How long does it take to develope a "green thumb"   

That is a gorgeous and healthy looking sunflower. I had to learn as well so what I did was read and I started with plants that were hearty. I still continue to read about gardening and each year I get better at it by trying more things and spending more time on it. Just continue to enjoy it, maybe do some reading up on plants that you would like to have (or already have) and take it from there.

All I can really say is practice, practice. I grew up always helping my mother with the gardening each year, so I really paid attention to what she was doing, as time went on I started to develop my own ways of gardening. In which most have been successful.

No matter what the type of soil you may have I have always made it a thing to get potting soil and mix it into the ground along with a quanity of plant food and small pebbles. (The pebbles help with drainage so your plant isn't getting over watered or sitting in a pool of water) When I repot indoor plants I also place a layer of river rocks (can be bought in any craft store or pet store located in or near the area they have fish displayed) on the bottom to help with drainage and I never keep my plants sitting in water. Yes you have to water a little more, but with most plants they can drown by intaking to much water.

In most instances it is good to get to know the plant inside and out, learning everything you can about it. Mainly how much water it needs, how much plant food you need to give it, how much light it needs, and what type of soil your plant perfers to grow in. Generally keeping these things in mind, you'll end up with healthier and happier growing plants.

It sounds like a lot of work, but really it's worth it once the plants start to grow and you end up with a beautiful garden or a houseful of lush green plants. Good luck with your garden.

I am on my eighth year of gardening. I love it and try to get as much information as possible about it. But still I kill a lot of things and when I do I try to figure out why and hope I have learned a little more for next year.

It is a trial and error thing for me. I really do love to get out there and plant things. When I find things I repeatedly kill, I skip them for a while and try later.

I try to blame it on the dirt so I always come out looking like I knew what I was doing! That way I trick my self into thinking I am a great gardener. We really do have bad dirt now and then...

Well.. I think you either have a green thumb or ya dont.. but if you really want to learn, I would suggest reading up on whatever it is you want to plant. I've done great by starting out with easy to care for plants then branching out to the more difficult ones.