Allergy-Free Gardening: A Revolutionary Guide to Healthy Landscaping by Thomas Ogren (Ten Speed Press, 2000) lists hundreds of plants that are 100 percent pollen-free. The book also contains listings of thousands of common landscape plants which are ranked 1-10 for their ability to cause (or not to cause!) allergies. Ogren dedicated fourteen years to the development of his innovative scale of the relative allergy risk of common landscape plants. This is a great guide for anyone with asthma or allergies who is interested in landscaping or gardening.
Clever Gardening Technique
Pinch Back those Seedlings
Last year I got a little impatient when starting my impatiens. I sowed the seeds too early and had flower buds starting to form long before spring. So I pinched the buds off, then pinched good-sized stems from the plant and set them in cups of water. Over the next two weeks, the original plants grew bushier and the pinched stems rooted in cups of water. For all my impatience, I was rewarded with a double crop by the time I was ready to plant them outdoors. This method should work for other annuals, as well.