Fresh Flora

Cool Down a Hot Garden with Blue Plants

by Virginia Hayes

Sophisticated garden designers know it isn’t just about the
pretty posies when creating exciting landscapes. Flowers are nice,
sure, but they really aren’t even necessary to make a garden hum
with energy. Those in the know rely on plant form and foliage color
as much as on the floral display available from a particular
selection. While we usually think of plants as “green,” they often
come in other colors, too. Leaves are green because the major
photosynthetic pigments are green, but there are lots of other
factors that contribute to the color we perceive when looking at a
plant. Secondary pigments may add red — from pink to darkest
burgundy — and shades of yellow. The absence of pigments creates
white or ivory, but one of the most striking tints to be found in
foliage may be blue.

The color blue, when displayed by leaves and stems, is designed
by nature to cool down a hot scene. This shade is quite literally
about shade. Plants from climates with lots of intense sunshine are
the most likely to sport this cool hue. In order to deflect some of
that sunlight, their leaves are clothed in reflective coverings
that mask the natural green pigments, giving the plant a blue or
silvery tint. These protective shields come in many forms, but most
are some type of wax that covers the epidermis of the leaf. It’s
easy to demonstrate this phenomenon by rubbing the leaf. Without
too much effort, you can remove most of that wax, revealing the
green.

The majority of plants sporting this adaptation are succulents;
agaves and aloes are probably among the most familiar of this
group. Not all members of these genera are blue, but some of the
more common ones are: Agave franzosinii, A. attenuata, A.
americana, A. attenuate ‘Boutin’s Blue’ (formerly known as ‘Nova’),
A. parry and A. gypsophila, Aloe arborescens, and A. plicatilis.
Other succulents that can provide contrast to a green garden are
Senecio mandraliscae and its close relative S. serpens (both
sometimes known by the common name blue chalk sticks), many species
and cultivars of Echeveria and Sedum sieboldii, and S.
spathulifolium. There are bluish yuccas, too, such as Yucca rigida
and Y. baccata.

Another group of plants that have similar adaptations are the
cycads, and the blue ones are particularly popular. Encephalartos
horridus, E. lehmanii, and E. trispinosus are becoming more
well-known, although there are blue forms of other species as well
including Dioon edule. Blue palms include the Mexican blue palm
(Brahea armata), the jelly palm (Butia capitata), and the stunning
Bismarkia nobilis. There are grasses with a blue hue — blue
lovegrass (Eragrostis chloromelas), blue oat grass (Helichtotrichon
sempervirens), and blue fescue (Festuca ovina), to name a few.
Dichondra argentea is definitely silvery and works well as a
groundcover or in a hanging basket. Conifers like Cedrus atlantica
‘Glauca,’ juniper (several in a variety of sizes), and Colorado
spruce (Picea pungens) also have blue-ish foliage and there are a
number of eucalyptus species that can also provide interest in the
upper strata of the landscape.

Blue or silver plants add instant drama to the garden. Use them
singly as a foil against masses of green or as a focal point to
direct the viewer’s attention. For a bold statement, use multiples
of the same plant either in the background or as a border. Since
most of these plants are perennials, they can become valuable
components in the backbone of garden. Plant seasonal annuals next
to them to either play off their cool hue (blue lobelia between the
clumps of blue fescue) or pair them up with hot colors for contrast
(scarlet nasturtiums clambering through the agaves, for example).
Most are also adaptable to container gardening so you can also
arrange them in similar compositions in pots.

One of the other things blue plants can do for your garden is to
lighten up an area. While most plants with blue foliage will
require full sun, their bright, reflective surfaces bring even more
light into play. This can be particularly true after the sun goes
down. By the light of the moon, these plants take on a ghostly
presence and seem to almost glow. The effect is amplified even more
after the dew has settled on them.

Whether you use blue plants to dramatic effect or you just like
the way they look, they are sure to elicit admiration from visitors
to your garden.

Virginia Hayes, curator of Ganna Walska Lotusland, will
answer your gardening questions. Address them to Gardens, The
Independent, 122 W. Figueroa St., S.B., CA 93101. Send email to
vahayes@lotusland.org.