Hi In some cases I'm going to use terracotta pots for indoor plants, but also I'm going to use containers I've built myself -- small boxes with drainage, in which I'll have added a few worms. Question: What is safe to use as a liner and sealant to waterproof those boxes. I'd like to avoid plastic because it leaches. I don't trust glues generally, and I'm not sure about silicon either. Short of cooking up a big bowl of pine pitch in the back yard, for filling cracks and offering some protection for the wood, I'm stumped. Thanks in advance for any opinions or advice.
there is a product sold in garden centers as "pot sealer" sold by the pot manufacturers and supposedly quite safe. Not us reif its sold in your location listed as 4A, but it is available here in BC.
Chiming in a little late here, but why do you really need to waterproof either wood or terracotta? If you have drainage, the pot itself does not really get wet, certainly not wet enough to cause damage. Neither container will last absolutely forever, but long enough. Filling cracks in the wood is a slightly different matter. I'd suggest modifying your design so you don't have cracks if possible. If not, then make the soil in the pot dip toward the centre, so that when you water, the water soaks into the soil rather than running down the sides of the box and out the cracks. In all cases of course, indoors that is, you need trays under the pots and boxes to catch any overflow. That's why I don't grow any indoor plants :-)
Never too late to chime a bit; thanks for the help. If I originally said I wanted to waterproof terracotta, I'm not sure what I was thinking, I've got a Norfolk Island Pine and Pica in terracotta here... But I was thinking of taller wooden structures in which to keep a few worms, be able to feed them (the design allows for soil removal and sifting once in a while) which are open at the top, for growing herbs, or winter cat grass. Worms like to stay wet, and I was just thinking in terms of wet soil without so much drainage. Very much still in the planning stage, so any advice is welcome. Thank you for yours.
I agree with late chimer, but you may consider the following course of action for maintaining an earth worm friendly environment...cut a 2 or 4 litre plastic container in half to form an open sided vessel/dish, place or somehow try to fit , convex (to catch the moisture) a few inches below the soil surface medium of your pot , place a water meter into convex container and keep this moist for your worms, at least they will have a "moist shelter" for the dry spells...also try to place another at the bottom of the pot (creates two worm zones for better survival) a little mulch on the above to prevent premature drying out and voila, you have an indoor worm farm, which will keep you busy, but don't forget to keep your Norfolk Pine happy too! Have I tried this? No but good luck! And happy container gardening. Look up worm farming...?