Here are my favourite "Grown-up" garden books- I have another page with the ones for gardening with kids :)
Square Foot Gardening:
This is a great book about an intensive gardening technique using 4 foot square raised beds. The beds look very nice! This is my particular favourite method, because consistently it looks good and is easily manageable.
Lasagna Gardening: This one and the ones that follow are a series of books that detail a 'lazy gardener' method of gardening... no till, just build 'lasagna' layers of organic ingredients on TOP of your soil and plant your garden inside it! It is kind of building a compost heap into a bed- it is a very effective method.
Lasagna Gardening with Herbs:
Describes how to use the methods in the book above specifically for herbs- includes some garden ideas.
Lasagna Gardening in Small Spaces:
Describes the same techniques above, adapted for smaller gardens and containers.
Four Season Harvest: This book details methods of extending your growing season... cold frames, greenhouses and so on. For the experienced gardener.
How to Grow More Vegetables and Fruits: Another intensive gardening book, this one details more conventional beds which are 'double dug'. A LOT of work goes into this, but it is certainly the cheapest method of soil improvement. What makes the book GREAT though, are the detailed planting guides inside AND the garden plans!
Designing the New Kitchen Garden: An American Potager Handbook
This is more about designing the potager (pronounced pot-ah-zhay) than planting the garden! The gardener's eye candy inside is great for those winter days when you just can't get outside!
Weedless Gardening: Another 'lazy gardener' technique. Reich details the methods (plural) which can be used to make your garden less labour intensive.
Compost Gardening Guide:
This lovely book has some wonderful composting techniques and tips- well worth the read :) It has the added advantage of being new enough to have all the up-to-date changes made in the world of 'recycling' - which is what composting really is!!