I want to be sure to get berries on my (female) Ilex crenata convexa
so went looking for male Ilex crenata cultivars. It is not that easy.
So my question is: will Ilex species pollenize each other? For example, I have
a big male holly tree (Ilex aquifolium) close by, will that pollinate the
female Ilex crenata convexa?
The best berry production will come from planting a male and female of the
same species, but you can sometimes get away with using a different
species as long as both the male and the female plants are the same type
of Ilex (that is, both deciduous or both evergreen) with the same
(potential) color berries (red or black-berried species). Also, you want
two plants which flower at the same time.
Ilex crenata potentially produces black fruit. Ilex aquifolium produces
red fruit, so this would not be a good match. I. aquifolium is also
considered an invasive species in our area.
This link to a page from Clemson University Extension, describes various species and cultivars of Ilex. Ilex glabra is another species which produces black fruit.
There are some male cultivars of Ilex crenata, such as ‘Green Dragon,’
‘Hoogedorn,’ ‘Nigra,’ ‘Rotundifolia,’ and ‘Beehive.’
According to the website of a local gardener, there are other hollies
which will cross-pollinate with Ilex crenata, but she does not specify
which ones.
You are in good company in your quest for male Ilex crenata
cultivars–a local (Seattle) garden writer had a very similar question
recently. I hope you are able to get berries on your plant–you could try
waiting to see if perhaps you do get fruit (if there are other hollies in
the neighborhood), and then mail-order a male specimen or ask your
favorite local nursery if they sell any of the varieties mentioned above.