Q: How often do you recommend fertilizing?
A: I don't fertilize my perennial beds because I don't want them to get tall and floppy. For container plants, though, I feed constantly because I want plants worthy of a magazine cover. Label directions say to feed every seven to 10 days. That's not enough. I found this out when I was working on a book and needed to photograph my containers. A hailstorm smashed everything, but by feeding more often than suggested, the plants miraculously came back within three weeks.
So I recommend feeding container plants every four or five days. Early in the season, switch back and forth between a nitrogen fertilizer and one that's lower in nitrogen but higher in phosphorus and potassium to boost blooms—except for plants you're growing for their foliage. Once the plants are in flower-production mode, by mid-July, use just the flower booster, assuming the plants are the size you want. Never fertilize when the soil is dry; it can burn some plants.