What is an Annual?
The term annual refers to those
garden flowers that complete their life cycle in one growing season.
This means seed is planted in the spring, the plants grow, flower,
set seed and then die usually after the frosts in the fall.
Annuals can also be classified based upon their tolerance to and
ability to withstand cold. Understanding how annuals are classified
based upon their tolerance to cold temperatures can be very useful
in extending the gardening season. This allows you to plant well
before the last frost in the spring and well past the first frost in
How to Grow Annual Flowers
Until a few years ago,
if you wanted to grow annual flowers, your choices were limited
to geraniums, impatiens, marigolds and red salvia. But today,
most greenhouses offer an eye catching array of choices. Whether
you're planting a window box, lining your sidewalk, or spicing
up your perennial garden, here's how to make the most of what's
Strictly speaking, an annual plant is one that
completes its growing cycle (grows from seed, flowers
and produces seed) in the course of a single growing
season. In other words, annuals pack a lot of living
into a short span of time.
But beyond this simple definition, there is an even wider
range of plants that we treat as annuals. Some, such as
impatiens, heliotrope and tuberous begonias, are actually tender
or "half-hardy" perennials that can't survive even a light
frost. On the other hand, some annuals, such as pansies and
ornamental cabbage, are extremely cold-hardy and can withstand
freezing temperatures quite well.
One of the best things about annuals is their incredible
diversity and versatility. Using them allows you to compose
really exciting combinations of color, form and texture that
will last all season long. Colors range from bright midsummer
favorites such as zinnias and Mexican sunflowers, to the subtler
pastel shades of stock or lavatera.
You can also select annuals for your garden based on
characteristics other than flower color. There are annuals that
are tall, medium, short or climbing; ones that prefer either
full sun or partial shade; and those with special virtues, such
as delightful fragrance (stock, mignonette, nicotiana) or
attractive foliage (caladium, coleus, dusty miller).
Perennials Grown as Annuals
A tender perennial is one that won't survive the winter in
your climate. Many gardeners simply treat these plants as
annuals, enjoying them for one season and letting them die in
the fall. Other people move plants inside at the onset of cold
weather: treating them as houseplants over the winter; taking
cuttings and starting new plants; or simply digging up and
storing part of the plant (usually the roots or bulblike
structures) indoors for replanting the following year.
Examples of perennials that are commonly grown as annuals
include the more tender flowering sages (Salvia coccinea,
S. patens, S. splendens, etc.), verbenas, and hyssop (Agastache
spp.). Geraniums and scented geraniums (Pelargonium spp.)
can be grown outdoors either in beds or pots during the summer,
then brought indoors at the end of the season: to bloom in pots,
to store in darkness for replanting, or to use as cuttings for
new plants. Petunias, coleus, and sweet-alyssum (Lobularia
maritima) are other plants that can be over wintered in pots
and replanted the following year.
If you have a sunspace or attached greenhouse that receives
plenty of winter sunlight and doesn't get too cold at night, you
might try growing some of the interesting "annuals" that in
their native habitats are actually perennial shrubs and trees.
For example, if given year-round protection, fuchsias grow
rapidly, reach anywhere from 18 inches to 12 feet or more, and
produce their beautiful pendulous blossoms in shades of red,
purple, and white nearly all winter long. Brugmansia, or
angel's-trumpet, can grow to 15 feet tall in greenhouse
cultivation. Its trumpet-shaped flowers are fragrant and
beautiful, but don't grow it in the house if you have small
children; the plants are extremely poisonous.
Flowering plants that grow from tender bulbs, such as
dahlias, gladioluses and cannas, are often planted as annual
flowers in cutting gardens or mixed ornamental borders. They,
too, are tender perennials, and most varieties won't survive the
winter outdoors in most of North America. However, it's easy to
dig up these bulbs at the end of the growing season and store
them indoors for replanting the following year.
Starting Annuals from Seed
Seeing all the annuals offered for sale at nurseries and
garden centers in the spring, you might wonder who would go to
all the trouble of starting their own annuals from seed. There
is an economic advantage, of course. A $2 packet of seeds might
grow four large flats of alyssum plants, which would be a
savings of roughly $70 over buying the plants from a nursery.
An equally compelling reason for starting your own plants
from seed is that even the best garden centers don't carry the
full selection of worthy garden annuals. Most sell the popular
bedding plants, but it can be hard to find old-fashioned
annuals, such as love-lies-bleeding (Amaranthus caudatus),
four o'clocks (Mirabilis jalapa), or lavatera (Lavatera
Part of the reason for this absence stems from economics
(supply and demand) and part is due to the nature of the plants
themselves. Garden centers like to sell six-packs of plants that
are already in bloom; that way customers know what they're
getting, and know that the plants will probably continue
blooming after they get them home and in the ground. Instant
Yet many fine annuals won't start blooming in nursery
six-packs. They're either too tall, don't like to be
transplanted, or just won't flower until they have been in the
ground for a couple of weeks. If you want to experiment with the
whole palette of annuals, eventually you will want to grow some
of your own plants from seed.
Many annuals are easy to seed directly into garden soil.
Others are best started indoors under lights in late winter or
early spring. Consult seed catalogs, seed packets or the book From Seed to Bloom by Eileen Powell for information on
specific plants. Generally speaking, annuals fall into three
main categories, which determine when and where you should sow
their seeds. For all categories, a good rule of thumb is to
plant seeds at a depth of two or three times their diameter.
Some annuals are so good at fulfilling their mission in
life flowering and setting seeds that they will self-sow
readily under the right conditions and produce brand-new plants
the following year. Common annuals that can self-sow vigorously
include ageratum, petunia, foxglove, annual larkspur,
forget-me-not, calendula and wild or striped mallow (Malva
Can be direct-sown in the garden as
early in the spring as the soil can be worked. For an earlier
start, sow them indoors in flats eight to ten weeks before the
last spring frost date, and transplant them to the garden about
a month later, after hardening them off.
Some hardy annuals can also be direct-seeded in the fall, and
these plants will flower much earlier than plants seeded in the
spring. When fall seeding, plant the seeds a bit deeper than you
would in the spring, and spread some mulch over the seedbed
after the ground has frozen.
Examples of hardy annuals include bachelor's-buttons,
calendula, spider flower (Cleome hasslerana), pinks (Dianthus
spp.), larkspur, linaria, Shirley poppies (Papaver rhoeas),
nigella (love-in-a-mist), scabiosa (pincushion flower),
snapdragons, lavatera, annual baby's-breath (Gypsophila
elegans), heliotrope, stocks and sweet peas.
These can be direct-sown outdoors
after the threat of hard frost (temperatures below 25Â°F) is
past. Indoors, start seeds in flats six to eight weeks before
the last spring frost date, and harden off the plants before
transplanting them to the garden. Once they have hardened off,
half-hardy annuals can withstand a light frost.
Examples include statice, nicotiana, painted-tongue (Salpiglossis
sinuata), China aster (Callistephus chinensis), and
various types of salvias and chrysanthemums.
Seed can be sown directly in the
garden only after all danger of frost is past. For an earlier
start, sow seed indoors four to six weeks before the last spring
frost date for your area. Examples include marigolds, morning
glories, zinnias, sunflowers and tithonia (Mexican sunflower),
cosmos, amaranth, ageratum, celosia and gomphrena (globe
Propagating from Cuttings
Late summer or early fall is an ideal time to take cuttings
from annuals such as geraniums, coleus and impatiens, potting
them up for winter bloom indoors or to hold them over for the
following spring. The following steps will help ensure success.
1. Clip off any flowers or flower buds on the plant. This is
done to focus the plant's energy into developing new roots on
the stem cutting.
2. Select healthy stem cuttings (preferably healthy growing
tips or side shoots) that are 2 to 6 inches long. Strip off any
bottom leaves where the stem will be inserted in the rooting
medium (either potting soil or water). Dip the cut end of the
stem into a rooting hormone powder to encourage rapid root
3. Insert the cutting in potting soil (not a soilless
seedstarting mix) and water the container. Cover the flat or pot
with a clear plastic bag to create a moist, humid atmosphere.
Don't let the plant leaves touch the side of the bag because
this will cause rot.
4. New roots should develop in one to three weeks. To test,
gently tug on the cutting. Pot up the new plants in 4- to 6-inch
containers and keep out of direct sunlight for three days. After
this time, place the plants in a sunny location.
5. An alternative method of rooting plants, such as begonias,
coleus or geraniums, is to place the stem cuttings in a glass of
water to develop roots. Change water every few days until plants
develop roots, and add a little soil to the jar after new roots
appear. Plant rooted cuttings in 4- to 6-inch containers filled
with potting soil.
6. Once the new plant is well established, pinch off the stem
tip to encourage fuller growth and more abundant flowers.
Growing and Care of Annuals
Soil preparation and planting: In general, annuals
prefer well-drained soil with a pH between 6.3 and 6.7. Digging
in a good quantity of peat moss or compost will help to build up
the soil's organic matter and allow the plants' roots to spread
quickly and get off to a good start.
Set out young plants at the recommended spacing, to prevent
them from crowding each other once they have grown and matured.
If you've purchased plants in flats from a garden center, the
plants will likely be somewhat pot bound when you remove them
from their cells or containers. Before placing them in the
planting hole, gently break apart the root mass; this encourages
roots to spread quickly into the surrounding soil. Fertilize at
planting time with an organic or slow-release fertilizer.
You need to pay attention to whether a particular plant is
hardy, half-hardy or tender before deciding when to transplant
it. Some nurseries sell plants with labels that identify
hardiness; when in doubt, put your annuals out after all danger
of frost has passed. Another crucial factor, of course, is
whether a particular plant prefers sun or partial shade.
If you need to hold plants in flats for more than a couple of
days at home, be sure to water them and keep them in a partly
shady, protected spot, such as a porch or under a tree. Don't
leave them in a garage or other structure where you store cars
or gasoline-powered machines; ethylene gas can cause flower
damage and leaf drop. The best advice is to transplant annuals
to the garden as soon as possible after bringing them home.
Care of annuals: Once they start blooming, most
annuals will flower all season long, until cold temperatures or
frost put an end to their display. However, to keep them
flowering and looking good, you will need to perform some simple
but easy maintenance.
Deadheading is the most important task, and it involves
pinching off old flowers just as they begin to fade. The reason
for doing this is simple. Annuals live to flower quickly,
produce seed and die. So long as you keep deadheading blossoms,
the plants will continue to produce flowers; once you stop, the
plants will reduce or stop flowering, and put their energy into
maturing seeds. Pinching off spent blooms is quick and easy, and
it ensures season-long bloom.
If you've fertilized at planting time as recommended with an
granular, organic, slow-release fertilizer, you shouldn't have
to fertilize annuals again during the season. With annuals, the
flowers are the thing, and over fertilizing can lead to lush
foliage growth, which is really beside the point. The primary
exception is container-grown plants, which usually need to be
fertilized with water-soluble fertilizer every couple of weeks
to maintain a colorful show.
Annuals have shallow root systems and so require a regular
supply of water. Avoid overhead watering if possible, which can
stain some types of flowers (such as petunias), and make them
look unattractive. It also can contribute to a buildup of
botrytis fungus, which can affect plants such as zinnias,
geraniums, and marigolds. For best results, use a soaker hose or
a drip irrigation system, or direct your watering can right at
Designing With Annuals
When shopping for annuals, it helps to think in terms of
color and form.
Because they only stay in the garden for one season, annuals
offer maximum flexibility. If you don't like the effect you've
created one year, you can simply chalk it up to experience and
try again next year, without having to move plants around as you
would with perennial plants.
The most popular and widely grown annuals are used as bedding
plants combinations of brightly colored flowers and foliage
plants in a bed that is accessible from all sides for visibility
and ease of maintenance. Such formal plantings can be especially
effective if you plant a solid block of plants of the same
variety and color. Separated by neat strips of lawn, such
single-color plantings lend a nice formal effect to the garden.
An even more impressive sight is a massed single-color
planting divided down the center by a band composed of a flower
that has a different, but complementary, color or growing habit.
For instance, a dark, vivid color, such as the bluish purple
flowers of border lobelia (Lobelia erinus), might combine
well with the white flower mounds of sweet alyssum (Lobularia
maritima). Both plants are tender perennials grown as
annuals, and both are similar in growing habit: low, mounding
and normally used for edging beds.
Annuals work equally well in less formal designs, and they
fill an important role by giving you a brilliant palette of
color with which to work. They can be inserted into open spots
between and around perennials and flowering shrubs. Adding
annuals to a perennial border can bolster the effect of the
whole, ensuring a continuity of color and interest even when the
perennials are not in bloom. They are great for creating
rhythmic splashes of color, for linking different parts of the
garden together, and for helping to carry a particular color
theme through the garden during the entire growing season.
Some of the best annuals for mixed border plantings include
tall species such as nicotiana (flowering tobacco), cleome
(spider flower), lavatera, Shirley poppies, foxglove, matricaria
or the vibrant orange Mexican sunflower (Tithonia
rotundifolia). For mid- and late-season color at the front
of the border, use annuals such as impatiens, matricaria,
Salvia horminium and sweet alyssum.
With all their different heights, colors and forms, it's
entirely possible to plant a spectacular border composed of
annuals alone. Since most annuals flower at the same time, and
over an extended season, you may want to choose varieties that
will complement one another. You can strive to create a
particular color scheme (pink, blue, and white; yellow, blue and
orange), or simply go for a full-blown riot of color.
One way to create a more interesting and designer effect is
to include annuals that are grown for their attractive foliage,
which can act as a foil for the bright blooms of other plants.
The silver foliage of dusty miller (Senecio cineraria) is
an old standby in the annual garden, but there are lots of
other, lesser-known foliage plants as well, including cannas,
which have tropical-looking, sometimes bronzed leaves;
plectranthus, with its soft, silvery leaves; and perilla (Perilla
frutescens), a beautiful herb whose dark purple, fringed
leaves are particularly effective with white and pink-purple
Climbing annuals are another good choice, especially for
cottage garden settings and containers (window boxes, hanging
baskets, etc.). They have an old-fashioned, informal quality and
will create a colorful living tapestry on fences, screens,
trellises, or other supports. Plenty of people grow morning
glories (Ipomoea purpurea and I. tricolor) and
their close relatives, moonflower (I. alba) and cardinal climber
(I. x multifida). But that scarcely scratches the
surface of great climbers..
Containers and Overwintering
The perfect choice for growing in containers, annuals work
well either alone or in combined plantings. Be imaginative when
selecting containers, and if you have the room and the
resources, don't just stick to the tried-and-true terra-cotta
pots. Window boxes are designed for annuals, especially ones
that cascade over the sides. The same holds true for hanging
containers, where trailing varieties, such as the old-fashioned
nasturtium Empress of India', hang down and make a pretty
display. For more information, read Planting a Winning
Impatiens are particularly beautiful when planted in a
container set in filtered shade. Most commonly you'll see them
planted in the round, usually in a large container like a half
whiskey barrel. To set your display apart, try experimenting
with something a little different. An old soapstone sink would
make an excellent bed for impatiens or other colorful annuals,
as would a planter you've either bought or made from hypertufa
(a kind of artificial stone). Brown fiber pots and planters are
widely available, and will last for several seasons. They're
also light (at least when empty) and easy to move.
When planting in containers, make sure that you allow for
adequate drainage. If the pot or container doesn't have drainage
holes, either insert a smaller container that does inside of it,
or cover the bottom of the container with a layer of small
stones or foam peanuts (a terrific way to recycle them).
Like other plants grown in containers, annuals require
regular watering and fertilization throughout the growing
season. In addition, you'll also have to deadhead spent
blossoms. During hot, dry weather, your plants may need watering
once or even twice a day. Certain plants, such as moss rose (Portulaca
grandiflora) and calliopsis (Coreopsis tinctoria),
prefer somewhat dry soil and hot, sunny weather.
Tender annuals should be protected from early frosts. A
stretch of warm fall days often follows the first frosts, so it
pays to cover your plants and prolong the season. Once cool
weather becomes the norm and frost kills off your plants, remove
them from their pots and clean the containers with soap and
water or a dilute bleach solution, to get them ready for next
The end of the growing season doesn't necessarily mean the
end of your annuals. Tender perennial plants already growing in
containers can be cut back and brought indoors, while bedding
plants such as petunias, impatiens, lantana and geraniums can be
potted up and treated to a prolonged season of bloom inside.
Before bringing these plants indoors, check them for insect
or disease problems and either treat them or discard them if you
find any. Cut back the plants by 4 to 6 inches, and place the
pots in a room that gets a lot of light. A greenhouse or
sunspace is ideal, but so are sunny windows with a west or south
exposure. After cutting back the plants, give them a dose of
liquid plant food and they should soon start to develop new
leaves and flowers.
Keep a close eye on any plants you bring indoors, at least
for the first couple of weeks. The shock of being moved inside
makes plants very vulnerable until they become acclimated to
their new growing conditions. Pamper your plants as much as you
can at this time to ease their transition to indoor life.
Some plants can be dug up in the fall, pruned way back, and
stored in a cool, dark place until early spring. This includes
most of the tender perennials, such as brugmansia, datura and
geraniums. Water plants sparingly during this time.
Another strategy for overwintering plants is to take cuttings
in the summer or early fall and start new plants from your old
annuals. This technique works particularly well with coleus,
plectranthus, and licorice plant (Helichrysum petiolare).