Your idea of growing sweet potatoes in grow bags is one that I will also try. I have never had a lot of success with sweet potatoes, which is difficult to understand as they are one of the better crops for our hot summers.
I seem to get a lot of leaf growth and little tubers. I know that this can be from too much nitrogen, but in my impoverished soil I find it difficult to believe that my soil is too rich for SP's. I'll try the grow bags, it maybe that I haven't given then sufficient water, and the grow bags may help there. What type of soil mix do you use in the grow bags? Fertiliser? How often do you water? At this time of year I can grow Yams for starchy food, but I'd much prefer SP. The yams are quite limited in how you can use them.
I've used many different forms of mix to fill the bags. Pretty much some variation each time. A bag of Searles potting mix worked fine. I randomly add "stuff" like Organic Xtra. Lately I have been using a bag of the composted horse poo and the results are good. So this would lead me to think that a richer soil is better....but then I have had good crops from the potting mixtures too, but they are way more expensive than the $3 bag of manure.
I've found they like their water. I can neglect this but I suffer the consequences with a poorer crop (I think! - it's only been a few years I have been growing like this). Because they are in the grow bags watering is pretty easy. I just make sure I give the whole thing a good soak maybe two or even three times a week. Depends on how often I am out there with the hose keeping seedlings moist.
Yams are Yucky. Too slimey for me. Swt Potato are nice and dry.
Thanks for the info Lissa. I will try with horse manure and my sandy soil, they are both free and as long as I include the horse manure it seems to work. The sand by itself is hydrophobic, but with manure added it gets better as time goes on, especially if I keep the mix a little damp all the time. I am hoping that the grow bags will aid with this. Worth a try!
Roger, Dave Riley gardens on pure sand. His many posts on BLF have told us a lot about what works for him. Currently he's finding mounds are giving him good results.
For a time there I sifted sand with horse manure 50:50 and filled a bathtub with it to grow sweet potatoes! It worked, but it wasn't a great harvest. So I''m back on the dirt making bigger mounds and playing with other options.