My dragonfruit is like 12 feet (3 metre) high now and still has no air roots, it grows against a live tree.
Also somewhere i read about plastic as fertilisers. Decomposing plastic used as fertilizer so maybe they can "eat" the pvc-pipes?
Sure. Want to wait a few million years? it could world. Also, some of the stuff in there you don't want getting out. That's why you should buy food grade.
Food grade plastic? I have never heard of that.
Here in Thailand if you have plastic bags or buckets and let them be in the sun then after a few months they are totally decomposed. You can't even lift the bucket no more. (cheap buckets). also plastic bags totally disappear in the sun. I won't say they are good fertilizers though but i really read some sites where they talk about plastic fertilizer.
http://turf.arizona.edu/tips1094.html Plastic coated fertilizers have been developed in the last 5 years. The break down of the plastic film determines the rate of fertilizer availability. Although all slow release nitrogen fertilizers have the same goal of limiting the speed of nitrogen to turf, the way they become available differs
Here a site about plastic mulch, (whatever that might be)
http://www.ehow.com/how_5789797_fertilize-onions-under-plastic-mulch.htmlThe plastic bags here in Thailand are used for really everything (to sell coca-cola in for example) , you get them for free and they don't last long. I guess biodegradable plastic is to expensive for the Thai and also they don't care at all about environment. My wife just trew old battery's in the binbag, they don't even have collecting points for them.
But i guess you are right, i got confused by terms like plastic mulch and plastic fertilizers.....