Please note! This and other plants in the series
have proven non-invasive in our environment and, based on our
experience, are cautiously recommended for trial by water and
bog gardeners elsewhere. Having said that however it should be
noted that anytime plants are moved to an area in which they
are not native there is a risk that they could become invasive.
For this reason they should be contained rather than set free
in the natural environment and dead heading prior to release
of seeds is recommended. It should also be noted that the fact
that they perform well in southern Ohio (zone 6) doesn't mean
that they will do so in other areas.
Just one way water gardeners can help green the planet . .
Native alternatives to invasive plants
First in the series
by Charles Leach, Ohio USA
Click images to enlarge
As part of an evaluation of plants native primarily to the
north central United States, we obtained seeds of Boltonia
decurrens (false aster), along with other seeds from Prairie
Moon Nursery. It specializes in seeds and plants of species native
to the north central United States including bog, wetland and
We tried seeds from another well known source but were disappointed
with both the selection and viability. A particularly troublesome
practice of said source, along with being stingy with the number
of seeds in their high priced packets, was sending pre-moistened
seeds that sprouted in transit and died when potted. Prairie
Moon on the other hand is extremely generous with the number
of seeds in packets that cost just $2.00 each and germination
rate is excellent. Based on customer reviews, I guess Im
not their only fan.
Having said that, it should be noted that their great variety
of seeds includes those of species that can be highly invasive
or toxic. One case is water hemlock, so buyers must research
before ordering seeds. To prevent spreading a highly invasive
species I suggest that buyers go with varieties listed as threatened
by state or federal agencies.
Boltonia decurrens (false aster) is listed as threatened
by the federal government and by the states of Illinois and Missouri
in which it is native. I planted the seeds in damp seed starting
mix in the fall, stretch-wrapped the seed flat and left it outside
over winter. Soon after being unwrapped in the spring practically
100% of the seeds germinated.
Somehow a few cells that didn't get divided and repotted got
mulched over and lost until July of the following year and were
only found when I was pulling what I thought were weeds in the
area. To my surprise I found the roots of the over 3 (1m)
tall plants confined to tiny seed cells labeled false aster,
pictured below left.
Like most wetland plants, false aster transplants well if
the soil is kept wet. As evidenced by the lost seed cells, pot
size doesn't matter a lot as long as the roots are kept damp.
I have had false asters in 6" (15cm) pots reach a height
of 6' (182cm) but, to avoid having the plants fall over, I recommend
far larger containers.
The plants on each side of the door shown below are growing
in 10" x 10" (25 cm x 25 cm) containers without drain
holes. The photograph at the left was taken in mid June. By mid
July the plants were nearly 6' (182 cm) tall and the first of
the flowers that would cover the upper branches for weeks were
opening. The second photo shows them in early August when
they were over 6' (183cm) tall and covered with flowers, as they
will be into September.
< Mid June, about 5'
Early August, over 6'
(183cm) tall and
covered with flowers >
Although happy in their drain hole free pots they suck up
about a gallon (4 liters) of water each a day. For what it's
worth they were dug out of a pathway immediately adjacent to
a where a false aster was growing in a marginal pool the year
before. So far no volunteer false asters have turned up any distance
from where they have been growing. The ones that do turn up do
not take over an area because they don't spread from rhizomes.
A word to the wise -- never turn a species that spreads by
rhizomes loose in open ground or along the edge of a natural
pond. I made the mistake of planting a Solidago graminifolia
(grass leaf goldenrod) in a bog garden a couple of years ago.
Its an attractive plant with a bamboo-like appearance but
spreads like wildfire in both wet and dry soil. We have been
trying to contain it ever since.
Foliage of false aster is attractive from early spring till winter,
although the spent flower stems die back and should be cut off,
and it covers itself with small daisy-like white flowers in late
summer. A false aster on blocks in a 24" (60cm) deep tub
kept falling off the blocks whenever the wind kicked up so I
eventually decided to let it stay on the bottom to see what would
happen. The photo below left shows it happily blooming with over
a foot (30cm) of water over the crown. It was still happy with
a skim of ice on the water in November, below center, and it
showed green leaves peaking through a couple inches of snow in
December, below right.
As it appeared that there were healthy roots on the underwater
stems I broke a couple of pieces off, potted them and brought
them into our sunroom. One died and the other survived but, now
that it is back outside, is less than a foot (30cm) tall. Don't
quite understand why it needs a period of cold weather, as it
doesn't go totally dormant, but it seems to.
With the return of warm weather I decided to repot the false
aster that wintered over at the bottom of the tub. When I removed
it I was surprised to find that it was detached from the pot
and growing happily hydroponically. The photo at the right shows
me holding the free floating plant for a portrait. After the
picture was taken the plant was put in a 12" (30cm) deep
tub along with a clump of umbrella sedge that is also growing
happily in water without soil. Sometime in the future I intend
to experiment with using both in an improvised biological filter
to remove nutrients from pool water.
Read the introduction to this series
Boltonia decurrens is a great and versatile plant that
is well worth trying in any water or bog garden in, at least,
northern areas. Having it in your garden will help insure survival
of a threatened species. How good is that?
Alternatives to Invasive Water and Bog
in WGI ONLINE