For over forty years Ralph Snodsmith of the Garden Hotline radio show uttered the phrase "a 50¢ plant for a $5 Hole".  As a longtime horticultural extension agent this was his philosophy for planting trees and shrubs and just about every other plant in the garden.  I had the distinct pleasure of studying with him in New York City at the Botanical Gardens.

Here are his 9 factors to consider when planting..

What is the function of the plant? To provide shade? If so, what kind of shade? dense or filtered, summer or year-round? If used for screening, is it for summer screening?, If so, a deciduous screen - one that drops foliage during winter -may do.  If the plant is for year round screening in a NYC landscape design, choose an evergreen.

Is the plant hardy in your area?  Review the USDA hardiness Zone map.  It is important to identify your location, compare your zone to that of the species and variety you want to plant. (As an addendum to Ralph's words, consider that these maps have changed 3x in the last 15 years.. consider global warming.)

How long does the plant live? Longevity is relative.

How fast does it grow? How long will it take to produce the desired effect?  A 10ft tall Willow tree in ten years can reach 50 feet tall with a 50ft. spread, while an Oak tree may struggle to reach 20 ft tall in the same amount of time.

Is the plant relatively pest free? Spend time researching the benefits and challenges about a plant. Lilac shrubs come down with powdery mildew, scale and borers.  Roses are confronted with aphids, japanese beetles, blackspot and mildew.  The only plant claimed to be pest-free is the Gingko. 

What are the maintenance requirements of the plant? Does the plant need constant pruning?  What are its irrigation needs. Fertilization needs?

What is the preferred culture of the plant? What are the light needs of the plant?  Where does it typically grow in the wild?  If grasses typically grow in full sun they can do fine on a roof garden if irrigated properly. In vertical landscape design a plant will have to deal with high winds, dessication and full sun. This is somewhat similar to plants that grow near a beach such as Myrica pennsylvanica.

Japanese maples, Flowering dogwoods, Magnolias are all trees that grow well  in shady front gardens of Brooklyn Brownstone gardens.  Brooklyn garden design typically require part shade trees, or trees that are understory trees. Remember to consider the other plants around it in your landscape design.

Are there mitigating factors? Is it in a high traffic area? Are there four legged creatures around? Dogs, cats, squirrels, voles, deer, etc. can have a major effect on the success of the plant your choose.

But most importantly, consider what type of soil the plant in question performs best in.  Want blueberries? Azaleas? These are ericaceous plants.. they want acidic soil.  Cornus sericea will grow best in moist soil.  

**adapted from Ralph Snodsmith's "New York Gardener's Guide"