have always loved Mimosas and assumed they grew from flowers until I
saw the awesome trees in southern France. I started some Mimosa
seed, and they are now about 3 feet tall and
becoming a problem to move inside for the winter. I don't think they are
hardy here in Pennsylvania, but thought I'd check just in case I could get away with
planting them in the ground if I mulch them heavily and wrap them in
for the winter. If not, I need to repot them and was wondering if
our neighbor's aged horse manure is too strong to add to the potting
mix. They have done quite well for us without any fertilizer.
If your plants are Albizia julibrissin, they will grow
outdoors in Western Pennsylvania. If they are one of several species
of mimosa, they will not be winter hardy here. Both plants are in
the pea family and commonly known as mimosa. Although Latin
names can make people trip over their tongues, these names are the only way
to know for certain that we are talking about the same plant. Albizia julibrissin is also known as
Powderpuff Tree or
Native of Asia
Silktrees are native to eastern and southern Asia. They have become
naturalized in the United States from Maryland south to Florida, and
west into eastern Texas. They do grow well in our climate but may be
killed back to the ground in severe winters. Even if a severe
winter kills them to the ground, they generally re-sprout from the
roots. Their seeds frequently germinate in the soil under the
tree or in adjacent flowerbeds, so you usually have seedlings coming
up just in case the mature tree dies.
Silktrees prefer full sun and well-drained soil but are very
tolerant of poor, infertile soil because they are in the pea family.
Such plants are known as legumes, and they have the unique
ability to fix nitrogen directly from the atmosphere. Silktrees can
be troubled by vascular wilt and mimosa webworm and are often
thought of as short-lived trees.
They are classified as an invasive alien species in areas
where they have naturalized in the United States. They spread by
sprouting from their roots as well as setting prolific seed crops.
Since they are able to grow in very poor, dry soil, silktrees
quickly colonize areas and squeeze out native plants that provide
food and shelter for wildlife. They do seed themselves in our
climate as well, but I personally have not seen them grow so
prolifically that they threaten local ecosystems. Please be aware of
their potential weedy character and grow them with care.
Close-up of Mimosa flowers
Hardiness of Mimosa
If your tree turns out to be a
mimosa, you will have to keep
it in a pot and move it into an area that does not fall below
freezing for the winter. The sensitive plant, Mimosa pudica,
is often grown in high school biology classes for students to
experiment with plant growth hormones. They grow quickly and they
hold the students' interest because their leaves close up and "wilt"
when you touch them, but they recover quickly. They can be fun to
grow as houseplants and can grow to 5 feet tall with a slightly
If you need to keep your "mimosa" in a pot, just move it up one pot
size. Moving it into a much larger container can lead to root rot
because the large volume of soil (compared to the size of the plant)
holds too much moisture for too long a time after you water. You can
use a small amount of your neighbor's aged horse manure to amend the
potting mix -- roughly one-quarter of the mix by volume. Manure can
be high in salts that can damage many plants. This is especially
true in a container where the small volume of soil cannot buffer the
salts as well as the much larger volume of soil in an outdoor
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