Modern daylilies exhibit three types of
foliage habits - dormant, semi-evergreen, and evergreen. These three
habits are not always well defined, because some cultivars seem to fall somewhere in
between. The hardiness of a cultivar in northeast Wisconsin is often
related to it's foliage habit. The following is a perspective on the foliage types and
their general characteristics and behaviors including hardiness...
Dormant daylilies have foliage that begins
growth when temperatures are warm enough to support healthy plant progress
in cool climates. They also stop growth late in the season when cool
temperatures and a shorter day length can no longer support their increase. "Dormants" appear to require a winter down
time to prosper. Just prior to winter, resting buds are set in the
crown of the plant and leaves die down. Resting buds are 'bullet
shaped' in appearance and are found just below the soil surface, where
they remain until warmer spring temperature trigger their growth.
Due to their compact structure, resting buds are well protected from ice,
dehydration and other environmental factors experienced during the winter
months. Dormant daylilies are well suited for Wisconsin and
poorly equipped for Florida and similar warm climes. Dormants generally lose vigor
in areas that do not experience freezing temperatures. Spring
foliage on dormants in northern regions is generally more robust and
healthier than
semi-evergreens and evergreen cultivars. Flowering and bud counts
also tend to be better on dormant plants in Wisconsin, but the opposite is
true in
warm climates.
One
last item about dormants deserves consideration...photoperiod dormants! A number of
dormant cultivars have been coming out of southern hybridizing programs
recently which do not prosper in Wisconsin. Many of these plants appear
dormant, but are not resilient to extreme cold. Day length in these
cultivars causes dormancy in both the north and south, but the hardiness
factor has been removed.
How
can a consumer tell if a semi-evergreen or an evergreen is hardy in
north? If you are adept at studying hybridizing
pedigrees, you may be able to determine an evergreen's chances in
the cold by looking at its parents' hardiness (an educated guess).
Most consumers wait for someone to test the cultivar in a cold
climate before making a purchasing decision. A daylily
society such as the Bay Area Daylily Buds and its members can be of
great assistance by providing information concerning cultivar
hardiness.
Evergreen daylilies are best suited to warm
climates like that of Florida. These plants exhibit continuous growth, even
during cold weather. Evergreen foliage can sometimes be seen growing beneath
snow, but unfortunately it typically freezes and turns to mush. Evergreens
generally weaken themselves during winter months in
cold climates by continually growing without the benefit of proper day-length and temperatures. Growing and losing foliage to cold
temperatures is not a beneficial tactic for Wisconsin. One might
think that no evergreen daylilies would do well in Wisconsin, but some
actually prosper! For instance "Lunar Max," an
evergreen, grows and blooms nicely despite negative 20 F
temperatures. It's foliage often looks mushy in the spring and the
plant grows
some rather yellow leaves for a couple of weeks, but later this cultivar gathers itself
for a great July bloom. Evergreens are the plant of
choice in the south and many beautiful flowers are born on this type of
plant. Florida hybridizers, as well most other hybrizders in
the U.S., produce many new evergreen daylily cultivars every
year, a few may grow in Wisconsin, most will freeze out or rot in the
spring.
Apparently not just temperature affects the
hardiness of a particular cultivar, but a combination of conditions during
winter months. Exposure, moisture, frost heaving, soils, and
establishment of the plant before cold weather all appear to play a
role. The consumer should also be aware that many growers and sellers grow daylilies in
greenhouses, and, of course, this will not give the buyer an accurate
account of hardiness. Plants out of Florida and other southern
states are
a gamble, but sometimes the flowers are so gorgeous they are worth the
unexpected. Mulching these plants through their first winter often
increases the chance for survival.
Semi-evergreen daylilies are creatures
whose intermediate foliage behavior is not adequately described as
simply dormant or evergreen. Most of the daylily cultivars
registered within the last few years have been given the
semi-evergreen designation by their hybridizers. Many of these
cultivars behave as evergreen daylilies in our Wisconsin gardens.
Semi-Evergreen
cultivars, in theory, should not go completely dormant, but
will slow or stop growth during very cold weather. If you ask five different daylily growers what a
semi-evergreen looks like, you will
probably get five different answers. For northern gardeners, the
practical point about semi-evergreens is that while some cultivars
that are registered as semi-evergreen will prosper in Wisconsin,
many other cultivars that are registered semi-evergreen are as
intolerant in the north as are most evergreens.
In summation, foliage habit does not
completely indicate a plant's hardiness or it's performance level.
Dormants are best suited to the typical Wisconsin climate,
but some semi-evergreens and evergreens are acceptably hardy in our gardens.
