A soil test recommended adding a lot of phosphorus to my new shrub bed this spring. The soil was very low in phosphorus, and I worked it in well before planting. Should I add more this fall?
It's good that you thoroughly worked the phosphorus into the soil, because phosphorus is one of the big polluters of the Chesapeake Bay. It's important to prevent it from being washed into storm drains or waterways that lead to the bay. Phosphorus binds with soil and is not volatile like nitrogen, so the full application you already made should suffice for years to come. Repeat the soil test in three to four years.
I have dahlias growing in a pot outside. Instead of removing the rhizomes this fall, storing and replanting them in the spring, can't I just store the potted plants indoors over the winter?
It may be possible, but consider that insects may come indoors in the soil. Also, the rhizomes need to overwinter dry so they don't rot, yet not so dry that they shrivel and lose moisture. Dahlias are fairly heavy "feeders" and will need good organic soil next year, plus a balanced fertilizer to replace nutrients used up in the potting soil this summer.
University of Maryland Extension's Home and Garden Information Center offers free gardening and pest information. Call 800-342-2507 or send a question to its website at extension.umd.edu/hgic.