Blogs Nov 7, 2019

3 Ways to Optimize Ornamentals Using LED Grow Lights

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It’s no secret that it’s both crucial and challenging to optimize ornamental production. Every variety has different production methods. Additionally, each grower has different goals around transplanting, flowering and finishing.

Photoperiod, light intensity, and light quality are all powerful tools that can help you achieve your scheduling goals and control your plants’ morphology.

Here are three ways using light spectrum and intensity for ornamental production can help meet these goals.

1) Add supplemental lighting to increase quality and reduce time to transplant for annual plugs

Want to time your spring plug production to meet early season demand? Since greenhouse production happens during the lowest light time of the year, adding supplemental light is a gamechanger when it comes to meeting your spring and early summer deadlines.

Using supplemental lighting in northern latitudes can save money by reducing time to transplant. In turn, shorter crop cycles reduce the amount of time that the greenhouse needs to be heated. Shorter crop cycles also mean that you can fit in more crop cycles during the season while using the same amount of space.

Additionally, increasing light intensity during plug production promotes root and shoot growth while keeping plants more compact. In other words, supplemental lighting improves your crop’s overall quality, and shipping and transplant success.


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2) Use blue light to promote compactness in low-light and sole-source conditions

Want to keep your plants compact so that they can better withstand shipping and transplant? Blue light can reduce stem stretch and promote plant compactness. Blue light triggers this response by signaling cryptochrome, a critical plant photoreceptor.

Increasing the percentage of blue light to 20-30% of total supplemental light (made possible using our smartPARTM software) can reduce plant stretch compared to lighting with predominantly red or green with less than 20% blue. As a result, LEDs with a targeted spectrum tend to produce more compact plants than high-pressure sodium (HPS) lamps. HPS fixtures provide relatively little blue.

While this plant response is reliable in sole-source plug production (which continues to become more prevalent), affecting plant compactness with spectrum in greenhouse production is a little less predictable.

LED Grow Light Scientist
What are the effects of spectrum in low-light environments?

The prevailing rule of thumb is that in order to manipulate plant morphology in the greenhouse using spectrum, the solar daily light integral (DLI) needs to be less than 7 mol·m-2·d-1 and/or supplemental lighting needs to account for more than half of the total DLI.

Since many major plug producing locations receive an ambient daily light integral (DLI) of 5 mol·m-2·d-1 or below during the plug growing season, increasing blue light during plug propagation is a good way to produce high-quality plugs.

3) Increase leaf coloration of foliage using spectrum

Color is king for ornamentals. Since plants partly use blue light photoreceptors to determine overall light intensity, increasing blue light prior to finishing can promote leaf coloration. Delivering up to 50% blue light at a photosynthetic photon flux density (PPFD) of 100 µmol·m-2·d-1 increases leaf coloration in both geranium and purple fountain grass, two crops where foliage color is critical for sales.

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What causes purple coloration in ornamentals?

Anthocyanin production is responsible for purple leaf coloration in both geranium and purple fountain grass. Plants produce anthocyanin in response to high light levels. Anthocyanin acts as a sunscreen to protect the leaves from photodamage.

As a result, purple coloration is naturally abundant in plants during summer or outdoor production. For this same reason, supplemental light is often required to signal plants’ anthocyanin production under low-light conditions.

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