Issues → October 2006 → Home & Garden →
Our Backyard: Mums, Fertilizer, Bittersweet
by R. Wayne Mezitt
Every fall I buy beautiful hardy mums, but they don't seem to survive the winter in my landscape. What am I doing wrong? -- D.B., Cambridge, MA
The chrysanthemums we see everywhere commonly called "hardy mums" are really not designed to survive our challenging New England winter climate -- these are seasonal beauties bred to be enjoyed for the weeks they are in flower but then discarded. Because they are grown in such abundance every year, these chrysanthemums are always inexpensive and a fine decorating bargain.
If you want fall-color plants that thrive in your garden year after year, try planting climate-tolerant cultivars like September-flowering 'Clara Curtis' and 'Mary Stoker'. The "Korean mums" like 'Sheffield', 'Venus', and 'Mei-kyo' produce their flowers even later, often well into October. These winter-hardy types are available at many local garden centers that understand the results customers want, but they are usually not at the "box stores." When you include them in your garden, you'll be rewarded with reliable late-season blooms that look spectacular for weeks in your landscape and are also fine as a cut flower for indoor arrangements.
When to Fertilize?
The flowering shrubs in our landscape don't give us much bloom in our sandy soil, even though we maintain sufficient moisture. Should I use fertilizer? When is the best time? -- K.F., Manchester, NH
Early autumn in New England is generally considered an ideal time to apply fertilizer to landscape trees and shrubs. This is the season when colder temperatures and shorter days slow top growth, but warm soil continues to enable roots to grow. Fertilizer taken up by active root systems builds strength to support next year's flowers, fruit, and top growth.
It's best to choose a high-organic fertilizer. Fertilizers with a strong organic content cost a bit more than inorganic types, but they produce superior results because their nutrients are absorbed by roots systems more gradually. During fall, it is best to use a lower nitrogen formulation with a higher middle number (like 5-10-5, which signifies five parts nitrogen, 10 parts phosphate, and five parts potash). Phosphorus encourages strong root growth, which helps improve flower bud set. A high-nitrogen type may encourage excessive top growth that could be damaged by upcoming colder temperatures. Consult with the experts at your local garden center for recommendations about the best formulations to suit your specific conditions.
Bittersweet is Invasive
Last spring I sent away for three bittersweet plants and received one male and two female plants. These grew high with great leaves, but no berries. What went wrong? -- D.C., Pascoag, RI
First of all, as pretty as their berries are, Oriental bittersweet (Celastrus orbiculatus) is widely considered one of the most threatening invasive plants in New England. Like the kudzu vines that dominate southeastern natural areas, this is the vine we see throughout this region, choking out large trees and causing major damage to natural areas. This species should not be grown in your landscape. Your most responsible action would be to remove your plants before they produce berries, which birds can spread into nearby woods. This is one situation when plastic replications of the plant are preferred to the authentic.
To answer your basic question, "di-oecious" plants, whose male and female flowers occur on separate plants, need to become mature before their female flowers set berries. Hollies (Ilex), bayberry (Myrica), and ginkgo are other examples of plants whose sexes are separate. If you want berries, it is wise to purchase cultivars already identified as female, and often a male pollinator is needed. Should you buy seedlings, you won't know whether you have one that produces berries until it is old enough to flower. Also, when lush growth occurs in high-fertility conditions, many plants will tend to produce leafy growth and fewer flowers and berries. A measure of neglect often encourages better flowering and berry production.
R. Wayne Mezitt is the chairman of Weston Nurseries in Hopkinton, Massachusetts.
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