Early Fall!
Dig and dry tender tubers for next year or read and try
tricks to save them in-ground
Dear Janet,
How can I keep a tuberous begonia, caladium, some
cannas, dahlias and a dwarf palm tree from my garden for next
year?
S.T.
Dear S.T.,
Dig them now, pot up the clumps or divisions and grow them as
houseplants over winter.
Or, to hold a begonia, caladium or canna as a dormant root, cut
it back or let it be cut back by the frost, which will kill the top
but not the root. Dig it and shake off excess soil. Don't break any
big roots or nick the tuber, as fungi can enter through wounds
while it's in storage.
Invert the clump on a screen in an airy, warm place for a few
days to let the soil air dry and the tuber cure. When most of the
soil can be crumbled away from the root mass, wrap newspaper around
the soil-clad tuber and put it in a paper bag full of crumpled
newspaper. Alternatively, bury the clods in a box of clean, sharp
sand or peat.
Now, the tough part. Find a storage place that is cool and not
too dry. 50 degrees is perfect for the begonia and caladium, 45 for
the canna and dahlia, and about 50 percent humidity for all. A
Michigan basement or root cellar is ideal, but those few gardeners
who have such a space could fill it ten times over with roots that
their friends have no place to store.
As for the palm, it depends on the species. Check with the
garden center that sold it. Most species have to be kept growing
all year, frost-free. Consult a book to see if your bamboo,
banana, palm or another tender plant might be allowed to winter
outside under deep mulch, with special care.
Short reports
Overgrown shrubs and vines overwhelming
you?
Hold the shears, if you plan a significant cut-back. It is not
good to prune a woody plant while its leaves are falling. During
that time its twigs and branches harden off for winter using
compounds withdrawn from the leaves. Wait, and prune several weeks
after leaf-fall ends, or in late March or early April next
year.
Outwitting dogwood defoliators.
Liz wonders about caterpillar-like critters that are stripping
her yellowtwig dogwood. White and fuzzy at one point in their
development, the culprits are now greenish, smooth, and
striped.
Those are dogwood sawfly, Macremphytus tarsatus. They pupate
like caterpillars, but emerge not as butterflies but small flies.
These mate and lay eggs on the undersides of dogwood leaves in
June. They're common on native graystem- and redtwig dogwoods in
the fields and marshes.
Although they do little lasting damage and are only numerous
every few years, a new shrub like yours would be better off keeping
all the starches produced by its leaves toward quicker
establishment.
This sawfly overwinters in rotting wood. The larvae may already
be wandering off in search of a fallen branch or decaying wood
siding to call home. Many will be eaten by predators before next
June but some may find their way back. Reduce that chance by
placing rotting log(s) under the shrub. After the killing frosts
come, collect and burn that wood.
Put a magnifier on your wish list for the holiday
season.
Every gardener can use a hand lens or a six- to ten-power loupe
as sold at camera stores. If L.G. had looked through a magnifier at
the catalpa leaf she sent to me, there would have been no question
of what leaf spot it might be. The nature of the problem would have
leapt out so that L.G. wouldn't have thought "disease" and
"fungicide" but leaf removal and then a close watch and perhaps an
insecticide next year.
The leaf was mined, not infected by a fungus. Mines are
excavated within a leaf. In the twisting, turning tunnels sawfly
larvae and pupal cases are still visible through the paper-thin
leaf surface. I think if you had seen them, L.G., you could have
guessed that they might overwinter in the leaf litter. Clean up and
destroy or hot compost all the leaves.
Leaf miner is nearly unheard-of in catalpa, but was reported in
scientific papers at least once before in your area, in 1982. So
you may never see it again. But do watch next June for mining, and
in that case check into appropriate insecticides.
Green thumbs up
to a healthy plant's ability to look after itself. Catalpa is
one wonderful example. When a leaf is chewed by catalpa sphinx
caterpillar, that leaf secretes a nectar that attracts ants. Then,
the ants defend the leaf against the caterpillar!
Green thumbs down
to those who'll write to me in the future about their lawn
problems and tree trouble, without thinking to mention that during
the 2004 Ryder Cup they parked twenty cars on that lawn. That
compacted the soil, killing roots and impeding new root growth.
Next year you'll see poor leaf growth and increased pest problems.
What you charged for parking should have included greens fees for
core aerating the lawn and vertical mulching the tree root
zones.
Originally published 9/25/04