By Kerry Mendez
Q: I’ve noticed white fuzzy stuff on the leaves of my garden phlox. What is this, will it kill my plant and how can I get rid of it?
A: It sounds like your phlox has a case of powdery mildew, a fungal disease that is common to phlox, bee balm, heliopsis, and lilacs. Powdery mildew is an unwelcome, although frequent, visitor to many summer gardens; it is unsightly to look at, but it rarely kills plants. Powdery mildew is a fungus that appears on a plant’s leaves as a result of spores in the soil that are carried to the leaf and stem surfaces via splashing water or breezes. The problem is exacerbated in gardens with poor air circulation and watering techniques. You can increase airflow by weeding and dividing overgrown plants. The best time to water perennial gardens is in the morning so that the leaves are dry by nightfall. How to treat the disease? First, strip off all infected leaves and get rid of them. Do not put them in your compost pile. Then spray the remaining foliage with an organic solution consisting of one teaspoon of baking soda and a few drops of liquid dish detergent mixed in a quart of water. Use a mister bottle to spray both upper and lower leaf surfaces. This solution changes the pH of the leaf surface reducing spore germination. Since powdery mildew spreads rapidly, it’s best to get on top of the problem early —or better yet—be proactive and start spraying leaves every two weeks, starting in May, before you see any sign of mildew. Finally, when purchasing new plants, look for mildew resistant varieties of these susceptible perennials.
Q: I’ve heard my friend talking about re-blooming daylilies. How are they different from other daylilies and where can I buy them?
A: Re-blooming daylilies are the rage now. They are also commonly referred to as twice blooming or repeat blooming daylilies. Most daylilies only bloom for three to four weeks. Re-bloomers persevere for six weeks or longer. The one that many people are familiar with is Stella De Oro; a golden yellow daylily that gets around 18” tall. In my opinion, this has been greatly overused. There are so many other re-bloomers on the market these days. Some of my favorites are Pardon Me (red, 18”); Happy Returns (yellow, 18”); Strawberry Candy (pink, 26”); Fairy Tale Pink (light pink; 24”); Little Grapette (purple, 12”); Bama Music (pink, 28”); and Little Business (red, 18”). To keep repeat bloomers flowering their best, cut off each long stem (scape) right to the base of the foliage after all the flowers on it have bloomed. This will encourage the plant to send up additional scapes with more buds. If you do not do this, the plant will put its energy into producing seed pods (those swollen knobby looking things that trick you into thinking they are buds). You can also treat your daylilies to a time released fertilizer such as Plant-Tone that will slowly fertilize them over a three to four month period. Repeat blooming daylilies are usually more expensive than other daylilies, but are well worth the expense with their glorious extended blooming season.
Q: My ‘Nikko Blue’ hydrangea stopped blooming a few years ago. Now it is just a big, leafy bush. Why isn’t it flowering?
A: There could be a number of reasons for your flowerless hydrangea. To bloom best, ‘Nikko Blue’, one of the mophead, big leaf hydrangeas (macrophylla) needs sun to part sun. Many times people have it in too shady a spot where it only receives a couple of hours of direct sun. Sometimes the reason is due to using the wrong fertilizer, namely one that contains too much nitrogen (the first of the three numbers on the fertilizer bag). Excessive nitrogen will encourage leaves at the expense of flowers. If your hydrangea is surrounded by, or alongside the lawn, your lawn fertilizer (high in nitrogen) could be leaching to it and may be part of the problem. Fertilize your hydrangeas with a balanced fertilizer such as 10-10-10. Proper pruning is also important for good flowering. The best time to prune is either right after they finish flowering or in early spring. If you prune in the spring (April), prune out dead wood and cut branches that are greening up back to a pair of fat green buds. Most mopheads set their flower buds on the prior year’s wood. This makes them susceptible to bud freeze over our long, cold Northeastern winters, resulting in few, if any, flowers the following year. ‘Endless Summer’ is a recent introduction that blooms on both old and new wood and is hardy to zone 4 (the majority of mophead hydrangeas are only hardy to zone 5). Because ‘Endless Summer’ blooms on new wood, the danger of bud freeze is greatly reduced. ‘Endless Summer’ will flower either pink or blue depending on if you have sweet soil (raising the pH with lime) or acid soil (lowering the pH with sulfur).
Q: I have a flower garden that is located under some trees and I am having a hard time getting plants to grow there. Can you recommend perennials that will do well in dry shade?
A: Dry shade is a tough gardening assignment, especially if the trees creating the shade are maples. You need to use perennials that can compete with tree roots for the limited amount of water and nutrients. Lamiums are a good choice. They are a low growing, spring blooming perennial with pretty pink or white flowers and showy leaves. My favorites are the silver-leaved varieties such as ‘Pink Pewter’ or ‘White Nancy’. Another top pick is epimediums. These make a super groundcover and have pink, yellow or white flowers in the spring. Their heart-shaped leaves have a pretty burgundy tinge to them. Good old hostas can also rise to the challenge of dry shade. They can range in size from only a few inches tall to over 3 feet. There are so many exotically beautiful hostas on the market today that there is no reason to feel limited to the more common green and white ones. Tiarellas (foam flowers) are another winner. Flower colors are creamy white or pink. But it is the foliage that is their main attraction, with darker markings on the leaves becoming more pronounced after the flowers fade in early summer. Finally, when planting these drought tolerant shade lovers it is important to give them regular waterings during their first season as they get established and to use a nutrient-rich mulch that will keep weed competition down and reduce water loss to evaporation.
Kerry Mendez is the owner of Perennially Yours, a local business that specializes in low-maintenance gardening classes, design and consulting services. To learn more about Perennially Yours please visit www.pyours.com.