Q: I think I need a pollinator for my winterberry, since it’s by itself and has no berries. How do I know which variety to get?
A: It can depend on which female variety you’re growing. Winterberry holly (Ilex verticillata) produces male and female flowers on separate plants. Female plants produce fruit (berries) once they are pollinated by insects (mainly bees); male plants do not fruit. One male shrub produces enough pollen to fertilize several female winterberries, so they don’t need to be planted in a one-to-one ratio.
The flowering period for winterberry lasts a few weeks, though blooms are not open and fertile for that entire time. During that window, some individual shrubs may open blooms early and others late, due in part to genetic influences. Early-blooming female winterberries should be partnered with a male that also flowers on the early side. An early-blooming female and a late-blooming male won’t be a great match, and may not have enough flower overlap to successfully pollinate.
Cultivars have fairly consistent, known traits, which include the sex of the flowers, how early or late the plant blooms during its flowering season, and the mature plant size. For female cultivars, traits also include the berry color, size, and abundance. You can select compatible pairings based on information provided by the nursery or plant catalog/breeder. Tags or signage providing information about female winterberry cultivars usually mention which male cultivars make the best pollinator choices. Keep in mind that such notes aren’t always exhaustive; they might list one or two male cultivars (especially if they’re part of the same brand), but they aren’t necessarily the only males that will be a suitable pollen source.
If you’re growing the straight species (that is, not a cultivar), then it will be potluck as to what relative bloom season (early, mid, or late) any individual plant will have. In that case, if you have room, plant several individuals so hopefully some of the males and some of the females make good matches. Young winterberries that haven’t reached flowering age yet can’t be sexed, so the only way to help ensure that at least some fruiting happens is by planting several shrubs, whether in a cluster or scattered around the yard.
Sometimes you don’t know what variety you’re growing. In that case, it just may take some trial-and-error guesswork. (If the shrub is male, it won’t ever produce berries, though still is very valuable to pollinators.) You could try to find a male that blooms mid-season, or one each of an early-blooming and late-blooming male cultivar. Or, choose a male and female pairing to plant elsewhere in the garden and the original plant will hopefully either also produce berries (if female) or help to pollinate the new female shrub.
Q: I’m creating a sign to post at the edge of my yard about why I’m leaving leaf litter in place for wildlife. Are insects the only animals that use fallen leaves during winter?
A: Although insects are the focus of most “leave the leaves” messaging, lots of other animals can seek shelter there too, or even eat the leaves at some point as decomposers and nutrient recyclers. Reptiles and amphibians, spiders, other arthropods (springtails, roly-polies, millipedes, etc.), and small mammals can shelter within leaf piles and leaf mulch. Some ground-feeding birds will forage in fallen leaves, kicking them around with great gusto to find morsels to eat.
You may be surprised to learn that leaf litter also benefits the Eastern red bat. Found throughout the state, this native species mainly takes shelter in trees, but may shelter in leaf litter instead. Given their secretive nature and camouflaging caramel color, we’d never know they were there.
This Halloween, as we find ourselves surrounded by bat and spider motifs, keep in mind how our gardens and home landscapes can support these important elements of biodiversity and healthy ecosystems. Both consume species that we consider pests, and spiders are a nutritious source of food for birds (especially nestlings).
University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click “Ask Extension” to send questions and photos.