The classic medium for woody cuttings is Cornell mix. It is composed of:
50% sphagnum peat moss and 50% horticultural pearlite or vermiculite.
Most evergreen rhododendron and azaleas may be propagated from stem
cuttings. Cuttings are usually taken in the early fall from new growth
that is just hardening off. Cuttings are taken in the morning when full
of moisture. The cuttings are usually terminal cuttings with one whirl
of leaves with the leaves cut in half (to reduce the leaf area) and any
flower buds removed. The cutting has the end cut off just before placing
in hormone powder (containing a fungicide). Then the cuttings are placed
in a flat of sterile media containing a mix of 50% peat moss, and 50%
horticultural perlite or vermiculite. The flat is placed in a
polyethylene bag with struts to keep bag away from the foliage and
placed in a light area with no direct sunlight. The flat is rotated once
or twice a week to compensate variations in light and temperature.
Usually bottom warmth of 75?F is used to encourage root growth. Rooting
usually takes about 6 weeks for evergreen azaleas and 3 to 4 months for
large-leaf rhododendron. Once the cuttings have rooted, pot or
transplant them to flats containing a sterile mix of 60% peat moss and
40% perlite. Fertilize once a month with an acid-based azalea plant food
like Peters. Removing terminal buds promotes sturdy well branched
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It's definitely not potting soil.
BTW, I learned the trick a few years ago of sprinkling a thin layer of
sphagnum moss to cover the mix. Stops "damping off", also known as
And I always water from the bottom.
Most have large portions of coarse matter. Knocks rooting hormone from
the stem while planting. Undoubtedly also produces air-filled pockets --
NOT desirable. Sifting helps, but it's a PITA for whole sacks of dirt.
Haven't had damping off since using flourescents for starting, and I tend
to overwater. Some germicidal UV must be leaking through.
Spritzer or teaspoon. Great thing about plain sand is, a trickle
of water when planting will collapse any air pockets underneath.
I use a 50-50 mix of peat moss and clean sand. NO NUTRIENTS.
The mix holds moisture quite well but also has almost perfect
drainage. Peat moss is somewhat acidic, which inhibits fungus and
rot. Thus, when mixing, it's best to over-measure the peat moss
instead of under-measuring it. For sand, I use "washed" plaster
sand. It's washed in processing; you don't wash it.
Nutrients promote the micro-organisms that create compost (and
which cannot be avoided unless you bake the mix to sterilize it).
David E. Ross
Climate: California Mediterranean
I use exactly the same mixture of sand and peat moss you do. I don't use
"washed" plaster sand but buy a bag or two of play sand along with large,
translucent storage boxes with translucent covers from Wal-Mart. I then
place a half inch layer of play sand in the bottom of the box and dampen it
before putting in the cuttings into the deep six packs. I put the cover on
a box and set it in a shaded area on our front porch. I open the cover for a
few minutes every other day to air and remove all dead leaves. Within a
month to six weeks most cutting have rooted. (It's easy to tell because
rootlets begin showing on the bottom of the six packs.) As soon as rootlets
begin showing on a six pack, the six pack is moved to another translucent
container with sand in the bottom with the top is left partially ajar until
they harden. This takes about 4-5 days at which time they are planted into
One shrub that gives me fits is the korean spice viburnum. Three other
viburnum varieties have rooted and been planted, but not that beast. It has
been sitting in the rooting box with green leaves and no roots since June 1.
Does anyone have any idea what I'm doing wrong? :(
You're problably doing nothing wrong. First of all, if you get 50%
of your cuttings to survive and root -- 25% of cuttings from woody
plants -- you are doing well.
Woody cuttings can be real slow to root. An azalea cutting took
about 3.5 months this year.
Some perennials, however, seem to root overnight. Six weeks ago, I
took cuttings of red clover (Persicaria capitata, a ground cover
with clover-like flowers). Last week, I noticed roots growing
through the bottoms of the little plastic pots I was using.
However, only three out of four cuttings survived. Once I plant
them in the ground, about a third of the rooted cuttings of this
ground cover die.
David E. Ross
Climate: California Mediterranean
Thanks for the encouraging words, David. I managed to start and grow four
out of dozen korean spice cuttings two years ago, but none rooted for me
last year, and none have rooted for me so far this year. My problem is that
a very good gardening friend asked me to start one for her, and so far I'm
striking out. It bugs me because I'm accustomed to 50% or better success
with shrub cuttings with the exception of ilex. Tried them, no success,
quit! :) I usually donate around a hundred shrubs in gallon pots to our
garden club's annual plant sale.
I'm lazy, so here's how I do it. I get a bag of "Ferti-Lome" potting
soil, which has a LOT of peat. I get the compressed-peat pots, and a
plastic tray. Put dirt in pots, put pots in tray. When you want to water,
pour water in the tray. It'll soak up through the peat pots. Some seeds
don't like having the peat holding lots of water, and don't do so well.
Most things, however, do just dandy.
took 3 cuttings of Oliander, several cuttings of various Lantanas;
trimmed them to few leaves, big ones clipped in half, and filled pint
jars with water, placed siran wrap over the openings, poked holes for
each plant in the tops and inserted the clippings. 8/07/04 Oleanders
sprouting. 8/13/04 potted 3 well rooted Oleanders in about half
contractors sand and MG potting soil and they are doing really well..
they never ever looked stressed the whole time. they were on the
dining table on the patio shaded but good light. two of the Lantana
are nearly ready to pot but the specie I wanted most is not sprouted
as yet; however it is still fresh looking so hoping. On 8/11 have 3
plastic tubs of same mix soil and stuck bunch of jade leaves and
cuttings, Xmas cactus, coleus,pencil cactus, bunny ear cactus and
sansavarious and can't remember what else and they are also doing well
and most of them already feel like they are taking root. hoping to
have ready for church pot plant sale, too. Did Spirea same way,in
I have found pure Perlite, medium particle size works for almost
everything. I have an automatic mister which I control to spray every 30 min
at this time of year, maybe only every couple hours in cool damp weather. I
do use a rooting hormone too. I root a lot of stuff and even reuse it
sometimes for easy stuff like Rosemary. Use clean material if you are just
using a little. Repotting after rooting for some things is sometimes tricky
because the roots you get this way are a tad abmormal and you have to use a
very well drained potting soil and even an occasional foilage wetting until
normal feeding roots develop. Feed with fish emusion for awhile. I once
rooted a bunch of lilac and then lost a lot in the transplanting process by
not paying enough attention at this stage.
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