LED Horticultural Grow Lights Make Propagation Easier and Faster

Rooting cuttings in separate propagation room cuts a week off of production schedule
by David Kuack and Jean-Marc Versolato
Minnesota in the winter
is not the ideal place to try to propagate woody ornamental cuttings. Cold
temperatures and low light conditions make rooting cuttings a real challenge. So
when Jean-Marc Versolato at Bailey Nurseries in St.
Paul, began reading about how European growers were
using LED lights to root cuttings it piqued his interest.
who is the company’s IPM manager for the greenhouses, worked with Philips Horticultural
Lighting and Hort Americas to design a separate propagation room not in the
greenhouses to trial the LED lights.
felt that the LED lights were going to be the next improvement in growing,”
Versolato said. “We started in February 2011 and ran a variety of crops under
the lights. We used three Cannon carts tied together side-by-side to form one
large shelf that can hold up to 15 trays. The trial was conducted in a corner
of our germination room.”
said the germination room was the perfect location for the trial. Located
inside a production building, the room provides a constant 70°F and is equipped
with fogging nozzles in the ceiling. The trial propagation area was partitioned
with black plastic to avoid light contamination from the room’s fluorescent
cuttings only received red and blue light from Philips GreenPower LED production modules. The 5-foot modules, which matched the size of the carts, were
located about 16 inches away from the cuttings.
were taken from a variety of plants in the greenhouses, including Spirea, Celastrus,
Physocarpus and Hydrangea. The cuttings were sprayed with indole-3-butyric acid (IBA) to help initiate rooting. The
cuttings were stuck in 38-cell plastic trays (standard 11- x 21-inch)
containing Preforma rooting plugs. The cart shelves held five flats of each
genus for a total of 15 flats.
fogging nozzles filled the entire room with fog. There cuttings received no direct
water misting or spraying.
using the fog we eliminated droplets from forming on the foliage, which greatly
reduced the chance for Botrytis and loss of cuttings,” Versolato said. “Gravity
caused the fog to descend on the cuttings and the fog kept the cuttings turgid.
LED lights generate heat, but nothing like other lights available for growing.
For this reason the Preforma plugs remained moist and we didn’t need to apply
any additional water.”
cuttings rooted in three to four weeks. Versolato said in the greenhouses the
cuttings root in four to five weeks and occasionally take longer for some
Crops on Cannon carts under fog and Philips LED Grow Lights
Trialing other
the initial propagation trial proved successful, Versolato was looking to try
additional crops. During the summer the company purchased tissue-cultured lilac
rooted three flats of micro-cuttings under the LED lights in three weeks,” Versolato
said. “They required very little grower care whatsoever. The environment in the
propagation chamber was controlled by the LED lights and the fogging nozzles. Also,
no fungicide spray applications were made.”
said winter cutting propagation in the greenhouse can be difficult to manage
because of low light levels, the temperature and the humidity. Based on the
successful results of the lilac trial, Versolato said the company plans to root
25 percent of its French lilacs (Syringa
) cuttings in the propagation room.
January and February we will begin to root the micro-cuttings lilacs in the
room,” he said. “We are probably going to root six to seven varieties, putting
a sample of each one of them under the LED lights to see how they perform.
We’re going to do six carts with three shelves each. Each shelf holds five
trays, for a total of 90 flats under the LED lights. This trial will be our
first multi-layer production attempt.”
pleased with the rooting results under LED lights that he has gotten so far,
Versolato said he thinks there are other factors that are instrumental in the
cuttings rooting faster.
cuttings are being rooted in the Preforma plugs instead of greenhouse growing
media,” he said. “The chamber also has very good temperature and humidity
control. All of these factors put together help to shave seven days off of the
rooting schedule.”
said the propagation room will be used for hard to root crops. The room can
hold 40-50 carts.
are not going to be wasting space in the trial area for crops that are easy to
root in the greenhouses,” he said. “We are looking at a list of a dozen
varieties/species that we would root in the room knowing that they are
difficult to root in the greenhouses. Some of the plants that will be trialed
include Rhus typhina ‘Bailtiger’ Tiger Eyes, Amelanchier and Betula.”
the lilac trial, 15 flats of cuttings were lit by five modules of LED lights.
wanted to be sure that we had enough light for all of the flats,” Versolato
said. “For this coming year the lights are not going to be directly above the
plants or mounted on the carts. We want to be able to move the carts in and out
of the propagation room.”
lights will be mounted on a bracket shelving system and located about 16 inches
above and to the side of the cuttings. Versolato said this will make switching and
handling carts a lot faster and easier.
The right recipe
said the red and blue LED lights come in different recipes depending on what a
grower wants the plants to do, whether it’s develop roots, hasten flower initiation
or speed up time to flower.
recipe that we are using is generic and works with just about any plant we are
trying to propagate,” he said. “It would be too difficult to have a different
recipe for every genus and species that we are growing.”
said Philips can provide growers with the information to tweak the light
wavelength recipe to increase or decrease the amount of red light or blue
Dutch growers, who may be producing acres of Anthurium or another mono crop, it
is easy for them to have a specific light recipe for that one crop,” he said. “But
in our situation where we have many different crops, it would take a lot to
come up with a different recipe for each one of them.”
Finished crop on Cannon carts (multilayer production)
under LED grow lights
Finishing plants
is also planning to do another trial finishing plants in the greenhouse under
LED lights.
has different types of LED lights,” he said. “In addition to the light modules
we used for propagation, Philips also has flowering light bulbs that can be
screwed into regular light fixtures. One helps to promote flowering.
is planning to do a small trial with the flowering LED lights to see if they
help with flower bud initiation on impatiens during early season crop
production. He said the first impatiens crop is grown during the short dark
days of the year and the plants are very slow to develop buds.
though the first crop is currently grown under high intensity discharge lights,
Versolato wants to see what impact the addition of LED lights will have on the plants.
want to try some LED bulbs mixed in with the HID to see if they help to improve
bud count,” he said. “The crop would be put out in the greenhouses around Feb.
23. The light level in the greenhouses in Minnesota during February is very low. We’re
planning to trial about three benches with the LED lights.”
For more: Bailey
Nurseries Inc., www.baileynurseries.com. Hort Americas,
www.hortamericas.com. Philips
Horticultural Lighting, www.philips.com/horti
David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com. Jean-Marc Versolato is IPM manager, Bailey Nurseries in St. Paul, Minn.
Visit our corporate website at https://hortamericas.com