I hear people talking about common milkweed as invasive. Can native plants be invasive?
Answer:
No
matter where I travel throughout the U.S., I often hear people talk
about certain native plants as “invasive” perhaps mentioning plants like
Canada Goldenrod (Solidago canadensis) or Common Milkweed (Asclepias syriaca) – two plants that can spread extensively by rhizomes and create large stands.
Hmmmm,
aren’t those great ecological plants? They certainly are! An
extraordinarily large number and variety of pollinators visit these
plants and many species of birds eat their seeds. Canada Goldenrod
blooms in the fall, a time of year when resources are slim for
pollinators. Common Milkweed is the preferred species of milkweed used
by Monarch butterflies as a host plant for their caterpillars. So, are
they invasive? Not at all.
Canada Goldenrod (Solidago canadensis) photo by Peter O’Connor_Flickr
Some
indigenous (aka native) plants are certainly more aggressive than
others, but that does not make them invasive. Sometimes aggressive
native plants are exactly what you need to replace and outcompete truly
invasive plants that have been introduced from other ecosystems.
Japanese Knotweed, Black Swallowwort, Autumn Olive, to name a few – are
some of the bad boy invasives that terrorize landscapes in the
Northeast. If you were to remove a patch of Japanese Knotweed,
replacing it with native plants, then you’d better bring out the big
guns that have a prayer of standing up to that Godzilla of invasive
plants.
Would you ever use aggressive native plants in an average
garden setting? You certainly might, siting these “friskier” natives
appropriately, where they have ample space and/or ample competition. Or,
you might select similar species that are more subdued – perhaps Asclepias purpurascens (Purple Milkweed) in lieu of Asclepias syriaca (Common Milkweed). “Put the right plant in right place” still rings true.
So
what are invasive plants anyway? Ask 10 people, get 10 different
answers. In 2006, the National Invasive Species Council and the Invasive
Species Advisory Committee adopted the following definition: “a
species that is non-native to the ecosystem under consideration and
whose introduction causes or is likely to cause economic or
environmental harm or harm to human health.”
Silphium perfoliatum Photo by Rockerboo_Flickr
To
make things even more confusing, some states are including indigenous
plants on their “noxious weed” and prohibited plant lists. It is
confusing. New York State, includes Silphium perfoliatum (Cup
Plant) on its list of “Prohibited and Regulated Invasive Plants.” Yes,
it’s frisky, but it is native to New York, and has great ecological
value. Not only is Cup Plant highly attractive to pollinators, its
leaves are attached to the stem in such a way that a small “cup” is
formed, capturing rainwater, and attracting thirsty birds and insects.
Noxious weed or valuable native plant? Like, I said, it’s confusing.
Cup Plant Holding Water for Birds (photo by Benet 2006_Flickr)
Let’s flip the initial question and ponder – “can invasive non-natives be ecologically beneficial?”
This
question is even trickier. I have heard from more than one beekeeper
that Japanese Knotweed is a great nectar plant. Honey bees (non-native,
albeit valuable to man for the surplus honey they produce) flock to
Japanese Knotweed. As noted above, Japanese Knotweed (Polygonatum cuspidatum)
is a beast, swallowing any plant within its grasp, and not stopping
there, but continuing its mighty reach until a massive monoculture
results. Surely, we can make the argument that in spite of its nectar,
this is a plant that should be removed, as it presents environmental
harm.
The takeaway here – use regionally appropriate, site
appropriate native plants, understanding that some a bit more boisterous
than others – and that can sometimes be exactly what you need.
Thanks for your question!
From Kim Eierman at EcoBeneficial!
Photo: Cup Plant (Silphium perfoliatum) with a happy native bee.
( Saw this on FB (thanks to Les Squires, Transition in Action), thought of Jack. Not just for vegetables, good for shaping rain gardens. And the steep ones would be great for arthritic gardeners.)
Hugelkultur
are no-dig raised beds with a difference. They hold moisture, build
fertility, maximise surface volume and are great spaces for growing
fruit, vegetables and herbs.
Hugelkultur, pronounced Hoo-gul-culture, means hill culture or hill mound.
Instead of putting branches, leaves and grass clippings in bags by
the curbside for the bin men... build a hugel bed. Simply mound logs,
branches, leaves, grass clippings, straw, cardboard, petroleum-free
newspaper, manure, compost or whatever other biomass you have available,
top with soil and plant your veggies.
The advantages of a hugel bed are many, including:
The gradual decay of wood is a consistent source of long-term
nutrients for the plants. A large bed might give out a constant supply
of nutrients for 20 years (or even longer if you use only hardwoods).
The composting wood also generates heat which should extend the growing
season.
Soil aeration increases as those branches and logs break down... meaning the bed will be no till, long term.
The logs and branches act like a sponge. Rainwater is stored and then
released during drier times. Actually you may never need to water your
hugel bed again after the first year (except during long term droughts).
Sequester carbon into the soil.
On a sod lawn Sepp Holzer
(hugelkultur expert) recommends cutting out the sod, digging a one foot
deep trench and filling the trench with logs and branches. Then cover
the logs with the upside down turf. On top of the turf add grass
clippings, seaweed, compost, aged manure, straw, green leaves, mulch,
etc... Hugel bed in Ontario, Canada (By Travis Philip) Hugelkulter from permies.com: Pallets used around periphery Steeped raised beds: From 'Sepp Holzer's Permaculture' Sepp Holzer recommends steep hugel beds to avoid
compaction from increased pressure over time. Steep beds mean more
surface area in your garden for plants and the height makes easy
harvesting. The greater the mass, the greater the water-retention
benefits. Vertical logs Hugel bed dug in clay with logs put in vertically,
next branches and lots of wood chips. Top 6" will be wood chips and
dirt. This bed will store water and give nutrients for many years to
come. Straw bale gardens require less soil, less water
and hold heat. As the straw breaks down nutrients feed the plants.
Combining a straw surround with a hugel interior, topped by lasagne
layering is an excellent idea for an area with poor quality soil. Hugel bed in Ontario, Canada (June 28) by Tim Burrows. Tim surrounded his very tall hugel bed in pallets! Sheet mulching (lasagne
gardening) is like composting in place. Above: just a suggestion as to
sheet mulching layers. Nitrogen-rich material such as fresh grass
clippings or green leaves put right on the hugelkultur wood would help
jump start the composting process. Could also include seaweed, straw,
dead leaves, leaf mould, etc...
The first year of
break down means the wood (and fungi) steal a lot of the nitrogen out of
the surrounding environment, so adding nitrogen during the first year
or planting crops that add nitrogen to the soil (like legumes) or
planting species with minimal nitrogen requirements is necessary, unless
there is plenty of organic material on top of the wood. After the wood
absorbs nitrogen to its fill, the wood will start to break down and
start to give nitrogen back in the process. In the end you will be left
with a beautiful bed of nutrient rich soil. Tree types that work well in hugelkultur:
Hardwoods
break down slowly and therefore your hugel bed will last longer, hold
water for more years and add nutrients for more years. But softwoods are
acceptable as well, a softwood bed will just disintegrate quicker.
Mixing woods with softwoods and branches on top, to give off nutrients
first, and hardwoods on bottom, sounds like a plan if you have access to
multiple types of wood. Yet the newly decomposing softwoods at top will
eat up a lot of nitrogen at first, so compensate for that.
Woods that work best: Alders, apple, aspen, birch, cottonwood, maple, oak, poplar, willow (make sure it is dead or it will sprout).
Trees types that work okay: Black
cherry (use only rotted), camphor wood (well aged), cedar/juniper/yew
(anti-microbial/anti-fungal, so use only at very bottom or unless
already well aged. Cedar should be broken down before new plant roots
reach it), eucalyptus (slightly anti-microbial), osage
orange (exceptionally resistant to decay), Pacific yew (exceptionally
resistant to decay), pine/fir/spruce (tannins and sap), red mulberry
(exceptionally resistant to decay).
Tree types to avoid: Black
locust (will not decompose), black walnut (juglone toxin), old growth
redwood (heartwood will not decompose and redwood compost can prevent
seed germination). This article was cross-posted from www.inspirationgreen.com/hugelkultur.html
Further resources
Want to learn more about huglekultur beds? We highly recommend Sepp Holzer's Permaculture, a ground breaking book that will teach you all you need to know! (Also available as an eBook) (For US readers, you can buy from Chelsea Green HERE) Desert or Paradise by Sepp Holzer
People often have the illusion that gardens are static places,
manicured and perfect, stable and constant. Some botanical and public
gardens contribute to this idea, but they are highly stylized examples,
with legions of workers and volunteers — which most of us don’t have
access to. What can we do to maintain an aesthetically pleasing
landscape year-round that’s also sustainable and a wildlife haven?
1. Begin with design planning. You know how asters
tend to get leggy? That’s the chrysanthemum lace bug at work, and
there’s not much you can do about it. What you don’t want to do is put
those asters in the front of a border or near a path where everyone can
see their bare, brown decaying bottoms. Underplanting with sedges (Carex spp.), grasses or other low-growing perennials is what you’ve got to do.
There’s black-eyed Susan (Rudbeckia hirta),
a biennial and sometimes a triennial. But in late summer, if it’s near
the end of its life, it’ll just go brown and die. It needs to be
surrounded by other plants, especially plants that come online in late
summer — say, sideoats grama (Bouteloua curtipendula), little bluestem (Schizachyrium scoparium) or aromatic aster (Symphyotrichum oblongifolium).
Some
taller plants flop in a lush garden setting, so buttress them with
other medium-high to tall plants. Think about and design for the issues
that will come up down the road, and when you design your garden, those
issues won’t make the garden appear worn, spent or generally
unattractive.
2. Redefine attractive. There’s
growing awareness in landscape design of the value and beauty of seed
heads, sedges, dried grasses and woody stems. For a long time, gardeners
have been cutting down plants in autumn to maintain a neat or tidy
look, but then you have to look at a moonscape for several months — not
to mention the wildlife habitat you’ve eradicated for overwintering
insects and birds seeking shelter.
Designing not just with
winter in mind but intentionally for the winter garden season creates a
landscape that’s full of intention and resonates with power for anyone
experiencing it. Those rudbeckias that die back? Boy, do they have stunning jet-black seed heads. Indian grass
is an upright stunner that maintains its flamboyant tops into spring. A
“dead” garden can be as beautiful as one flush with Crayola color just
months before.
3. Use self-seeding as a jackpot and a scourge.
I don’t know about you, but I find it helpful to let the plants tell me
where they like to grow. Sometimes I’ll place something in a spot my
research suggests is ideal, but then I find that it struggles or slowly
moves — by roots or seeding — to a better spot where it thrives. This is
not a defeat for a gardener wishing to maintain a cohesive and
presentable, aesthetically pleasing landscape; it is a wonderful
opportunity to engage with plants on their level.
Let some of
your less architectural or anchor plants find their way around your
garden. If seedlings pop up where you can’t stand them, toss them, move
them or give them to your friends.
4. Let shrubs take up the perennial slack in spring. The
spring cut-down exposes soil to light, which is necessary for new
seedlings and awakens the dormant ones. It also exposes a naked design. I
find spring the ugliest time in many of my landscaped areas, even if it
doesn’t last but a month. There are two strategies to fix this: Go
crazy with spring ephemerals and other early-blooming perennials, or
think about adding flowering shrubs and small trees.
When my
perennials are a foot tall at best, and the grasses are another month
away from rocketing into the air, serviceberries, plums, chokeberries,
ninebark, spicebush and viburnum carry the midspring weight — and not
just because of their blooms. These shrubs add architectural structure
and a vertical stretch of green that gives the garden the appearance of
being further along than it is. A bonus is that they help the winter
garden look good, too.
5. Celebrate the hard realities of life. Plants
are a lot like us: They get sick, they get stressed and tired, they get
lonely or overcrowded, and sometimes they just give up. I want to see
us celebrate the realities of plants and gardens — the occasional broken
stem, the monarda covered in mildew and the plants gone dormant too
early in an unusually dry summer. When we embrace the realities of the
natural world and stop fighting them with added watering or chemical
inputs, we might find the garden an intrinsically more beautiful and
inspiring place.
These are just a few ideas for how to maintain a
healthy and vibrant-looking native plant garden over the seasons. What
binds all of these strategies together is the principle of planting
thickly and in communities of plants that are also found together in the
wild. The benefits they give one another — often intangible and unseen
to us — help them thrive and also provide an aesthetic that never
falters or calls into question the skill or vision of the gardener.
A widow skimmer enjoys the perimeter of a new native rose garden.How’s a person supposed to get any work done when such exquisite creatures are flying in front of her face all day? That’s
the question I’ve posed to the birds and bees and butterflies doing
their best to distract me from a book project this summer. They’ve
remained conspicuously silent on the matter, but my sister has confirmed
my suspicions about this winged conspiracy: “There are so many,” she
said of the pollinators crowding the swamp milkweed and green coneflower
near my patio, “it’s hard to look away!”
Although my blog writing has become more sporadic in light
of the looming deadline, I can’t let this week—the one-year anniversary
of the launch of Humane Gardener—go by without paying homage to all
creatures great and small who’ve made it possible. With gratitude to
them and to the many wonderful members of our two-legged species I’ve
met along the way, I offer these tips.
Step 1. Make Friends.
Dozens
of great spangled fritillary butterflies make their home in my yard
every day. Though they enjoy butterflyweed and other plants in the
milkweed family as adults, their caterpillars must have violets to
survive.
You don’t need to earn a landscaping degree or hold a PhD in bee
biology to start a wildlife garden. But it helps to have people in your
life who are willing to share with wild abandon.
If it weren’t for my friend Sally, we would not have such a
proliferation of fritillary butterflies. Though they’re attracted as
adults to the nectar of many native species, they can lay their eggs
only on violets. From the three Sally uprooted 15 years ago, we now have
thousands that provide essential habitat for these little beauties.
At only two weeks old, our newest milkweed patch is much younger than
Sally’s violets. But I’ve already found monarch eggs on each of the
seven little transplants. And that’s thanks to Molly, who generously
offered up her extras at a time when my battered milkweed in the front
yard seemed to be getting too tired to support fall migrations. My
latest milkweed patch is sited near a pollinator garden, where last
night I spotted a monarch butterfly among all the swallowtails,
fritillaries, skippers, wasps, and bees. Wondering if she’d laid eggs on
the transplants, I went to look under the leaves. Sure enough, some
even had two eggs. Given to me by a new friend, these plants will
heretofore be known as Molly’s Magic Milkweed.
My gardens are filled with such gifts: the aptly named “queen of the
prairie” flower from Lisa, the tasty strawberries from Janet, the
sweet-smelling mountain mint from Stephanie, the exotic-looking native
hibiscus from Jan, the misunderstood but much-beloved-by-pollinators
dogbane from Angela, the giant late-flowering asters from Christine.
Whenever I see all these plants and the life they sustain, I am
grateful for the friends who care so much about our earth that they want
to share its bounty.
Step 2. Give Back.
Planted
in June directly into the turfgrass, these elderberries, a great fruit
source for birds, are already twice as large as they were when I bought
them.
Preying on insecurities of new gardeners, a whole industry has grown
up around promotion of fancy bagged products and potions. But more often
than not, these external inputs are counterproductive, disrupting
natural soil cycles and maiming bees, butterfly larvae, and countless
other sensitive creatures who feed and reproduce on our plants or in the
ground.
Using what you have on hand—and returning materials back to the
earth—is more sustainable and infinitely more doable on a small budget.
On our own two acres, carving gardens out of the sea of turfgrass used
to be a daunting task. After spending too many sweltering afternoons
jumping up and down on a shovel wedged into hard clay, I began papering
it over instead. This method preserves both rich organic matter and my
fragile back. It also means I can use natural materials already on site,
as Maryland natives grown in their preferred light and moisture
conditions usually thrive in existing soil. All
grown in: This is the edge of a large garden created last year by
layering newspaper over grass. Clethra is one of many beautiful
alternatives to butterfly bush, the seeds of which escape from gardens
to invade natural habitats miles away. Native groundcovers golden
ragwort and green-and-gold serve as “green mulch” in this garden,
quickly filling in around the well-used birdbath.
While the most commonly recommended method is to layer paper or
cardboard beneath compost or mulch and let it all sit a few months
before planting, I prefer not to wait that long. To make an
insta-garden, I dig holes in the grass, put my plants in, surround them
with paper, soak the paper with water to hold it in place, and top it
all off with whatever else I have handy—leaves, old coconut fiber from
hanging pots, potting soil from transplants, and (when I run out of
options) mulch from the landfill. The beauty of this method is that,
even as the new plants grow taller and the surrounding materials start
to break down, animals and wind begin sowing seeds of other species in
the spaces between. And before I know it, the earth erupts in flowers
sown by both me and by nature.
Step 3. Think of the Children.
Spread
the word: This pearl crescent butterfly fluttered all over the
newspaper I laid down around my new milkweed, reminding me that we need
to consider the needs of all our garden visitors. Though adults can
drink nectar from many flowers, the pearl crescent needs aster leaves
for her babies.
Much attention has been paid to the plight of monarch butterflies,
and for good reason. The wanton destruction of the only plants they can
lay their eggs on—those in the milkweed family—has led to a steep
decline in their numbers. But milkweed is only one host plant among
hundreds needed to support the life cycles of many butterfly and moth
species in our gardens. If you want butterflies, you need plants that will feed their babies. Antennaria
groundcovers—in this case, Parlin’s pussytoes—are a favored host plant
for caterpillars of the American lady butterfly. Within two months of
adding them to my garden this summer, we already had an American lady
nursery.
A pearl crescent reminded me of that last week while I planted
Molly’s Magic Milkweed to expand my monarch offerings. She made quite a
show of enjoying the damp newspaper and mulch used to smother the grass
of the new garden, but her presence had broader meaning for me. This milkweed is nice and all, she seemed to be saying, but I need asters for my babies! While I
happen to have many species of aster in my garden—including heath
asters, smooth asters, and New England asters—I can’t say I planted them
intentionally for pearl crescent caterpillars. In the fall I will add
more in honor of my small-but-mighty friend.
Step 4. Call in Quality Control.
What’s
good enough for the catbirds is good enough for me. They enjoy a range
of insects and fruits in their diet, and I am only too happy to provide
for them.
Host plants for caterpillars? Check. Nectar plants for butterflies?
Check. Is there something you’re still forgetting? You can always count
on the catbird to let you know. Like many birds, and especially baby
birds, they are voracious consumers of insects. To ensure you have a
plentiful supply, stay away from pesticides and other chemicals that
kill grasshoppers and ants and everyone in between. Manufacturers of
these products like to promise you the perfect rose garden, but a garden
too toxic for a bee and too nutritionally deficient for a bird is no
garden at all. Catbird-tested,
goldfinch-approved: A year-old garden made from newspapers provides
rudbeckia and other much-needed midsummer seed for goldfinches, one of
the few birds who don’t feed their babies insects. They are “among the
strictest vegetarians in the bird world,” notes the Cornell Lab of
Ornithology.
Birds also need native fruits and seeds in varying supply when
migrating, breeding, and overwintering. Shrubs offer both berries for
sustenance and dense habit for nesting and cover from predators.
Fortunately I was able to let my catbird friend know that this
garden-in-the-making would soon be a thicket of native roses, a
family-friendly spot for rose-hip dining and baby bird rearing.
Step 5. Let the Team Take Over.
Because
our native trees, shrubs, vines, perennials, and groundcovers feed many
species of caterpillars, the bluebirds in our front yard had plenty of
food to raise noisy, healthy babies this year. Photo by Will HeinzIn the spring hummingbird moths dine on phlox divaricata; in mid-summer they find this phlox paniculata irresistible.
Once you have a few spots planted with species native to your area,
sit back and watch the magic happen. Leave as much of your garden as
possible the way nature intended: Let perennial stalks stay up
overwinter so the seedheads can feed birds and stems can shelter bees.
Provide bare, undisturbed patches near your pollinator plants
so ground-nesting bees can raise their babies. Let leaves fall where
they may to give shelter to caterpillars, pupae, salamanders, and many
other animals during the cold, dark days.
You’ll be amazed by how many furred, feathered, and antennaed
friends swoop in to offer their help once you make your home theirs,
too.
I hear people talking about common milkweed as invasive. Can native plants be invasive?
