Most people are familiar with holly and its beautiful red berries. A common adornment associated with the holidays, holly is actually a great choice for gardens year round. The dark green foliage and bright pops of colorful berries add interest to garden spaces and work well as foundation plantings. Incredibly hardy, holly plants have an extensive, deep root system that allows them to establish themselves easily and compete well for nutrients and water.
Even the hardiest plants can be affected by factors that prevent them from flowering and bearing berries. These are the seven most common reasons holly plants might not have their traditional red bursts of color.
1. Plants are dioecious
A big misconception is that all holly bushes have berries. Holly plants are dioecious, meaning there are separate male and female plants. Only female plants flower and, if fertilized, produce berries. To make sure your female plants produce berries, plant a male bush within 200 feet.
2. Some varieties don't form berries
Even more complicated is that, although most holly varieties form berries, certain ones don't. Carissa dwarf and Stoke's dwarf produce only male plants — no females at all.
To produce berries, the shrubs must first form flowers. If plants are pruned too early or too severely and flower buds are removed, the shrub won't yield berries that year. Holly berries grow on 2-year-old growth, so pruning in the summer or fall may cut back growth that would flower the following year.
4. Juvenile plants
Holly plants typically need a few years of good, solid growth before they begin flowering and producing berries. Juvenile plants will not be mature enough to flower until they are 3 to 5 years old.
5. Too much shade
Hollies are shade-tolerant and will take over as undergrowth in many forests. However, when the plants don't receive much sunlight, they won't flower as heavily, reducing berry production. They won't produce any at all if the area is shaded enough.
6. Dry weather
Plants have natural defense mechanisms to help them survive adverse conditions. For example, they might drop their leaves and flowers to conserve resources. Prolonged dry weather is a danger to plants and will cause them to react accordingly. And no flowers means no berries.
7. Late frost
A late-season frost can wreak havoc on holly plants. If plants have already flowered, a hard frost will kill the flowers that would have become berries later on.