University of Vermont Extension 
Department of Plant and Soil Science

Anytime News Article


Dr. Leonard Perry, Extension Professor
University of Vermont
Hostas, spurge (Pachysandra), and rhododendron are some of great choices you have for shady gardens.  Before choosing any plants for shade, it’s important to realize a few facts about this environmental habitat that will help you grow more plants there more successfully.

Shade is not all the same.  Soil moisture levels can vary from moist to dry.  Ferns and astilbe like moist shade and wont grow well in dry shade, while hostas and barren strawberry (Waldsteinia) will.  A wet area, water seepage from the ground, or a stream, can create a moist woodland.  Areas under large trees can be quite dry from the tree roots taking up most available soil moisture.   In my own yard, soil moisture under a large maple often begins the season around 70 percent, similar to my full sun beds away from any trees.  By midsummer, especially if little rain, the tree area can drop to 35 percent moisture, with little drop in the loamy sun beds.

Whether a plant “prefers” or merely “tolerates” a certain soil moisture is another aspect you don’t usually see mentioned.  Lungworts (Pulmonaria), for instance, prefer a moist soil but will tolerate some dryness even though they wilt.  Coralbells prefer a drier soil, but will tolerate some moisture.  The third aspect relates to soil moisture as well, that being the age of the plant.  A plant such as lungwort may not tolerate much drought when young, but may when mature. 

Of course light is the main factor with shade, and you may see various terms to describe the amount of light a plant “needs”.  As with soil moisture, the terms “prefer” and “tolerate” apply here too.  Many sun plants may tolerate some shade, just bloom less, and perhaps be more straggly and need staking.  On the other hand, some shade plants (especially in the north with cooler summers) may tolerate full sun IF sufficient soil moisture is maintained.

Here are some terms you may see referring to shade, from most dark to most light.
-- Full shade occurs when no direct sunlight reaches plants, and there isn’t much reflected light either.  This is what you find underneath dense tree canopies, such as under a large deciduous (loses its leaves in winter) maple or oak tree, or evergreen pine.
-- Summer shade is a variation of full shade, and occurs under deciduous trees that are bare in spring allowing light in, and fully leafed out in summer allowing no direct light. This is what you find in many northern mature woodlands, and favors spring wildflowers whose lives are programmed to maximize on this fleeting spring sunlight.
-- Bright shade is a term you see less often, and occurs where little direct light reaches plants but where they do get much reflected or indirect light.  This might be found next to a bright, south-facing wall of a building.  You can create bright shade by removing lower limbs of trees and shrubs, or thinning them out.  Consider this approach if you have too much dense shade.
--Dappled shade occurs when spots of light appear for a short period, then disappear as the sun moves across the sky.  It is what you find if walking in a mixed woodland.
-- Part shade occurs when direct light reaches plants for perhaps half a day, four to five hours.  This is what you find on the edges of woodlands or in front of tree plantings.  It may be afternoon or morning sun, which may make a difference with a few plants (afternoon sun being hotter).

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