The publication "Sustainable Trees and Shrubs," a 48-page document containing a list of sustainable plants, including drawings and comprehensive indices, is available in PDF format or may be purchased from the URI Cooperative Extension Education Center by calling (401) 874-2900.

Download Sustainable Trees & Shrubs List in PDF Format

http://www.uri.edu/research/sustland/

An Introduction to the Sustainable Plant List:

Plant lists are invaluable resources for garden enthusiasts, designers, nursery trades people and landscape architects. We constantly consult books and nursery catalogs which list landscape plants, especially those that organize plants by their characteristics and landscape uses. As times and fashions change, new plants emerge, old plants are rediscovered, and others lose favor and disappear from these lists. But one point remains clear: listing plants encourages their widespread distribution and use. The purpose of this publication is to encourage the production and use of landscape plants that are more sustainable: those which are not invasive and require reduced inputs of pesticides, water and maintenance.

Why Sustainable?

Not long ago, plants from around the world could be introduced into the landscape and provided with the care needed to ensure their long-term beauty and success. Pesticide use was widespread and its effectiveness unquestioned, labor for intensive care was available and affordable, and the supply of natural resources was considered limitless. Much has changed in recent decades; we have become painfully aware of the limits of our natural resources and the precarious balance of nature in which we play a pivotal role. Many in our society are looking for ways to reduce human impacts on the environment. Others lack the time or resources to manage pests or maintain shrubs that require frequent pruning or irrigation. These people should find the sustainable plant list an invaluable resource.

Careful plant selection is the key first step in developing a balanced and self-perpetuating landscape. However, plant survival with minimal maintenance is not the only issue in sustainability. We are having more difficulty with invasive exotic plants which have escaped from managed land-scapes, displacing native plants and disrupting natural ecosystems. The use of these potential invasives cannot be seen as sustainable except in very controlled situations.

This list of sustainable plants is not offered as the entire answer. Proper siting, planting and maintenance are necessary for a plant to prosper in the landscape. Therefore, climatic conditions, exposure to sun and wind, subsurface soil and moisture conditions, etc. must be considered when selecting plants for a particular location. Sustainable or not, if one ignores the site and a plant's cultural requirements, that plant will suffer.

A List for Professionals

In preparing this list and the accompanying plant descriptions, we have targeted a professional audience, with an expectation that through time, as these plants become more available, this information will filter down to the consumers. Plants on this list are proven performers in Southern New England (USDA Hardiness Zones 7a - 5b), and many of them can be grown both north and south of here (although the pest complexes might change). This list is dynamic and will continue to change as new plants and pests are introduced and as we learn more about existing ones.

The list is only a guide. Plants are included which have qualities appealing to designers and plant lovers alike. Plant descriptions include color, form, texture and growth habits as well as maintenance requirements and hardiness. Many of the plants on the list are well known and currently in production, while others need to be grown and distributed more. We are well aware that it will take a decade or more before some of the newer plants are readily available in the trade.

Many of our favorite plants are not on the list, because serious pests threaten their existence or their maintenance requirements are too high for them to be considered sustainable. That doesn't mean that we won't include a few of them in our landscapes. Life would be indeed dull without a rose, but most of us would not want to maintain a half-acre of them. Plants with occasional pest problems or those with relatively minor problems are included on the list with cautionary notes. It is only those plants with life-threatening or chronic pest problems that are omitted from the list, along with seriously invasive species. The list is not intended to eliminate the production of high maintenance plants with desirable traits. Instead, it is intended to encourage the broader distribution of plants which seem to be better suited to satisfying not only our horticultural requirements, but also our environmental concerns.

Native Plants

There is renewed interest in native plants (those found growing outside of cultivation in this region during pre-Colonial times) which often are better acclimated, less pest prone and more favorable for native wildlife than exotic plants. Native plants are identified in Appendix 2. However, it should be noted that many exotic insect and disease pests have been introduced in the past 300 years. They have virtually eliminated some of our native plants and become serious pests of others. In these cases, it is useful to look to other parts of the world where plants have evolved resistance to these pests. Even without introduced pests, some native plants have problems in our landscapes where they are far removed from their natural environments. A fabulous forest shrub can have serious difficulties when sited between a driveway and a sidewalk. It is likely that a sustainable landscape will feature many native plants, but we think there are many non-natives which should be considered as well.