Many gardeners choose ornamental plants for the landscape because of their colorful fruit. Red holly, nandina and orange pyracantha berries are just a few of the ornamental fruits that bring color to the garden.
An added bonus is these plants attract birds. However, many times homeowners are disappointed because a plant they thought would produce berries winds up not producing anything. And sadly, some waste years waiting. Gardeners need to know the sexual characteristics of the plant they want to grow.
Many plants have perfect flowers. Roses and viburnums are examples. This means that each individual flower has both male and female parts – stamens, which produce pollen, and a pistil, which contains the ovary that produces the seed and hence the fruit. This makes self-pollination possible.
Monoecious plants are also capable of self-pollination. Unlike perfect flowered plants, monoecious plants have two types of flowers – male (staminate) and female (pistillate). Both types occur on the same plant. Birches and pines are examples of monoecious plants. In either perfect flowered plants or monoecious plants, pollen is easily carried to the stigma of the same flower or of the female flower of the same plants by insects, birds or wind.
In dioecious plants, pollination is not as easy. Each plant has only male or female flowers, so if a particular plant is the only one of its species in an area, pollination is impossible and there will be no fruit. Hollies are examples of dioecious plants. To ensure a good fruit set on these plants, male and female shrubs or trees must be grown within a reasonable distance of each other.
Identification of sexes in dioecious plants is not difficult, though sometimes it may require more than the naked eye to see the tiny flower parts involved. Male flowers lack stigmas or have undeveloped stigmas, and will have stamens. Obviously, a plant with fruit will be female, but a fruitless plant is not necessarily male. The plant may be fruitless because it lacks pollen or environmental conditions were not suitable for pollination.
Occasionally, the lack of fruit is desired. Fleshy, fruit-like ginkgo seeds have an objectionable odor and mulberry fruit can litter the ground. In such cases, it may be very useful to plant only male trees, as a female tree could receive pollen from neighboring sources.
It might be nice if sweetgum trees were dioecious, because if they were, maybe some would not produce the sticky balls. Unfortunately, they are monoecious, so they will always produce balls every year.
Research the sexual characteristics of the plants you want to produce berries so you won’t wind up disappointed after you plant them.
WAIT TO PRUNE FLORIST HYDRANGEAS: I continue to be asked about cutting back hydrangeas. As those of you know who grow them, they are not the best looking thing in the landscape now because they have lost their leaves after a few heavy frosts and only bare stems remain. But unless it is just a snip here and there, you need to wait until summer to prune them.
There is a rule of thumb we go by on pruning flowering trees and shrubs. If they are early spring flowering, which is before about the first of May, prune them after they finish blooming because they set their flower buds on the previous year’s growth. Good examples are dogwoods, forsythia, and azaleas.
If the plant is summer flowering, or blooming after the first of May, prune it during late winter or early spring because it sets its flower buds on the new growth. Examples are crape myrtles, altheas and roses.
As you know, there are always exceptions to a rule and hydrangeas fall into this category. Hydrangeas produce flower buds in the fall, so pruning during winter or early spring will remove potential flowers. Wait until the main flush of growth is over, usually sometime during June, then prune them. Wait until the flower heads begin to fade, then cut back the larger branches. This encourages new growth that produces next year’s flowers. Try to be done with your pruning by late July.