Although never fatal, mildew can be unsightly and may lessen flowering and cause leaf drop. Keeping plants well watered and cool appears to be the most important factor in mildew prevention.

Healthy plants  resist mildew. Stressed plants will usually develop some degree of mildew. What are the proper conditions that make them happy, healthy and mildew-free? Grow them in a cool location, preferably in a little shade, and in a humus-rich soil, plus at least 6 hours of sun. Additional tips:

• Do not overcrowd your plants; this will lead to poor air circulation and will create problems with the humidity level around susceptible plants.
• During the winter the fungus survives on plant debris, so it is important to clean up around infected plants.
• Using high nitrogen fertilizers (the first number of three on fertilizer labels) promotes weak, leafy growth; try a balanced fertilizer with low numbers and apply only once in the spring to give perennials a boost for the season.
• Choose disease-resistant cultivars whenever possible.

There are hundreds of Phlox varieties to choose from. You may want a fragrant Phlox, a short or tall one, or historical heirlooms, or the more mildew-resistant varieties. So here they are:

Best mildew resistance: Blue Lagoon, Blushing Shortwood, Bright Eyes, Caspian, Cinderella, David, David’s Lavender, Delta Snow (the very best), Hot September Pink, Jeana (also the very best), John Fanick, Midsummer White, Miss Lingard, Miss Universe, Natascha, Old Cellarhole, Omega, Robert Poore, Rosalinde, Russian Violet, Shortwood, White Admiral, Widar.

Fragrant phlox: Cinderella, David, Ending Blue, Fairy’s Petticoat, Franz Schubert, Katherine, Midsummer White, Mile High Pink, Miss Pepper, Miss Universe, Old Cellarhole, Russian Violet, Starfire, Widar.

Heirloom phlox cultivars--all dating from before 1950: Amethyst (by 1949), Blue Boy (by 1945), Brigadier (1940s), Caroline van den Berg (by 1945), Charles Curtis (c. 1945), Cinderella (by 1949), Europa (1910), Eventide (by 1942), Jules Sandeau (by 1934), Miss Lingard (by 1889),  Newbird (by 1931), Progress (by 1944), Rijnstroom (1910), Rosalinde (1920s), Salmon Beauty (by 1945), Spitfire (by 1940), Widar (by 1931), Wilhelm Kesselring (by 1931).

Shortest and tallest phlox:

Short phlox, 3 feet or under: Anne, Aureole, Blushing Shortwood, Delilah, Fairest One, the Flame Series, Jade, Jr. Dance, Jr. Dream, Jr. Surprise, Little Boy, Little Princess, Miss Lingard,  Natascha, Omega, Red Riding Hood, Shorty White.

Tall phlox, 4-5 feet: Bright Eyes, Cabot Pink, David, David’s Lavender, Delta Snow, D.H. Forbes, Fairy’s Petticoat, Hot September Pink, Midsummer White, Miss Holland, Miss Universe, Mt. Fujiyama, Pink Bud, Salmon Beauty, Sherbert Cocktail, Sir John Falstaff, Spitfire, White Admiral, Widar.

Very tall phlox, 5 feet or more: Caspian, Hesperis, Kirmeslandler, Mile High Pink, Old Cellarhole, Robert Poore, Russian Violet.

For tips on a variety of gardening topics, see our Plant Information Guides.
- Courtesy of NYBG Plant Information Service