, while the worst made inadequate yields with pale leaves.
Best grow bags
Why Which? grow bag reviews are better
Before testing, we send out four secret shoppers to buy all our grow bags so we know we're getting the same product as you. The shoppers buy two of each, making a total of eight of each brand, to see if there are any variation in the quality of each bag.
We sow seeds of cucumber ‘Carmen’, a standard-sized cucumber, which grows fast and produces good harvests. In late May, when the plants each have five leaves we plant two into each of our growing bags. We grow them in a greenhouse, trained up wires and removed sideshoots below the fruit.
We link each growing bag to an automatic watering system, so all the bags receive the same amount of water, and feed them with a liquid fertiliser.
We grow and pick the cucumbers twice a week. We weigh and count the harvest from each bag over an eight-week period, noting if any are bendy, bulbous or have rough skins. At the end of the test, we harvest, weigh and grade the remaining cucumbers for size.
How to use grow bags
- Wait until your young plant reaches 15cm high.
- Shake the grow to fluff up the compost.
- Make some cuts in the bottom of the bag to allow excess water to drain out.
- Cut along the marked lines on the top of the growing bag to position your plants.
- If you only want to put two plants in each bag, use the two outer-planting positions on the bag.
How do you water plants in a grow bag?
- Water regularly so the bag doesn’t dry out. In hot weather, this may need to be up to three times a day.
- An automatic watering system with a timer will help to avoid dry plants.
- Most summer veg will be in the bags for many weeks, so you’ll need to feed them. Either add controlled-release feed by mixing it into the compost where you have cut holes before you plant, or liquid feed twice a week once the first fruits have formed. Follow the dosage and frequency advice on the bottle.