Using spectrometer to measure the growth of houseplants

How does light affect plant growth?

Light is one of the most important factors for growing houseplants. All plants require light for photosynthesis, the process within a plant that converts light, oxygen and water into carbohydrates (energy).

Plants require this energy in order to grow, bloom and produce seed. Without adequate light, carbohydrates cannot be manufactured, the energy reserves are depleted which leads to the death of plants

Visible light

For sufficient rates of photosynthesis and chlorophyll concentration, plants require a visible spectrum of light ranging from between 380 to 700 nanometers. In the plant science and horticulture world, we sometimes refer to this spectral range as photosynthetically active radiation – or PAR for short.

The light that falls within this spectral range affects plant growth differently. Plants use violet and blue light waves, between 400 to 490nm, for vegetative growth. While red light, which falls within narrow spectrum between 580 to 700nm, is used by plants for reproductive growth.

Because wavelength range from 490 to 580nm is green light, which isn’t used frequently because this light isn’t absorbed by plants . That’s why our eyes see most plants as green. Plants absorb the violet-blue light and the orange-red light and reflect most of the green light that they receive.

Ultraviolet light

Plants also use small amounts of ultraviolet light (UV). There are three different types of ultraviolet light broken down by their respective wavelength:

• UV-A radiation: 315 to 400nm – in regulated administrations UV-A can help plants to produce robust plant growth.
• UV-B radiation: 280 to 315nm – in small amounts UV-B prevents fungal infections from attacking and spreading on an indoor plant. It is neccesary to limited to short periods when usuing UV-B, as it can alter plant DNA and inhibit a plant’s ability to photosynthesize.

• UV-C radiation: 100 to 280nm – UV-C is harmful to plants.

Infrared radiation

Although infrared radiation (IR) isn’t necessary for photosynthesis, it produces heat that is used by plants in two different ways:

• Infrared radiation increases plant growth:  Normally, by competing for natural sunlight, plants cover one another as their race to the sun causes them to grow taller and spread out further. It lead to the covered one not able to race to the sun, which we need filtered light that the covered plant receives contains high levels of infrared light. This help covered plants grow at a faster rate and reposition itself in a spot where it is once again receiving optimal amounts of sunlight – a phenomenon that results in a rapid spurt of growth.
• Infrared radiation promotes blooming: IR stimulates the growth of phytochromes, a photoreceptor that regulates plant development, leaf distribution, stem growth, and reproductive growth. Because the days in the summer are longer, more infrared light is delivered to outdoor plants. Therefore, under grow lights, houseplants are stimulated by IR and grow reproductively no matter what season it is, just as they would outside during the warm spring and summer months.

Best light spectrum for vegetative growth

Blue light for plants, between 400 and 490nm, is the perfect spectral range for vegetative growth.

If you’ve had your eye on a fluorescent grow light, you may have noticed that these types of lights often use a measurement of Kelvin rather than nanometers. Kelvin (K) is a measure of temperature or, in the context of plant growth, a measurement of color temperature.

To put this into perspective, 1,000K gives off a warm/red color and 10,000K gives off a cool/blue color. With that in mind, you’ll want to find yourself a setup that delivers around 5,000 to 7,500 Kelvin for vegetative growth.

Best light spectrum for flowering plants

Red light, between 610 to 700nm or 2,000 to 3,000K, is the best for flowering and fruit production. Within this spectral range, artificial light produced by grow lights emulates the lighting conditions that are common during the spring and summer months – when plants flower and fruit.

Best full-spectrum light for plants

There are grow lights out there that will deliver both red and blue light simultaneously, this is referred to as full-spectrum lighting. When a manufacturer refers to full spectrum grow lights what they mean is their product has an integrated feature that allows growers to switch in between vegetative and reproductive modes or deliver both at once.

Best light spectrum for aquarium plants

As with most terrestrially based plants, aquarium plants also enjoy full-spectrum grow lights that produce artificial lighting that falls within both the red and blue spectral range. Therefore, full-spectrum lighting that produces blue, green, yellow, and red light, ranging from 400 to 700nm, is best used for aquarium plants.

For the seperated purpose, it will have the different wavelength ranges to optimize the results. As the information are mentioned above, Ocean Insight Flame miniature spectrometer with the features such as interchangeable slits, indicator LEDs and simple device connectors deliver more freedom and less

frustration with setups. With the detector range from 190-1100nm, it can be customed to fit with the specific plants requirement.