Using Light to Grow Plants

Key Points

In this piece of content you can learn more about how light can be used to help your plants grow:

Give your plants a boost with the right lighting
Call the team at LampShopOnline to find out more on 0113 8876270 or email
tomato grow lights

The unpredictable nature of the British weather can sometimes prove problematic for gardeners, especially if they want to try their hand at growing fruit and veg. Sunshine is key for producing a successful crop, so therefore, a dreary summer can result in an even more dreary harvest.

With this in mind, it is worth considering boosting growing potential by planting crops indoors and using specially designed lamps to allow you to grow plants all year round. The right kind of artificial light can extend the growing season of your plants, giving crops a helping hand and ultimately help you achieve the best possible results.

Top tips for growing plants indoors

Steve Alexander, owner of Chillies on the Web uses growing lamps to ensure that he can grow the highest quality produce for his business, come rain or shine. To grow the chillies sold on his website, Steve uses 30 watt T8 Gro-Lux lamps from Lamp Shop Online, which are specially designed to help plants grow in an indoor environment.

Here are Steve’s top tips on how to start growing your own produce from the comfort of your own home:

  • Plants of all types will require good conditions, however, the consistency of these conditions is paramount.
  • By providing a set amount of light for a set amount of time per day, plants can create a consistent amount of energy. This in turn creates great plants, growing very quickly.
  • Growing larger produce requires a lot of patience and commitment.
  • It is essential that you have the right amount of space to successfully grow your crops, and you may have to be prepared to clear space in your garage or shed to make room for your growing projects.

What lights are necessary for different plants?

The lighting used for growing crops varies depending on the type of plant you want to grow, so unfortunately, when kitting out a growing room or greenhouse, it isn’t always a case of one type suits all.

Every plant has different lighting requirements, and could potentially respond to different light spectrums, which is the color of light within the full spectrum. For example:

  • The BLUE SPECTRUM of light enhances leaf and vegetative growth.
  • The RED SPECTRUM encourages flowering.

It is possible, however, to combine different coloured lighting spectrums to suit particular planting needs.

It’s essential that you choose the right light for the type of plant you want to grow, to ensure effective photosynthesis. You don’t necessarily need to invest in huge, expensive lighting for basic growing, and you will generally only need small lights for smaller produce. However, successfully growing fruit and vegetables takes a lot more effort, and will most likely require specific lighting.

tomato grow lights

The benefits of different types of grow lighting

Fluorescent grow lights

  • They are excellent for stimulating the growth of seedlings.
  • They are capable of shining the full light spectrum.
  • They emit lower heat than most other types of light, meaning that they can be put directly over seedlings without damaging them.
  • They are perfect for smaller areas, however, they aren’t suitable for supplying light to larger areas such as a greenhouse.
  • T5 fluorescent lights are more efficient and lightweight than other fluorescent lights, making them particularly useful for plants.
  • T5 lights also produce a greater light intensity, whilst using less energy.

Metal halide grow lights

  • Metal halide grow lights emit the violet and blue light spectrum which helps plants to develop strong roots.
  • They are often used as a primary light source when sunlight is unavailable.
  • They last for long periods of time, averaging 10,000 hours.
  • This type of light also promotes leaf and vegetative growth, and is therefore useful for green leafy vegetables.
  • Metal halide lights are best used for starting off seedlings, and supporting early plant development.

High pressure sodium grow lights

  • High pressure sodium grow lights cast the orange and red light spectrum, which encourages flowering and fruiting in plants.
  • This type of spectrum is prevalent outdoors during the summer and autumn seasons.
  • These lights are most often used to encourage mature plants that are beginning to produce fruits.
  • They are best used in larger spaces such as greenhouse to supplement other light sources.
  • They can last for up to 18,000 hours.

LED lights

  • LED lights are not recommended as a grow light for specialist plants, as they can cast an unnatural light appearance on plants.
  • They are only suitable for simple, year round kitchen growing, such as salad and herbs.

Incandescent lights

  • Incandescent lights cast a reddish yellow spectrum, but lack the amount of blue light required for successful growing.
  • They emit too much heat to be suitable for growing plants.
  • The only way that they can be used to benefit plants is when they supplement other lights for growing house plants.

Where should the light source be positioned for maximum effect?

Bulbs will need to be positioned the correct distance away from your plant.

  • If the light is too far away the plant will not be able to absorb a sufficient amount of light.
  • If the lamp is too close then this could result in the bulb burning the plant. A good test is to place your hand where the light hits the leaves, if you can feel any warmth, that usually means that the light is too close to the plant.

The optimum distance between light and plant may vary slightly depending on the type, but a general rule is:

At least 10 inches (25.4 cm) away from the plant, but no further than 40 inches (101.6 cm).

How much light do plants need?

As artificial light is being used to emulate natural light, it is obvious that plants will need some time out of the light, just as they would if they were planted outside. In the dark plants resperate, which is essential for the growth process, and the balance of rest time to active growth time can also affect the setting of buds and fruit. Therefore, it is important that you periodically give your plants a break from grow lights.

In general, a common duration of light is 12 hours. However, if you wanted to be more specific with your timings, Botanists divide plants into three categories which reflect their preferred day length: short-day, long-day or day-neutral.

Short-day plants will thrive on less than 12 hours of light per day.

These include:

  • Chrysanthemums
  • Kalanchoe
  • Azaleas
  • Begonias

Long-day plants require at least 14 to 18 hours of light each day.

These include:

  • Most vegetables
  • The majority of garden flowers

Day-neutral plants thrive on just 8 to 12 hours of light all year-round.

These include:

  • Foliage plants
  • Geraniums
  • Coleus
  • African violets

How do I ensure that the plants are receiving the optimum amount of light?

The following tips will help keep your bulbs in good condition and, as a result, make sure that your plants are thriving.

  • Rotate and (if possible) rearrange your plants on a weekly basis. This will ensure that the each side of the plant will receive an even amount of light. You will also find that the centre of a fluorescent tube emits much more light than the ends, so plants in the centre are likely to receive more light than those on the edges.
  • Keep an eye on the bulbs and change them when they begin to age. This is easily spotted on fluorescent tubes as the ends of the tube darken. The output of the bulbs lessens with age, so much so that the output of an old tube could be less than half of that of a new tube.
  • The amount of light emitted from a bulb can be greatly reduced if the bulb is dirty or dusty. Clean all fluorescent bulbs each month to ensure that the maximum amount of light is being let out.

Plants in the spotlight

It may seem like choosing the right lighting for your plants is a bit of a minefield, but you will find that grow lights are readily available here at LampShopOnline, including the Gro-Lux range from Sylvania. Simply check on the recommended lighting for your particular plant’s requirements and you can easily locate the correct lighting combination from our wide range of bulbs.

By using the correct lighting, you will have the best chance possible of growing year round, healthy and happy plants, no matter what the Great British weather has to throw at us. If you need any help at all, call the team at LampShopOnline on 0113 8876270.

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Published 2014/05/14

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