Lily of the Valley launches a hostile takeover
What to do this week: Take time to smell the peonies and roses. Finish planting cold-sensitive flowers like impatiens and dahlia, as well as warm-weather vegetables like tomatoes, beans, melons, squash, corn, peppers, squash, cucumbers and eggplant. Consider using pots of culinary herbs such as basil, rosemary, chives, oregano, parsley, sage or thyme in a sunny outdoor spot near the kitchen door. It’s easy and gives great bang for your buck if you cook, and who doesn’t these days? When planting container gardens, remember that the larger the pot, the less often you should water it. Consider purchasing a “self-watering” outdoor container.
s. I have a rock garden next to a small pond with perennials like bleeding heart. In my haste to get more coverage, I planted a lily of the valley. It’s taking over and growing into ginger with waxy leaves which I love. Will my ginger take over? Do I take it out?
British Petroleum, reading
a. Sooner or later, most gardeners learn the sad lesson that even beautiful plants can be very tough. Although lily of the valley has a delicate appearance, surprisingly, it is a true garden plant that does not play well with others. So, yes, pull out all those stubborn little creeping root stems. You may have to dig up plants that have already infiltrated like your European ginger and either untangle the roots or dispose of the entire mess. And if you give any lily of the valley away, warn your recipient to isolate it in a shady spot where they can safely harvest the beloved scented white bells in May without them overwhelming their other plants. Many perennials once welcomed as low-maintenance ground covers have turned into relentless invasives. Avoid planting periwinkle (Vinca minor), ribbon grass (Phalaris arundinacea), wintercreeper (Euonymus fortunei), English ivy (Hedera helix), or any plant described as a “vigorous spreader,” which is nursery code for an “unruly aggressor.” “. Choose the perennials you add to your garden beds filled with horticultural treasures as carefully as you choose your children’s playmates. Prevent bullies!
s. I have a gorgeous bearded irise in a rock garden. The upper level has stopped blooming. They are in full sun with healthy foliage, and I added compost. What happened?
Republika Srpska, Sudbury
a. Bearded iris is actually a great perennial for full sun. Thanks to dedicated breeders, they come in many sizes and gorgeous color combinations, but the flowers stop blooming when the roots become crowded. So, there comes a summer day about every five years when you need to grab a large garden fork and dig the shallow roots of the iris out of the ground. Cut or break them apart, leaving about three fans of leaves attached to each piece. Replenish their bed by digging in compost before replanting rhizomes divided horizontally and barely covering them with soil. Water them deeply to stabilize the soil (without trampling), then cut the leaves by two-thirds. You can give remaining plants to other gardeners or exchange varieties with them to build your collection. If you really want to explore the tempting world of iris, visit the excellent Massachusetts Iris Society at massirises.org for local resources and events.
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