Date: Fri, 18 Dec 2009 10:59:51 -0500
From: Al Cooke
Subject: holly berries
There are at least 4 species of holly, both evergreen and deciduous, that are native to Chatham County and others that do well here, especially several Chinese varieties and some hybrids. Despite their extensive use as a foundation plant, Japanese hollies (black berries) are not outstanding selections for heavy wet soils and often are short-lived here due to root rots. The native and underused inkberry holly is often a better choice. All hollies are dioecious, meaning that male and female flowers occur on separate plants. In many cases the female plant will not bear fruit unless there is a male that blooms at the same time and there are insects that visit both plants. In some cases the female is parthenocarpic meaning it can develop seedless fruit without pollination. And the males never bear fruits.
Why a plant fails to bear fruit in some years can be a challenging pursuit. A first question is always maturity. Plants mature at different rates depending on species and growing conditions. A Magnolia seedling may not reach maturity for 10-12 years, a wait that can challenge the patience of gardeners awaiting flowers. For that reason horticulturists “capture” some species in maturity and propagate clones vegetatively (by cuttings) so that plants may bloom in their first year of growth. But I’ve gotten away from hollies. Some years the plants will bloom (small flowers which many observers fail to notice) before the last freeze. In those years the young fruits may be freeze damaged and typically fall before they enlarge. In some years the plant has a very large crop of berries and is spending all its energy to bring them to maturity. After all, the plant is primarily interested in getting its genes into the next generation! In these cases, it may spend so much energy on the berries that it spends none on flowering that year. The flower buds are typically set during late summer about the same time berries are enlarging. If the plant doesn’t set buds in the summer, then there are no flowers the following spring and no fruits the following year. Pecan growers refer to this phenomenon as alternate year bearing. And sometimes with plants like holly, gardeners will shear the plants in late spring removing all the fruits that were set earlier in the spring. And sometimes things like drought will cause a crop of berries to abort.
So there are many possibilities for either berries or no berries. I may have neglected some. But there are at least a few avenues for investigation.
alcooke
Al Cooke
Extension Agent, Horticulture
Chatham County Center
N.C. Cooperative Extension
PO Box 279, Pittsboro, NC 27312
919.542-8202; Fax 919.542.8246
http://www.ces.ncsu.edu/chatham/staff/acooke/home.html