Tomatoes in grow bags: how to drain?

I am confused.

I have grown tomatoes in grow bags for many years now and have always, without thinking, punctured several drainage holes directly underneath the bag.

Why do I do this? Because all gardeners know that unless you’re creating a pond, you need drainage holes – good, big ones! – or your plants will quickly turn to a waterlogged mush and will be ruined. We just know it.

Therefore, it came as some surprise to me this morning when, for once, I actually bothered to read the instructions on my grow bag (a Levington Tomorite Giant Tomato Planter) that it specifically said NOT to make holes in the underside of the bag but to put them halfway up the side.

Really? But?…but?…won’t the roots drown and my plants die a sodden death??

Clearly the makers of grow bags know less about how best to use their product than I do (!) so I was about to ignore them and reach for the scissors when it occurred to me to read the instructions for the growpots that I like to use along with the bags and discovered that they too recommended NOT making holes in the underside of the bag but halfway up it instead, as per the following diagram:


I then went scouting round the internet to see if I could find a consensus of opinion but came back none the wiser. Some people advise making holes in the base of the bag, some don’t. Helpful!

So what have I decided? I’m taking a deep breath, crossing my fingers and doing it the makers’ way by putting the holes halfway up the bag – yikes! It goes against all my instincts and I am already convinced that my plants will keel over by July, but nonetheless, if I don’t try it I’ll never know!

The tomatoes, newly planted up – “Sungold” at each end and “Matina” in the middle:


To make this a fair test I will of course be adhering absolutely to the watering regime suggested by the growpot manufacturer, which goes as follows:

  1. On planting, water inner pot with 0.5 litres and outer trough with about 2 litres.
  2. For the next two weeks, do not water the outer trough (I am presuming I can water the inner pot if it looks very dry??)
  3. For the next 3-4 weeks pour 1 litre of water into the outer trough every 2-3 days. The inner pot should not be allowed to dry out and should be watered at least once a week.
  4. When plants have matured the outer trough may need filling with water every day depending how hot and sunny it is.
  5. To check for over-watering, one should squeeze the bag close to the drain holes and if any seeps out cease watering for a day.


Feeding should be done according to the feed instructions, applying it to the inner pot.


It does seem a bit hit and miss to me, but we’ll see!



Posted on May 16, 2014, in Techniques and tagged , , . Bookmark the permalink. 2 Comments.

  1. nick pettyfer

    As co-designer and tester of the original grow pots( the pots with the serrated cutting ring),I can assure you that your plants will do just fine.If you have any questions regarding the original grow pots you can email us at

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