The Bright Stuff: Selecting Annuals and Biennials

Fill your garden with a sea of color using inexpensive annuals and biennials.

Colorful Mix of Papaver Rhoeas in Sunny Meadow

Colorful Mix of Papaver Rhoeas in Sunny Meadow

Annual poppies creates an absolute vision of beauty in full bloom when they carpet a whole field, nodding in the breeze.

©2011, Dorling Kindersley Limited

2011, Dorling Kindersley Limited

You will find a huge choice of annual and biennial seeds online or via mail order from specialty suppliers. If you don’t have the space or time to sow seeds, then you can also choose from a wide selection of young plants at a specialty garden store. 

Hardy annuals, such as love-in-a-mist (Nigella) and pot marigolds (Calendula), can be sown directly outside in midspring; sow them where you want them to flower. 

Sow tender and half-hardy types in the early spring in a heated greenhouse or on a windowsill indoors. For these you will need seed trays or pots, seed compost and some patience, because they must be nurtured until they are ready to go outside after the last frost. If you sow with care, you can be rewarded with 20–50 plants or more per packet.

Plug plants offer another economical way of purchasing annuals and biennials. These are seedlings that need to be potted into larger containers or trays when you receive them, but they cost much less than mature plants. Specialty suppliers offer a good range, although not as extensive as the choice of seeds. Finally, you can buy mature plants, which provide instant effects and are ideal if you want just a few plants to fill a summer container or to add color to a border. Buying young annual plants is the quickest way to fill containers and borders with color.

Providing Ideal Conditions

There is a range of annuals and biennials for almost any location, so select those that suit your site.

To encourage the best performance from your plants, you will need to provide them with sufficient light — browse through a seed catalog, and you will find that the majority of annuals listed prefer a sunny location. Colorful types, including marigolds, lobelia, petunias and asters, will light up a sunny spot with their striking blooms. There are a few plants, however, including Impatiens, nasturtiums, and Nemesia, that are happy in partial shade, while foxgloves (Digitalis) and forget-me-nots (Myosotis) are among the biennials that will thrive in partially shaded sites.

The majority of sun lovers prefer average to free-draining soil and can tolerate periods of drought. For example, cornflowers and annual poppies are ideal for a wildflower meadow on a large expanse of dry, sandy soil. These annuals perform best on infertile soil; if yours is too rich, you will find that grasses and weeds dominate and the flowers will not be able to compete. To remedy this, strip off the top layer of soil before sowing, since this usually contains the highest levels of nutrients.

Annuals from tropical areas, such as Amaranthus and coleus (Solenostemon), as well as woodlanders like foxgloves, prefer moist soil conditions. Also, annual bedding plants used for summer container displays, such as petunias, asters and marigolds, will perform best in moist potting compost. Plant a partially shady site with the blue flowers of Myosotis sylvatica ‘Music’.

Easy Seeds

Growing annuals and biennials from seed is not difficult as long as you can provide the right conditions at the crucial stages of their growth — check individual seed packets for site and soil advice. If you are new to sowing seeds, however, and want to guarantee success, put the following at the top of your list: hardy nasturtiums, pot marigolds, love-in-a-mist, California poppies, English marigolds, Iberis andCerinthe major. These are among the most dependable hardy plants. Sow outdoors where they can flower in free-draining soil and a sunny site to promote a good display of blooms.

Sow the following tender seeds indoors in the early spring for a sparkling collection of summer flowers: annual dahlias, cosmos, petunias (select the upright plants as the trailing forms are less reliable), BidensTagetes and zinnias.

Self-Seeding Plants

Annuals and biennials that self-seed either true to type or with minor variations include: 

  • Agrostemma (Corn cockle)
  • Calendula officinalis (Marigold)
  • Centaurea cyanus (Cornflower)
  • Clarkia amoena (Satin flower)
  • Collinsia bicolor (Chinese houses)
  • Digitalis purpurea (Foxglove)
  • Eschscholzia californica (Californian poppy)
  • Hesperis matronalis (Dame’s violet, sweet rocket)
  • Lunaria annua (Honesty)
  • Malcolmia
  • Myosotis (Forget-me-not)
  • Oenothera biennis (Evening primrose)
  • Papaver (Poppy)
  • Silene armeria (Campion)
  • Tropaeolum majus (Nasturtium)
  • Verbascum (Mullein) 

Plant Care

Watering young seedlings is vital if you want them to grow into mature, healthy plants, but once they are established, many require little extra irrigation except during long periods of drought. The exceptions are those grown in containers, which will need watering daily during hot spells and every few days at other times.

Feed container-grown annuals with slow-release fertilizer granules when you plant them. This one application should provide them with sufficient nutrients for most of the season, but if displays start to flag at the end of summer, top them off with a dose of liquid feed.

Remove faded blooms regularly since this encourages the plants to form flowers rather than putting their energies into making seeds. Don’t deadhead the flowers if you want to collect seeds to sow next year.

Flowers for Bees and Butterflies

Many annuals and biennials are rich in nectar and attract pollinating insects, such as bees, butterflies, hoverflies and moths. These beneficial insects are especially useful in productive gardens, where pollinators are needed to set fruits, such as tomatoes and strawberries, and seeds like peas and beans.

Another good reason to stock your garden with insect-friendly plants is to maximize bee food supplies since worldwide populations of these vital insects are in serious decline as a result of the loss of their preferred flower-rich habitat, and any extra help you can give them will benefit your garden too. The best nectar-rich plants to include in your displays are spring-flowering Iberis, sweet alyssum (Lobularia maritima) and sweet williams (Dianthus barbatus). Cornflowers (Centaurea cyanus), corn cockles (Agrostemma githago) and other meadow flowers, the yellow and white poached-egg plant (Limnathes douglasii), pot and French marigolds (Calendula and Tagetes), California poppies (Eschscholzia), Cerinthe major and Phacelia tanacetifolia produce blooms for insects throughout the summer.

Cut Flowers

Some annuals make stunning cut flowers for the home. Combine Moluccella laevis, with its tall spikes of unusual green flowers, with larkspur (Consolida ajacis), and try the annual aster Callistephus chinensis, in late summer and fall arrangements, or Bracteantha, which can be used fresh or dried. Learn more about which annuals will work best in your home design below:

  • Moluccella laevisThe bells of Ireland make the perfect foil for colorful flowers. Grow in full sun in moist, free-draining soil. Chill the seed for five days in the refrigerator, and soak before sowing.
  • Consolida ajacis (larkspur): This pretty annual looks like a dwarf delphinium with spikes of blue, pink or white flowers. Sow seed in spring, and enjoy vases of blooms all summer.
  • Callistephus chinensis: Sow seeds of the annual or China aster indoors in early spring. Plant out after last frost in a sunny site with moist, free-draining soil. Buy long-stemmed varieties for indoor displays.
  • Xerochrysum bracteatumThe everlasting flower is so-called because it will literally last for years when dried. Sow the seed indoors in early spring, and plant out after the last frost in a sunny site and free-draining soil. 
Keep Reading

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