The problem we have determining the sexes of our hollies goes way beyond the genus Ilex. (cf Holly Aird; Holly Johnson.)
I can legitimately use sex as an introduction to the holly. If you think it’s just a headline-grabber, read on and I will justify.
So many people come to me with the question, “Why does my holly never produce berries?” And the answer is sex. There are male hollies and female hollies. Male hollies produce flowers with pollen, with the potential to fertilise female hollies. (Sorry if I’m being too graphic. Gets a bit close to the bone sometimes, this gardening/nature thing.) Female hollies also produce flowers, with the potential to be fertilised by the pollen from male hollies. You know what’s coming next, don’t you?
If you want berries, you need two hollies, a male and a female, and preferably a few obliging insects to do the dirty deed. But as we all know, insects cover a lot of ground. Like, they will cover the ground between you and your neighbour. So if you have a town garden, the chances are someone else’s holly will fertilise yours. If it’s female. Otherwise you will always be the provider.
Simple so far? Now it gets better. How do you know if your holly is male or female? With the common holly (Ilex aquifolium), you don’t. Botanists with microscopes and cutting edge technology struggle. Until the plant is old enough to bear flowers and/or fruits. But that’s a bit late to be finding out. If you want to go for the common holly – which I strongly recommend because it’s native, and therefore of much more use to numerous wee beasties – buy half a dozen or so. C’mon, they’re not that expensive (and if they are you’re shopping at the wrong place!), and if you plant several together, by the law of averages you’ll get a mix of sexes.
If you want to be sure, though, you can buy named variegated varieties. BUT – if I’ve confused you so far, prepare to be bamboozled. A reliable female holly is the variety “Golden King”. A reliable male holly is the variety “Silver Queen”. Just don’t ask, okay? Trust, accept.
But help is at hand. For we have on the market a hermaphrodite (and not in any way genetically modified, I assure you). If you have room for only one holly, look in your Garden Centre for Ilex aquifolium Pyramidalis. If you’ve read my earlier piece on Latin names, it will come as no surprise that this is an upright pyramid-shaped shrub, and in my experience it bears berries very early in life, even when it’s still in the pot on the Garden Centre shelf. It needs no pollinator. It does the business by itself.
PS Before anyone else corrects me, let me correct myself. I’ve just checked my RHS plant bible, and it’s not a hermaphrodite at all. It is a female. But self-fertile. This worries me – it could catch on. Please don’t tell the Dolly-the-sheep doctor.