Ask Mr. Smarty Plants

The native North American members of the genus Ilex (holly) that will grow in the Baltimore area are Ilex decidua (possumhaw), Ilex opaca (American holly), and Ilex verticillata (common winterberry). None of those seemed to be the "Red Holly" you were referring to, but we discovered that there a number of cultivars that have been hybridized from the native hollies that have come to be called red hollies. Here is an article from the Mississippi State Office of Agricultural Communication on Red Holly. When you have a hybridized plant, that makes it a little difficult to determine what its normal growing habit would be, so we really don't know why your hollies are not growing as you expected. We can tell you, however, that it has nothing to do with the gender of the plants. The gender of the plants comes into play when you are seeking to have berries on your hollies. Only the females produce berries, and there will be no or very few berries if there is not a male pollinator in the area. The standard wisdom on that is that there should be one male plant (of the appropriate flowering time) in close proximity to three to five female plants, to ensure good pollination and fruit set.

But to get back to your original question, why are your hollies not growing? Since they are no doubt hybrids of a native Ilex, cultural requirements should not be that different. If you will follow the plant links above to the descriptive webpages from our Native Plant Database, you will learn that the holly is a very slow-growing plant. They also prefer moist, well-drained soils, and are tolerant of shade. It looks like the prescription is for patience. If you don't see any obvious indications of insect or disease problems, it's likely that the hollies are just taking their sweet time getting adjusted to the conditions in your garden, and will grow when they're ready.

Ilex decidua

Ilex opaca

Ilex verticillata