That's not strictly correct - I've seen some stunning turnery from Leylandii, Macrocarpa, Chile pine and even larch. Ordinary spruce, fir and pine won't get you far, however. Don't waste your time practicing on rubbish, it's soul destroying and more likely than not to put off rather than encourage you. Some timbers are difficult to season without staining - sycamore and holly being two, and some are difficult to season without their splitting - cherry, damson and some other fruit woods. You can of course part turn green and then season. You really need to get some reference books if you visit Amazon, Waterstones Marketplace etc. you can pick decent books up quite cheaply. If you're actually felling, winter's the time - the sap is down. Ultimately suck it and see - If you cut it up and it looks to have interesting grain or colour, paint the end grain with something - candle wax, old paint, PVA, whatever comes to hand - and store it. Don't be put off by bits of rot, bark inclusions and cracks - turnery from perfect wood is often boring.
