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University
of Rhode Island GreenShare Factsheets
Hollies
Ilex spp.
During the holidays, holly branches add a bright, dramatic
touch to wreaths. Hollies can add that same drama to the landscape.
Hollies (genus Ilex) with their beautiful evergreen foliage
and bright berries make good accent plants, hedges and also add
great winter color. They are fairly easy to grow and have few
pests or other problems. Hollies do have a reputation for slow
growth, but new hybrids have increased the speed of growth; Ilex
meserveae can become a good-size shrub in just a few years.
All members of the Ilex family are not evergreen shrubs.
The American Holly (Ilex opaca) grows to 50 feet. There
are dwarf forms that can be used as low maintenance hedges as
well as deciduous forms such as Ilex verticillata
• For the fullest, most
compact growth and best berry production, hollies need full
sun, although they will tolerate
shade. They thrive in slightly acidic soil with lots of organic
matter. The soil needs to be well-drained, as hollies do not
like overly moist soil. Regular watering, however, is needed
to keep the plants looking their best. Several inches of mulch
will help preserve moisture in the soil.
• A dose of acid-based fertilizer
in late fall will give the plant a good start on the growing
season. Adding a good
layer of compost helps fertilize the plant and adds organic matter
to the soil.
• Hollies respond well to pruning.
Greens can be cut for the holidays without harming the plant.
Holly can be pinched
back to promote branching and new leaf production for a fuller
plant.
• Chlorosis, a yellowing
of the leaves, can be a problem if the soil pH is too high
or if the plant is not
receiving enough nitrogen. If the leaves begin to yellow in the
summer, an application of a 10-5-5 fertilizer should help. If
the problem is persistent, check the pH of the soil.
• Holly foliage can be damaged
by wind and dry conditions, especially if the plant is in an
exposed site. Drying out can
be a significant problem for young plants.
• Insects which can infest Ilex include scales,
bud moths, red mites and leaf miners. Damage inflicted by these
insects is usually minor. A careful spray with an insecticidal
soap should be sufficient to control any insect infestation;
a routine spraying regimen is not recommended.
The English holly, Ilex aquifolium, is
the "typical" holly
plant. I. aquifolium is very sensitive to drying out and
needs to have its roots mulched to keep them moist. There are
several variegated forms which make excellent specimen plants
or backgrounds for a perennial border.
The hybrid 'Nellie R. Stevens' is similar in appearance
to the English holly but has fewer problems. 'Nellie' is a fast-growing
cross between the English and Chinese holly. This cultivar has
excellent dark green foliage and large, red berries and will
grow into a beautiful specimen tree.
The Meserve hollies, commonly referred to as the blue hollies,
are some of the easiest to grow. Very hardy and reliable for
setting berries, they make a dramatic addition to the landscape.
The foliage is very dark green with a blue cast. 'Blue Stallion'
and 'Blue Princess' make an excellent hedge. Other Meserve hybrids
are 'China Boy' and 'China Girl'. The foliage of these hybrids
is a lighter green and has excellent berry production.
The Japanese holly, Ilex crenata, is a good substitute
for boxwood. Very similar in appearance to boxwood, the Japenese
holly is very hardy and grows more quickly than boxwood. The
leaves are evergreen, but not stiff like traditional hollies,
and have a soft gray cast. The berries are blue and not highly
conspicuous. Dwarf varieties such as 'Helleri' will produce a
nicely shaped hedge with little pruning.
Ilex glabra, a native holly, is now being used in
roadside plantings and makes an excellent evergreen hedge. This
holly is extremely hardy--it grows in any soil, in full sun or
partial shade and is pest and disease resistant. The foliage
is persistent during the winter and has a rich blue-green cast. Ilex
glabra's blue berries attract birds.
Deciduous hollies can thrive in the landscape as well. Winterberry (Ilex
verticillata) is a native deciduous holly. The summer foliage
of winterberry is not as dramatic as the evergreen, but the
berries that persist during the winter are very attractive.
'Sparkleberry' is an attractive hybrid of winterberry with
sparkling red berries highlighted in the winter landscape.
While the dwarf form 'Sprite' is a much smaller bush, its large
red berries cover the bush in the winter. Both of these hybrid
forms are compact and work well in smaller yards.
• Hollies are dioecious, having
separate male and female plants. If you want berries you need
to plant one male
for every 5-10 females.
• Your plants also need to be
compatible. It is important to choose the same variety of male
and female holly so that they
bloom at the same time, which allows for the exchange of pollen.
• Don't over fertilize! Flowering
and therefore berry production is inhibited, if the nitrogen
level in the soil is
too high.
Note: Holly leaves and berries are toxic and should not
be ingested
By Cheryl Cadwell, URI Master
Gardener
Pesticides
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
For more
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
University
of Rhode Island Cooperative Extension provides equal program
opportunities.
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