January 2022 - 33

PRODUCTION
greenhouse cover in mind. All
greenhouse structures and cover
materials block some light. Glass
greenhouses can reduce light by
30% before reaching crop level,
greenhouses of other materials
such as polycarbonate can reduce
light 55% relative to the outdoors.
This should be taken into account
when selecting the shade level of
your greenhouse curtains, as well as
in planning out your supplemental
lighting with LEDs.
Winter conditions matter a great
deal as well, as DLI decreases greatly
in the winter months in mid and high
latitudes. In the northern U.S. it is not
uncommon for outdoor DLI to drop
to 6 to 10 moles/day and interior
DLI to 2 to 4 moles/day. Growers
in these regions who need to grow
an ornamental or vegetable crop
throughout the winter months may
consider a transparent energy-saving
curtain as well. These curtains retain
heat underneath them to conserve the
energy used in greenhouse heating,
and their transparent structure allows
them to be deployed during the winter
days without sacrificing light. Indeed,
these curtains pair well with LEDs for
winter production.
BETTER TOGETHER
LEDs optimize screen systems and
vice versa, allowing growers to assess
and adjust the whole climate, rather
than impacting different parts of
both the plant and the greenhouse in
different ways. When you can't gap
screens, for example, you risk heat
and humidity buildup. Though today's
high-quality breathable fabrics allow
exceptional humidity control (for
example, Svensson's knitted screens
wick water across their yarns, helping
prevent humidity level extremes
and condensation formation on the
screens) climate challenges still exist.
That effect is much more manageable
with the cooler LED system pulling
less heat into the environment, for
less strain on the system. LEDs allow
you to reduce energy usage and heat
emissions while increasing light levels.
Effectively tailoring your curtains
to the right LED lighting gives you
the power to separate heat and light
to stabilize the greenhouse climate
and deliver maximum uniformity
year-round. You'll see the results in
shorter rooting time, increased
plant quality, higher turns and
increased productivity.
All signs point to the value of
integrating your supplemental
lighting and screening strategies
and products. Using the right
screening products and LED
lighting recipes together gives you
new levels of control to effectively
manage greenhouse climate,
optimize crop cultivation, and
ensure compliance with local light
pollution ordinances - all without
compromising your production
goals or your bottom line.
This article was written by Joli A.
Hohenstein, Pen & Petal, on behalf of
ACT. ACT is an educational platform
and collaboration of Grodan, Priva,
Ludvig Svensson and Signify, for
the purpose of advancing high tech
cultivation practices. Go to actsummit.
com to learn more.
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January 2022

Table of Contents for the Digital Edition of January 2022
