Grow bags are an easy and convenient way to grow plants with minimal fuss and provide all that your plant should need to produce a bountiful crop. Make sure you give your plants the best care by ensuring it has good access to water.

How much space do plants need in a grow bag?


It’s important to make sure you don’t put too many plants into your bag. They are full of all the best nutrients for your plants, but if you put too many in there, the roots are going to be competing and the grow bag will not be able to support them all. Often, the bag will say how many individual plants you are meant to grow in it, which is a helpful rule of thumb, but typically, stick to one or two plants.

You want to make sure that each plant has plenty of room to grow and support its own root run.

If you haven’t got room to use a grow bag in its original shape, don’t worry, you can still grow multiple plants and you won’t need a pot. Just cut the grow bag in half and stand each half up as an individual bag.

How much water does a grow bag need?

This can vary by the size and plant within the grow bag. But generally, once you have planted your plants, you need to water the grow bag liberally. These bags are designed to be well-aerated and well-draining, so in the heat of summer, they need watering daily.

A good way to double-check whether your soil needs watering is to feel it. Get your hands dirty, and if it feels dry, then it probably needs some generous watering. If it feels quite wet, then you may need to leave it and check it again the following day.

How to retain water in a grow bag

If you are using your grow bag outdoors, make the most of natural watering through rain, which we have plenty of in the UK.

When you plant your tomatoes in the grow bag, cut a square of plastic out of the top. The bags will often have these pre-marked at the top for you to follow. Don’t cut it all the way, leave one side still attached to act as a hinge. Cut a slit in the ‘lid’ to leave room for your plant stem to grow, just like I’ve done with this Miracle-Gro® Tomorite bag.

By keeping this part of the plastic, when the weather is a little dryer and you have just watered your plants, the bag can retain the water, losing less by evaporation. Plus, if you leave your grow bag outside, you can tuck the lid in so the bag can collect water naturally through the rain.

If you have them, place the bag in a watering tray. This will retain any water that doesn’t fall into the grow bag itself.

You can place fleece in the bottom of your watering tray to soak up some of this water, so your grow bag isn’t left sitting in standing water. You want to avoid this, as it can cause issues such as root rot. Don’t worry if you don’t have any fleece, you probably have plenty of absorbent materials that you aren’t using, such as old tea towels and bath towels.

Tomato plants in grow bags, open for watering

Give your plants the nutrients they need by feeding with the right fertiliser at the right time. Your plants will appreciate it and reward you with flurries of flowers, fantastic foliage, and great harvests.

Find out more about growing in grow bags:

Or check out my Pinterest board for more ideas: