Yard and Garden: Annuals for Shade

Considerations when selecting annuals for shade
AMES, Iowa — The garden centers and greenhouses are fully-stocked with annuals for spring planting. Annuals are a perfect addition to the landscape to provide color that lasts throughout the summer. Although most annuals prefer several hours of direct sunlight for maximum growth and bloom, there are a few annuals that prefer the darker corners of the garden. In this article, Iowa State University Extension and Outreach horticulturists answer questions about the annual plants that can be grown in the shady spots of the landscape in Iowa.

How much light do shade gardens receive?

Not all shady garden areas are created equal, and not all shade gardens are void of direct sun. In fact, most shaded areas well-suited for growing annuals should receive some direct light during the day. Shade gardens can be classified as shade, part shade or deep shade based on the amount of direct sunlight they receive. A shade garden is any location that receives one to three hours of direct sunlight each day. Many shade-loving annuals prefer dappled shade or those areas that receive direct sunlight in the morning when temperatures are cooler. Plants may respond differently if the direct light comes later in the day. This light in late afternoon and early evening is typically hotter and more intense. Part shade locations receive three to six hours of direct sunlight a day. Deep shade receives no direct sunlight during the day and can be one of the most difficult locations to grow any plants. Annuals can be the perfect plants for these areas because you can try something new each year and experiment to find the best species for that site.
What are the challenges with growing annuals in the shade?

Often the most prevailing challenge in shade gardens is the competition from trees. The roots of established trees can compete with other plants for moisture and nutrients. In addition, it can be difficult to plant around the tree roots. If digging is too difficult or is causing damage to tree roots, consider growing annuals in a container. Nearly all shade-loving annuals do well in containers or hanging baskets. Because of the lower light levels, shade gardens tend to have cooler temperatures and retain soil moisture longer than sunnier garden areas. Cooler temperatures mean these garden areas warm up later in the spring, and moist soils with low light levels can favor pests like slugs and snails. Deep shade created by buildings, overhangs, walls or fences can sometimes create light levels that are so low that even shade loving annuals cannot thrive. Selecting annuals that prefer cool temperatures, consistently moist soils and/or the appropriate amount of direct sunlight can allow for success despite these challenges.
What annuals are good for shade?

A shade garden receives one to three hours of sunlight a day, ideally in the morning or as dappled light throughout the day. Annuals that can be successfully grown in shady areas include wax begonia (Begonia×semperflorens-cultorum), impatiens (Impatiens walleriana), coleus (Coleus scutellarioides syn. Solenostemon), wishbone flower (Torenia fournieri), Browallia or silver bells (Browallia speciosa), polka dot plant (Hypoestes phyllostachya), caladium (Caladium bicolor), tuberous begonia (Begonia × tuberhybrida) and pansy (Viola ×wittrockiana).
What annuals are good for part-shade locations?

Part shade locations receive three to six hours of direct sunlight a day. Often those annuals that tolerate full shade will grow and bloom even better in part shade locations, especially if the direct sunlight comes in the morning hours. There are several sun-loving annuals that will tolerate part shade locations and still bloom and grow, just not as vigorously as they would in more light. Annuals well-suited for part shade locations include, New Guinea impatiens (Impatiens ×hawkeri), angel wing begonia (Begonia), nasturtium (Tropaeolum), flowering tobacco (Nicotiana), cupflower (Nierembergia), rose balsam (Impatiens balsamina), bachelor button (Centaurea), pinks (Dianthus), bells of Ireland (Moluccella), bacopa (sutera cordata), forget-me-not (Myosotis), baby blue eyes (Nemophila), perilla (Perillafrutescens), heliotrope (Heliotropium arborescens), Persian shield (Strobilanthes dyerianus), Swan River daisy (Brachycome), fuschia (Fuschia) and elephant ear (Colocasia).
What can I grow in garden areas with deep shade?

Deep shade areas received no direct sunlight and many shade-loving annuals may not thrive in these very low light locations. These areas are usually created by buildings, walls or fences and further shaded by nearby shrubs and trees. If possible, limb up trees or shrubs to allow more light into the area. Despite these very difficult growing conditions, a few annuals can be potentially good, colorful additions to deep shade. Impatiens (Impatiens walleriana), caladium (Caladium bicolor), tuberous begonia (Begonia × tuberhybrida) and most tropical houseplants can be good options for deep shade.
Can I use houseplants in my shade garden?

Yes! Most tropical plants grown as houseplants are native to the shady understory of tropical forests.Their tolerance of low light levels is what makes them good houseplants and can also make them a great way to brighten shady garden areas. Houseplants can be treated just like annuals; purchased from garden centers in spring, planted in the garden and allowed to be killed by frost in fall. Established houseplants from indoors can be moved to full or part shade locations after the danger of frost has passed. Be sure to acclimate the plant to the new light conditions outdoors by transitioning them to more light slowly over seven to 10 days. Bring the houseplant back indoors in the fall once nighttime temperatures start to dip below 50 Fahrenheit at night. Houseplants that are good to grow as annuals in the shade garden include, Boston fern (Nephrolepis), pothos (Epipremnum aurcum), rex begonia (Begonia), philodendron (Philodendron), Swiss cheese plant (Monstera), cast iron plant (Aspidistra elatior), dumbcane (Dieffenbachia), peperomia (Peperomia), arrowhead vine (Syngonium podophyllum), inch plant (Tradescantia, Zebrina), maiden hair fern (Adiantum), holly fern, (Cyrtomium falcatum), spider plant (Chlorophytum comosum), Swedish ivy (Plectranthus), aluminum plant (Pilea) and snake plant (Dracaena trifasciatasyn. Sansevieria).

Posted by on Apr 25 2022. Filed under Clubs and Organizations, News. You can follow any responses to this entry through the RSS 2.0. Both comments and pings are currently closed.

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