Folks often ASK THE WIZARD some questions about landscaping with native
plants:
Q: What is a native plant?
A: For the purposes of the materials on this Internet web site, native
plants are defined as all species indigenous to, or that originated in,
a region at the time of European settlement. We are looking back and using
this pre-European settlement snapshot as a model upon which to base our
efforts to restore or replenish the land.
Q: I have heard that I should only buy plants or seeds which originated
from my local area. Is this true?
A: Another way to phrase this question is "how native is native"? Though
a particular species of plant may exist in prairies in both Iowa and Illinois,
over time that species adapted in slightly different ways, adjusting to
the different conditions in each of those areas. Utilizing plants which
originated in a local area builds upon this unique adaptation, and is geared
toward maintaining the integrity of the local gene-pool.
"How native is native", or how far away can a plant or seed come from
and still be considered native to a local area, is a tough question. There
is a range of opinions about what the answer should be.
One line of thought is that plants and seeds introduced or planted in
an area need to come from very close to the area being planted. For instance,
the North Branch Prairie Project in the Chicago area requires that the
seeds used in prairie restoration originate from native plants within 15
miles of the restoration site.
Others believe that it is important to look at how each particular plant
species naturally spreads their seeds. Following this reasoning, if a plant's
seeds are naturally disbursed through the wind, plant/seed sources from
a relatively wide geographic range are acceptable. If the plant's seeds
are eaten and then deposited by animals with a limited range, sources for
the plants/seeds would need to originate from a closer geographic area.
Still others believe that as long as the native variation species originated
in a specific type of ecosystem (e.g. prairie), the genetic variation is
inconsequential. In their opinion, it is appropriate to use the plant/seeds
in other similar ecosystems no matter where the geographic location.
Most of these "how native is native" seed source issues have surfaced
around designing the restoration work for degraded natural areas. And while
the scale for restoring ecosystems and planting wild gardens is certainly
different, there are many similarities. Both are improving the environment.
For a gardening setting, you need to decide, as steward of your land, where
you lie along this spectrum of opinions. As a practical matter, you may
find that there are not enough local seed sources to fill the demand from
gardeners looking for native seeds. Whatever you decide, it is important
to note that by planting native plants you will be providing a variety
of vegetation for birds, butterflies and beneficial insects to find food
and shelter in. As a rule of thumb, buy plants or seeds from garden centers
or nurseries with seed sources that originated as close as possible to
the area where you want to plant them.
Q: Should the native plants be raised in nurseries? Can they come directly
from natural areas?
A: As important as it is to use plant stock from your local area, it is
important that the native plants and seeds themselves do not come directly
from the natural areas. Poaching of plants and seeds from wild areas will
eventually deplete these areas of the seed stock they need to be self sustaining.
Responsible nurseries and garden centers raise the native plants themselves,
or otherwise ensure that the plants that they sell were not stolen from
the wild. Often nurseries will receive seed stock from the stewards of
natural areas. Plants from this wild seed are crossed with the nursery
plants of the same species to ensure that the native plants sold remain
strong and hardy. Many of these reinvigorated plants are returned to the
natural areas where they originated. Others are sold for native landscaping.
Q: If I'm not going to use fire to maintain the native plants in my
back yard, can I still use native plants in my landscaping?
A: Controlled burns are used to maintain prairies in natural areas. The
fire serves to burn away all of the vegetative materials so that the bare
soil can be directly warmed by the sun. Since it is not appropriate to
set fire next to building structures or in enclosed garden settings, mowing
your native landscaping will perform the same function as the burning.
By mowing down your native landscaping in early spring, and removing the
debris from the area, the exposed soil will be warmed by the sun, and thus
mimic the natural fire cycle. Mowing can be done every spring, or you can
rotate by mowing portions of your yard in the fall, or letting portions
grow untouched for a few seasons. Each technique favors different plants,
and thus encourages a variety of plants to emerge. Contact your local garden
center, nursery, or other experts with experience in native plantings for
specific suggestions appropriate for your yard.
Q: If I only want to use some native plants in my landscaping, are there
certain non-native plants which I should be wary of?
A: Yes. A number of non-native exotic plants have become problems in our
natural areas. To help slow the spread of these species, you should try
to avoid their use. Some of these plants may start in flower gardens and
spread to natural areas. They often squeeze out the diverse native vegetation,
and do not provide the cover or food for wildlife. An example is purple
loosestrife, which has invaded many of our wetlands, has little value for
our wildlife. Some states have declared some of these plants as noxious
weeds, and their sale is prohibited. However, such laws are usually enacted
after the plant has already become a serious problem. Because it is difficult
to list all the plants that should be avoided, you should contact your
state natural resource agency or local conservation groups before purchasing
plants. Better yet, just stick with the natives!
Q: What is meant by 'restoring an ecosystem'?
A: When restoring an ecosystem, we help the land to regain the balance
of native plants that were originally found on the site prior to European
settlement. With restoration, we are not expecting everything to be exactly
as it was 150 years ago since we don't have all of the pieces. By removing
exotic plants that have moved in and sometimes taken over an area, we allow
for the conditions that let the variety of native plants, and the birds
and animals which depend on them, flourish in balance. Once restored and
properly maintained, the diverse web of plants and animals will remain
stable for generations to come.
Q: What is the difference between using native plants in my garden and
restoring an ecosystem?
A: Restoration work involves working with the seed bank in the soil of
natural areas or replenishing that seed bank with native plants in order
to reestablish the original functioning ecosystem - the web of life. Through
restoration work degraded areas will return to the self sustaining areas
that they were.
Garden situations are different. The soil in residential areas is often
imported from else where, or so disturbed that it no longer contains the
seed memory which it originally held. Though it is not possible to recreate
the complex ecosystem which originally inhabited the area where your garden
now stands, planting native plants will help improve the environment. For
instance, by planting certain native flowers, you will signal to the birds
and butterflies to return to the area. Also, since the native plants had
originally adapted to the soil and climate conditions in your area they
will be very hardy and tolerate heat and drought well.
Q: What is biodiversity? Why is it important?
A: Biodiversity, also called "biological diversity" or "ecological diversity",
refers to the variety of life on earth. Biodiversity is often looked at
on three levels - the ecosystem level, the species level, and the genetic
level. An ecosystem includes all the plants and animals in an area, together
with their physical-chemical environment. Examples of ecosystems include
prairies, forests, and wetlands. In each ecosystem there are populations
of individual species, such as purple coneflowers. These individual species
are only found in specific types of ecosystems. At a genetic level, the
gene pool found within groups of purple coneflowers in different geographic
regions vary slightly because they have adapted to the different environmental
conditions.
In order to be healthy and sustainable, an ecosystem needs to be filled
with a wide array of plants and animals indigenous to the area. In addition
to providing food and shelter to birds and animals, a healthy ecosystem
provides many services to society. For instance, a healthy forest ecosystem
can prevent soil erosion, reduce flooding, detoxify chemicals in air and
water, improve the local climate, and sequester carbon that would otherwise
contribute to global climate change. Also, the genetic material in wild
plants and animals may have great potential value in medicine and industry.
Q: What is the difference between natural landscaping, native landscaping,
and beneficial landscaping?
A: These terms are used somewhat interchangeably. For the purposes of this
Internet homepage, we are defining the terms as follows.
Native landscaping refers to the use of plants - for example, prairie
grasses, woodland and wetland plants - that flourished here prior to occupation
of the region by settlers from eastern North America and Europe.
Natural landscaping implies the use of native plants but has slightly
broader implications because it also suggests landscaping to give the "look"
of the landscape that existed before the mid-1800s." With natural landscaping
native plants will be used; there may also be an attempt to restore or
reconstruct the landscape to look and function more as it did prior to
settlement.
Beneficial landscaping applies to a whole array of landscaping techniques
that help retain natural landscape features of the undeveloped site (including
wetlands, woodlands, and natural drainage features), reduce the need for
pesticides and fertilizers, reduce the heating and cooling needs for buildings
(shading, windbreaks), and reduce the need for internal combustion engines
to drive landscape maintenance equipment. It also includes designing the
site to incorporate natural drainage approaches such as swales and vegetated
"filter strips" in contrast to storm sewers and artificial drainage channels.
Both native and natural landscaping fit into this category.
These terms are relatively new. It can be expected that their definitions
will be fluid. None of these definitional problems should obscure the basic
concepts. (Refer to the Tool Kit for Local Governments.)
Q: Will native plants attract rats?
A: No. Actually, natural vegetation does not provide the sort of food in
quantities required to sustain a population of vermin. Some small mammals
like mice, gophers and moles live in grassy areas, but do not pose a health
threat. You may want to leave a mowed strip of two to three feet around
your house as the weather turns cold to discourage mice from having easy
access to your home. Moles and gophers do not enter homes.
Q: Will native plants encourage fire?
A: Fires, or prescribed burns, are necessary to maintain natural prairie
systems. In areas where burning is not practicable, such as in an urban
garden or next to buildings, mowing will serve the same maintenance function
as fires. By mowing and removing the plant debris from the site in the
early spring, you will expose the soil to the sun's warming rays and thus
promote growth of the native plants. An interesting fact about fires: Plant
fires, such as prescribed burns, can only sustain high heat for about 20
seconds. In order to ignite wood and sustain a fire that could damage a
home, the fire would have to burn within four feet of the structure for
seven and-a-half minutes.
Q: Will native plants attract or allow mosquitos to breed?
A: No. In fact natural landscapes (other than recreated wetlands) discourage
the pools of standing water that are required for mosquitos to breed. Mosquitos
require 10 days of standing water to complete their life cycle.
Q: Will native plants increase the pollen and my allergies?
A: Probably not. While there are few native plants that give off the allergic-type
of pollens, most of the native plants are insect pollinated, not air pollinated.
It is the pollen in the air that triggers allergic reactions. The plants
responsible for most pollen allergens are not native to the Great Lakes
such as, ragweeds (Ambrosia spp.), pigweeds (Amaranthus spp.), a few species
of goosefoot (Chenopodium), and unmown nonindigenous turf and pasture grasses
such as Kentucky bluegrass, Bermuda, orchard grass, redtop, and timothy.
Information based on: 1. The Wild Lawn Handbook: Alternatives
to the Traditional Front Lawn. Written by Stevie Daniels. 2. Wild Ones:
Natural Landscapers, Ltd.
Created June 20, 1996
Revised January 17, 1997
URL - http://www.epa.gov/greenacres/ga-q&a.html
Please contact Danielle
Green, U.S. EPA GLNPO with your comments.