sun. Prune the top and sides twice a year for formal effect. Give
winter protection with evergreen boughs.
PROPAGATION. Seeds (good but slow), division, cuttings.
SPECIAL USES. Beds, edging, rock gardens, miniature hedges, foundations.
=Thuja= _Pinaceae_ Arborvitae
Certain species of the “tree of life” are majestic monsters. But there
are a number of shrubby varieties of delicate value in small plantings.
All have characteristic scale-like leaves arranged along fan-shaped
branches, making fluffy sprays. But shapes vary from balls to pyramids.
Foliage may be light, or blue-green, or even golden. Smaller forms are:
_occidentalis_--This species has two small varieties,
compacta (slow-growing, dense pyramid) and ellwangeriana (a low
round mound-shape).
_minima_--A very small and a slow-growing ball.
_pumila_--‘Little Gem’--Dense-leaved and globe-shaped.
_pygmaea_--A two-foot globe or ball.
CARE. Cool, moist location. Rich soil and leaf mold. Either full sun or
half shade. City soot harmful.
PROPAGATION. Same as for conifers.
SPECIAL USES. Foundation planting, rock gardens, tubs and other
containers, specimens.
=Tsuga canadensis= _Pinaceae_ Hemlock
This graceful evergreen conifer has slender horizontal branches with
small leaves and small cones. Not all nurseries have it in its few
dwarf forms. Best known of these small varieties are the conical
compacta, and the completely prostrate, creeping prostrata.
CARE. Slightly acid soil, organic fertilizer, shade-tolerant, hardy
(but protect from cold winds), can be pruned.
PROPAGATION. Seeds (stratified), cuttings.
SPECIAL USES. Foundation planting, hedges, specimens, rock gardens,
bonsai.
=Viburnum= _Caprifoliaceae_ Snowball, European Cranberry Bush
An ornamental shrub. Most varieties are deciduous, and are valued for
their heavy flower clusters, fragrance, autumnal color, and attractive
fruit. Sizes and colors of flowers vary.
_carlesi_--Korean snowball--Fragrant pink buds that open as
white flowers about the same time the foliage appears.
_davidi_--About three feet tall with handsome crinkled
leaves sharply creased at the veins. Small clusters of white
flowers in June; blue fruit in the fall.
_nanum_--A real dwarf popular for low hedges and rock
gardens. It is strictly ornamental, with no flowers or fruit.
CARE. Any soil is acceptable. Moisture required. Hardy.
PROPAGATION. Stratified seeds, cuttings (hardwood or green wood under
glass), layers, grafting.
SPECIAL USES. Rock gardens, hedges, specimens.
_CHAPTER 15_
MINIATURE PERENNIALS
AND ROCK PLANTS
Our odd piece of Connecticut countryside is shaped rather like the
blade of a paring knife. We cleared the point to make a wild-flower
garden. At the blunt end, on one side, a tree-lined bank dips down
to the road. On the other, there is an old, low rock wall that’s not
particularly beautiful, nor is it suitable for dry-wall planting. When
we finally whipped the central lawn into shape, we realized that a
flowering border would be nice against the wall--a low, narrow border
with colorful bloom all summer long.
To be in proportion and harmony with the setting, the border had to be
completely in miniature--following accepted principles for selecting
and arranging plants, but executed in small scale. Finding the proper
plants has been a challenge; arranging them has been a trial-and-error
proposition, because many varieties are entirely new to us. But last
summer, the little border began to look the way we had visualized
it--taller specimens in the background, ground-hugging cushions facing
them down in front, small groups of straight spires for accent at
strategic intervals. It will probably take another season or two to
perfect the blending and contrast of flowers and foliage, and to get
the most colorful and constant succession of bloom.
This is not, of course, our first acquaintance with miniature
perennials; and it couldn’t possibly be our last. They combine
beautifully with small shrubs, show off to advantage in small rock
gardens, add an artistic finishing touch to garden pools, birdbaths,
and other ornaments. They’re at their very best in outdoor planters and
raised beds on patios and terraces, and in ribbon edgings along walks
and walls.
Although they’re precious in flower, many varieties--candytuft,
lavender, sempervivum, thyme, plumbago, to name a few--are equally
decorative without bloom. This is a valued advantage when planting
space is limited. Gardeners with limited time use perennials lavishly
because, once established, they’re mostly permanent, and they require
a minimum of care. Somehow, I sympathize with a writer who found more
pleasure in spring’s tufts of fresh new growth than in the full bloom
of summer. Nostalgically, one welcomes the return of an old friend;
practically, one knows it will tend to its business of growing and
flowering with very little personal attention.
This leads us to the question, “How perennial _is_ a perennial?”
and to the obvious answer, “It depends....” To begin with, it should
live at least three years in your garden. After that, some varieties
need to be lifted and divided into smaller plants with fresh new
vigor; some may need to be replaced completely; some few may grow on
indefinitely without renewal, or may replace themselves with seedlings
that are often of doubtful value.
In the language of the catalogues, a “hardy” perennial is one that
can withstand fairly severe winter cold, and may not be hardy in
Southern gardens where it is not frozen into dormancy. Most hardy
perennials are “herbaceous”--the stems usually die back to the ground
each winter; some few have stems that may or may not be somewhat woody
and persistent. A “tender” perennial is likely to be killed by cold
weather, and is grown as an annual in the North, if it is grown at all.
The life cycle of a biennial extends over two years. It is grown from
seed, may or may not need special protection to carry it over a cold
winter, produces flowers and seeds the second year, then dies. Some
biennials sow themselves with such faithfulness they’re regarded as
perennial. The comparatively few biennials among flowering plants are
grown much like perennials; miniature varieties are covered in this
chapter.
Originally, I was firmly resolved to admit as miniatures only those
perennials that grow less than eight inches high. But I couldn’t resist
stretching the limits an inch or so to allow for a ten-inch flower stem
above a small, flat rosette of leaves; and I found that the height
limitation allowed free entry to some rambunctious spreaders that could
quickly ruin a miniature garden. So I finally settled on biennials
and perennials that are miniature in general appearance and habit,
without strict measurements, and with flowers and foliage in suitable
proportion for miniature gardens.
For the first year or so, locating some of the small perennials we
wanted was rather like a treasure hunt; we never knew where we’d find
a clue. Occasionally, we’d spy a prize on a visit to a local nursery.
Frequently an advertisement or a tip from another gardener would give
us the name of a promising mail-order supplier. Those who specialized
in rock-garden plants proved to be particularly fruitful prospects.
Often, we started our plants from seeds and discovered later that
mature plants were available, had we known it. Now, we have quite a
list of sources for miniature perennials which we happily share with
you, beginning on page 259.
In selecting suitable varieties, decorative effect is naturally the
first consideration--size, habit, and blooming season; color and
texture of flowers and foliage; how the plants fit into your design
and planting plan. Equally important is hardiness; not only ability
to survive a cold winter, but also adaptability to other climatic
conditions. Some perennials simply will not grow where summers are
hot and dry; others will live but can’t mature enough to flower where
nights are cool or growing seasons are short.
Like other types of plants, perennials should be selected according to
their cultural needs, and should be planted only where they can get
the amount of sunlight and moisture they need, and where the soil is
suitable or can be made so. An acid-loving plant in neutral or alkaline
soil is a poor, short-lived thing; a moisture-lover withers pitiably
where it’s dry as a desert most of the time; a “hardy” perennial won’t
be hardy unless its environment is to its liking.
PLANTING AND CARE
Unless it’s utterly impossible, we do all our planting in the spring,
so there is plenty of time for plants to develop vigorous root systems
before a mean Connecticut winter comes along. This is particularly
important to shallow-rooted perennials, and to any that are planted in
windy, exposed sites. But for us, it also includes spring-flowering
varieties. In spring we’ve planted dormant roots with or without mere
nubbins of new growth, and plants that were fully leaved out and
bursting with buds, with very little loss. But fall planting has proved
to be a gamble; and if we’re forced into it, we’re more likely to find
room in the cold frame for the new arrivals until spring.
Of course, this is not usually necessary in more temperate sections
where plants set out in late summer and early fall have plenty of time
to become acclimated before heavy frost. And it can be all wrong for
Southern gardens, where planting during deepest dormancy is often
recommended.
Even if you’re planting only three little pinks in a nook the size
of a lady’s handkerchief, soil should be dug deeply and be suitably
conditioned or enriched, drainage should be made perfect, roots should
be spread out carefully, and watering should be as thorough as if you
were planting a priceless miniature tree or shrub. To prevent a serious
setback from wilting, put up some sort of temporary protection against
sun and wind--an encircling screen of leafy branches, even a tent of
newspaper or old sheeting.
_Soil_
There are few soils that can’t be improved by the addition of organic
matter such as leaf mold, manure, or compost; and few plants that won’t
grow better for it. It helps hold moisture in sandy soil, improves
texture and increases drainage in clay-like soil, enriches ordinary
garden loam. Mix it thoroughly with the soil before you place the
plants. Also before planting, add lime to acid soil for plants that
need it, acid peat for acid-loving varieties if your soil is neutral
or alkaline. Above all, don’t plant anything (except for a few bog
inhabitants) where water stands in puddles. Poor drainage has killed
more perennials than Old Man Winter himself.
_Watering and Mulching_
Most miniature perennials naturally have rather shallow root systems,
so they suffer quickly from drought. Don’t let them dry out seriously
(particularly after transplanting); water often and deeply enough
that the soil below the roots is wet. Thorough watering in late fall,
just before the ground freezes, often makes the difference between
winter-survival and winter-kill.
Mulching with any available, airy material--buckwheat hulls or crushed
sugar cane, for example--will help keep soil moist and will also
discourage germination of weed seeds, thereby saving you a bit of work.
_Fertilizing_
Most miniature plants don’t like or need a heavy diet. A light
top-dressing of balanced fertilizer, in early spring, is usually enough
to nourish them without forcing soft and straggly growth. Reluctant
bloomers may need a small ration of superphosphate or a booster drink
of liquid-manure “tea” as flowering time approaches.
_Pruning and Grooming_
To keep them compact and attractive, some varieties should have growing
tips pinched out once or twice in spring and early summer; others may
have a few long, straggly stems to be removed; some carpeting types
should be sheared off after flowering. Always pick off faded flowers
unless you have reason to want the seeds.
In fall, when foliage is frostbitten, cut back the old stems and take
them away, along with any fallen leaves or other debris, to be burned.
Many diseases and insects winter over in decaying vegetable matter.
_Insects and Disease_
Our trusty duster or sprayer, filled with an all-purpose
insecticide-fungicide formula, gives all our garden plants a preventive
treatment several times a season. So far, this has been enough to keep
problems and pests away. For some special infestations or epidemics, we
keep a few specific remedies on hand--sulfur for powdery mildew, and
Aramite for mites, for example.
_Winter Protection_
In our area we never know whether winter will bless us with a constant
covering of snow, or the ground will be bare and exposed to alternate
freezing and thawing that “heaves” tender roots up out of their beds.
After the ground is frozen two or three inches deep, we cover sleeping
perennials with a light blanket of salt hay or, sometimes, evergreen
boughs. Crowns that stay evergreen are surrounded by a collar of sharp
sand. Questionably hardy varieties are lifted and moved to the cold
frame.
In spring, as the weather begins to warm up, we remove the protective
mulch a bit at a time. There’s a fine line between taking it off
prematurely, thus exposing new growth to a late freeze, and leaving it
so long that the soil underneath gets soggy and the roots rot. But, rot
can be fatal, and frozen tips of new growth are not, so we remove the
winter covering as fast as we dare.
PROPAGATING MINIATURE PERENNIALS
One item in our Connecticut landscape that’s completely out of scale
with its surroundings is the monstrous cold frame near the back
boundary line. The cement-block wall goes down below the frost line,
and up high enough to make room for winter storage of fairly good-sized
plants. The discarded storm windows are hinged across the back and
completely removable in summer, when they are replaced by light wooden
frames of the same size with laths nailed a lath-width apart. The
construction slants toward the south, to make the most of all winter
sunshine; light shading is necessary in summer to protect tender
seedlings and rooting cuttings.
The cold frame serves dozens of purposes and has more than paid
for itself with plants it has protected or produced. When we plant
perennial seeds in the cold frame, we throw a piece of burlap across
the top and keep it moist until they germinate. Tender seedlings spend
their first winter within its walls, and so do newly rooted cuttings.
Questionably hardy perennials or any that we acquire in fall are held
over until spring. Every year, it seems as if we take more out of the
cold frame than we put into it!
Other, smaller, portable devices are equally useful for all kinds of
summer propagating. Low square or rectangular wooden frames can be
set over an area of prepared soil and the top covered with glass or
polyethylene to keep the soil from drying out. An empty fruit crate
from the grocer can be equipped with a glass or plastic top. A few
cuttings can be rooted in soil in some shady spot with a clear glass
jar inverted over them. There are many devices that keep soil moist
and air humid while seeds germinate or cuttings root. How large or
elaborate yours should be depends on how much propagating you want to
do.
_Seeds_
Many hard-to-find miniature perennials can be easily grown from a
twenty-cent packet of seed. You can also harvest seeds from your own
plants; but only natural species will “come true.” Complicated hybrids
will have unpredictable offspring, most of them not particularly
desirable.
We plant seeds of most biennials and perennials in June, when the soil
is comfortably warm and the seedlings will have the whole summer to
grow large and lusty. Some of our own seeds that ripen in midsummer are
planted as soon as we can harvest them; those that mature later are
usually stored on a cool shelf in the cellar in plastic boxes or little
pill bottles that keep them dry.
Soil for the seed bed is sifted to remove pebbles and debris, and mixed
with equal quantities of sharp sand and peat or sieved leaf mold. To
prevent “damp-off,” a fungus that chokes off stems at the soil line,
soil should be sterilized if at all possible. Small quantities may be
baked in the oven. Special easy-to-use fungicides are also available;
follow label directions.
[Illustration:
Rocks, water, and planting--an effective combination of all the
elements of a rock garden. (_Mr. and Mrs. Norman Cherry_)]
Most seeds are covered to the depth of their diameter; very fine seeds
are merely firmed down into the soil. Seeds with hard coats may be
gently nicked with a knife or soaked in water for a day or so. Some
seeds, like primroses, need to be treated as if they had wintered
outdoors before they will germinate. You can put them in moist sand
in a small, tight container and alternate freezing in the ice
compartment and thawing in the warmer part of the refrigerator for
several days. Or you can plant these seeds in a small box or flat of
their own and leave them outdoors, in a protected spot, where winter
will supply its own natural conditions.
[Illustration: Cold frame planted and ready for top made from
discarded storm windows]
Some seeds germinate faster in the dark, some with light; some like
cooler temperatures than others; some come up in seven days, some
take months or even a year. Seed packets usually supply pertinent
information.
Seeds will not germinate in dry soil, or if allowed to dry out even
temporarily during the critical period. To avoid washing out fine
seeds, water gently with a fine mist, or set the flat or other
container in water up to the level of the soil inside. When the soil
surface looks shiny and moist, remove the container and set it aside to
drain.
When the first “true” leaves are of fair size, transplant the seedlings
to peat pots, or flats, or rows in a prepared bed or cold frame. Shade
against sun and wind until they resume growth.
_Stem Cuttings_
Many perennials can be propagated easily and in quantity by rooting
softwood cuttings like those of trees and shrubs. Tip cuttings three
or four inches long are usually best, with all the flower buds and the
lower leaves removed. Some types, such as dianthus and lavender, root
faster and more surely if the cutting is taken with a heel.
For spring-flowering varieties, take stem cuttings after flowering
has finished and up until midsummer; for those that bloom later, take
cuttings in May or June.
_Division_
This is a wonderful way not only to increase perennials, but also to
keep them young and vigorous. How often you divide them depends on each
plant’s individual performance. When growth is so thick it seems to be
choking itself, when there’s little healthy new growth and a poor show
of bloom, when a clump or crown becomes tough and hard in the center,
it’s usually time to refresh the plant by division. Some plants need it
almost every other year, some not for many years.
How you divide a plant depends upon how it grows. If there is a central
crown of leaves, it can be cut cleanly into two or three sections,
each with its own share of roots. Or there may be new, young crowns
clustered around its edge that can be pulled or cut off. If the plant
simply has a crowded colony of stems and fibrous roots, you can often
pull it apart gently into several pieces. Or if it’s the type that
sends out rooting runners, you can sever these and replant them.
Generally, the old, tired center of the plant is discarded.
In cold climates, even spring-flowering perennials are most safely
divided very early in the season, when new growth is beginning. Cool,
moist spring weather favors rapid recovery from the operation, and
there is plenty of time for the new plants to mature before fall.
Summer-flowering and fall-flowering types are also divided in earliest
spring. In humid climates the spring-bloomers can be divided in August
or early September.
_Layering_
Almost any perennial with low or low-hanging branches can be propagated
by pinning a stem to the soil, several inches from the growing tip.
When new growth appears, cut off the rooted stem and transplant it.
This propagating method may not produce great numbers of new plants at
one time; but it is surely one of the easiest and least troublesome
practices--and particularly safe because the new plant is supported by
the parent until it is well rooted.
I’ve been intrigued with one good gardener’s method of creating a low
hedge from one plant of dwarf lavender. She layered one stem at each
side of the original plant. When these two new plants were fairly
mature (but not cut away from the old plant), she layered one stem
of each. By repeating the process, and locating each new layer in a
straight line with the last one, she can extend her hedge as far as she
wishes and plant it as she goes, along any lines.
ROCK GARDEN PERENNIALS
=Achillea= _Compositae_ Yarrow, Hilfoil
Resembling the field yarrow, but dainty, mottled, and tufted. The
leaves, some finely cut and ferny, wear thick wool coats. The saucy
flowers are in heads, some flat-topped and not unlike daisies.
_ageratifolia aizoon (Anthemis aizoon)_--Six-inch mat of
silver-haired, uncut leaves topped with bright white flowers in
May and June.
_clavennae_--Tufts of hoary, fine-cut leaves less than a
foot high, tight round white flower heads three-fourths of an
inch across in May and June.
_tomentosa_--Best-known little species, quickly makes a
thick mat of semi-evergreen gray-green leaves six inches tall.
It has sunny yellow flowers from June to midsummer. The variety
aurea has more golden flowers and blooms earlier; nana is a true
midget and makes a thick carpet studded with many white flowers.
Five-inch ‘Moonlight’ has flowers of sulfur yellow, and greener
foliage.
_umbellata_--Four-inch mounds of fuzzy, silvery, ferny
leaves. It has cream-white flowers in June and is evergreen in
temperate areas.
CARE. Any soil, even sandy or poor. Dryish to moist. Sun or very light
shade. Easy to grow.
PROPAGATION. Division in spring or fall, seeds (flowers the second
year).
SPECIAL USES. Rock plantings, dry-wall planting, edging, ground cover,
pavements.
=Aethionema= _Cruciferae_ Stone-Cress, Persian Candytuft
This is a heathery little shrub-like perennial with slim leaves and
steely-blue needles, cheerful clusters of flowers at the stem tips in
May and June. It is often compared to a minuscule daphne.
_armenum_--Neat tufts of short, sharp leaves and petite
pink flowers in June. It is never over four inches high.
_iberideum_--Low, crowded, and cushiony-minute with
gray-green leaves and large white flowers in short clusters.
This one is earlier than other varieties, blooming even in April
if the weather is favorable. (Needs gritty soil with some lime.)
_schistosum_--By comparison this one is a giant growing
to eight or ten inches, with two-inch leaves and fragrant pink
flowers.
CARE. Soil light, sandy, well-drained, and gravelly; dry; sun. Hardy in
southern New England. Give protection in severe winters.
PROPAGATION. Cuttings in summer, division and seeds in spring.
SPECIAL USES. Rock gardens, dry-wall planting, edging, borders.
=Ajuga= _Labiatae_ Bugle
This is a low, creeping or spreading perennial with pinwheels of rather
coarse leaves and small blue flowers which come in May and June. It is
of miniature height and should only be planted where you can control
it, or want it to spread. Some of the better-known varieties are:
_genevensis_--Oval toothed leaves, light green. Flowers
deep blue.
_pyramidalis_--Less likely to spread and stays neat and
small. Flowers blue and slightly larger than those of other
varieties.
_reptans_--Also known as carpet bugle, it is nearly supine,
with stems that root as they creep. Flowers blue or purplish.
Variety alba has white flowers; variegata, foliage marked with
cream and pink. Rubra pink flowers.
‘Silver Beauty’--Compact and ground-hugging. White markings on
leaves give a silvery appearance. Blue flowers.