Here are some of my favorite garden magazines:
Fine Gardening is my favorite. It has a good plant reviews. It also sometimes has very interesting gardening plans such as build a patio in a weekend, build a cold frame or build a unique water feature from old issues I own. I love the captivating combination section where they pair plants for impact
Garden Gate is a great mag too. I like their tips and before and after gardens. I love this months section on pruning.
The Herb Companion has lots of tips on growing herbs and incredible recipes.
Organic Gardening is pretty cool. I am not really an organic gardener but it has tips that are great for everyone.
Hobby Farms is a very good magazine. I only get it occasionally if it has something relavent. I loved their issue on raising lavender. They also have good recipes.