For some grow bag might not be a new idea but to some it is yet to be discovered even though they are in use since 70’s. Grow bags are like their name are bags that can grow and many of us DIY gardeners have made or used any such homemade pots like the newspaper small seedling pots. You can use your vegetable bags, fabric based bags or simply make one yourself the idea is to use something that lets air gets in but doesn’t let the potting soil out.
Why Use Grow Bag
Grow bags are made using felt or other form of fabric that can hold potting medium. The idea is that the entire lining of the grow bag needs to be porous facilitating aeration to take advantage of root’s air pruning.
What is root pruning?
Imagine if you cut the stem at the top of a tomato plant, the plant will then grow more shoots along the sides of its main stem, Similarly when you prune the root of the plant at its tips it produces more fibrous roots from that root’s sides and those fibrous roots are the feeder roots. Plants absorbs nutrients from those feeble tiny root nodules.
Root Air pruning
Air pruning is simply pruning by exposing the roots to air, In this form the roots are exposed to air gradually unlike the cut of a pruning sheers which does not put the plant in stress. Grow bags facilitate in this regard when the plant’s root come to the edge of the grow bag they are pruned unlike in plastic or terracotta pots. This results in more fibrous roots which are capable of using water and fertilizer better than the plants in plastic pots. This also makes it possible for you to grow bigger plants in smaller containers which could be a big plus for most of us Urban gardeners.
Below are the images I took before replanting my pepper plant of an year old in a 3 gallon terracotta pot, look at the roots and how they traverse through the pot.
It is a bit difficult to see roots in a felt grow bag without cutting it out but I hope following images will show you the idea.
Above is an year old eggplant that isn’t producing well now when I tried to get it out of the grow bag the root ball broke in the middle, over all there aren’t many roots you can see that is because the roots are very very tiny and there aren’t any roots traversing the grow bag. By the way this and my two other eggplants are in 5 gallon grow bags, This one stopped producing this year but the other two have done really well I harvested 2-4 eggplants from each.
Grow Bags, The down side.
Grow bags do have their disadvantages. Let me tell you what I have learnt so far:
- You’ll need to water them more because they tend to dry off in summer.
- Grow bags, even the black ones are not that good at keeping heat then their fellow plastic pots.
- Water run off can create a mess so I would advise to place them accordingly or to use a tray.
- Sometimes, so it happens that the water just comes out of the fabric instead of penetrating the soil, The remedy is that you use a shower to water it lightly and then stop perhaps water your other plants and then come back again water a little and so on and so forth or simply, use drip irrigation system.
- You will also need to use more fertilizer which you can even find on many fertilizer’s “direction to apply labels” reason again is, water run off which also leaches that fertilizer with it.
- Grow bags might not be the best option to be used in very hot climate or season. However a drip irrigation system can solve you many problems.