I discovered mold on many of my jade plant's
lower leaves about two weeks ago. I have been picking
off several new moldy leaves each day. I haven't watered it since it came
in the house in early October and the soil is very dry. Because of
all the rain we had in the fall I was covering it with a thin plastic table
cloth when it rained, but the soil was pretty wet when I brought it
in. It is on a stand in front of a sliding door which is on the
east side of the house. Would some artificial light help? If
so could I use a light bulb on an unshaded floor lamp? How about a
fungicide? - D -
Light will always help a jade (Crassula species). Use a
fluorescent fixture or bulb. If an incandescent bulb is all you
have, use it, but it won't be so much help as a fluorescent bulb
since it has to be further away (see Plants and Artificial Light,
below) to avoid cooking the plant.
White's all right if the leaf's firm
About the moldy leaves: It's a great that you noticed them right
away, and are picking them off as you see them. If they're still
pretty firm in feel and the white coating is one you can rub off
(photo above), that's probably powdery mildew. It should be enough
to remove infected leaves and give the plant better light and air
on its remaining leaves -- thinning its foliage is one way to do
If the moldy leaves are more gray than white, and soft to mushy,
the plant may have a Botrytis infection. Gray
mold/Botrytis is more serious than mildew so you may lose
more of the plant before it's beaten. However, it's an ailment that
responds to the same controls -- cleanliness and giving the plant
the light energy it needs to regroup.
Fungicide: Doesn't release you from
other control measures
About fungicide: We wouldn't. It might help against mildew or
Botrytis but using it will not excuse you from doing all
the rest, because all it can do is prevent new infection. It won't
cure what's already within the plant's stems and leaves. The "mold"
we see is the mature, reproductive face of the fungus. The fungus
has been in residence for some time when we see that.
You can learn about watering succulents from some of the
photos included here, and also something about the value of saying,
"Let's go see": We dropped in on friends with jades, looking for
mildew. We found it on a few leaves of a densely-leafed jade
sitting on a shelf in a conservatory against the solid back wall.
"Oh, look at you!" Its gardener said, "You were fine while it was
summer but now that it's winter you can't handle that stuffy shelf,
can you?" Then she moved the plant from its place against the wall,
out to a place where light and air will flow all around
Looking at the jade on the shelf from straight on (blue
arrow), we bet you can't tell the air flow there is compromised.
But look again from the side (shown below) and see the giant monkey
paw plants blocking air and light from the side.
Jades under cover of plastic: Not happy campers!
We understand your concern about a jade being too wet outdoors,
but next year don't cover it in plastic. As water moves into the
root zone from adjacent soil -- something you can't stop -- the
earth begins to exhale humid air. Then, plastic can trap lots of
moisture around the foliage. Unless you're there to remove the
sheet the minute the rain stops, fungus will have more hours of
dampness and thus more chance to take hold than it would have
It's enough to make sure the ground or potting mix around the
roots drains perfectly. Even though the plants can survive long dry
spells, they do handle rain in the wild. Our jades -- our own and
those of clients -- are out in the weather all summer, planted in
coarse builder's sand in pots with clear drain holes, or in that
same sand in-ground in spots where excess water can fall quickly
through and below the garden soil.
Plants and artificial light: Make it cozy!
Light's energy level drops drastically with distance -- move a
plant two feet from a light source and it loses 75% of the
It may also lose its friends -- Olive, here in our jade, was not
only enjoying sitting in an elevated perch, but basking in the
light we keep shining on the tree!
Fat leaves tell tales!
When you see that a plant's leaves can swell and hold water, as
many succulents do, you might think "Keep this plant dry. You're
right -- part of the time! Leaves that hold water are an indication
that at least some time during the year in its native clime, that
plant has plenty of water available, can handle that and store it
as a hedge against drier times.
It's simple to judge a leaf's turgidity by feel. A little
tougher to learn here, by eye. Yet you should be able to tell that
the leaf on the left is more plump, the one on the right thinner --
not thin enough to need water, however. That's where touch comes
into play, when the leaf is thin and has also lost its firm
Plants staying healthy: Thinner during winter
Don't worry too much over leaf loss when you bring plants
indoors for winter. Many plants thin themselves by half, or more,
as an adjustment to lower light inside. Some do this drastically,
some more gradually.
Watering a succulent plant during
In winter, when days are short so jades are resting, don't water
until the individual leaves begin to get thin. If the leaves look
plump and feel firm, hold off watering even if the soil is really
dry. None of the leaves shown here are thin enough to be
thirsty -- when their time comes they may even show wrinkles at
their thinnest. The gardener must develop a feel for that
condition, in order to give the roots the dry, airy rest that keeps
Our jades' root balls are bone dry in winter more often than
they're moist. Yet the leaves remain turgid -- plump -- so we leave
them alone. Those inside our house may need water only twice in all
of winter, before they resume growth in March's growing light.
Those wintering in a friend's dark, cool
will probably go the whole winter without water.
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