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Is T5 or T8 better for succulents?

When it comes to growing succulents indoors, providing the right kind of lighting is crucial for the plants’ health and survival. Two of the most common types of fluorescent lighting used for indoor gardening are T5 and T8 bulbs. But is one better than the other for succulents? In this article, we’ll compare T5 vs T8 lighting and help you determine which is the better option for your succulent collection.

What are T5 and T8 fluorescent lights?

T5 and T8 refer to the diameter size of the light bulb in eighths of an inch. A T5 bulb is 5/8 inches in diameter, while a T8 bulb is 8/8 or 1 inch in diameter. Both types of bulbs are linear fluorescent lamps that produce light by running an electric current through a tube containing mercury vapor and phosphor coating. The excited mercury vapor produces shortwave ultraviolet light that causes the phosphor coating to fluoresce, emitting visible light.

Light Type Diameter
T5 5/8 inch
T8 1 inch

Some key differences between T5 and T8 fluorescent bulbs include:

  • T5 bulbs are smaller in size and can produce very high light output in a concentrated area.
  • T8 bulbs have a larger surface area and disperse light more evenly.
  • T5 lights tend to be more energy efficient than equivalent T8 bulbs.
  • T5 ballasts can be dimmed, while most T8 ballasts operate only at full brightness.
  • T5 bulbs come in a wider variety of spectrums optimized for plant growth.
  • T8 lights are generally cheaper to purchase upfront.

Light spectrum considerations

When choosing grow lights for succulents, it’s important to consider the light spectrum they emit. Different types of light can affect plant growth, water intake, root development, and more. Some key factors to consider are:

  • Intensity – Succulents prefer very intense light. Look for bulbs rated at 5,000 lumens or higher.
  • Color temperature – Cooler light temperatures around 5,000-7,000K mimic natural daylight succulents need.
  • Red and blue light – These wavelengths drive photosynthesis. Make sure bulbs have enhanced red and blue spectrums.
  • Full spectrum – Bulbs offering a full spectrum with wavelengths from 400-700nm provide balanced light coverage.

Let’s see how T5 and T8 stack up in these areas:

T5 fluorescent light spectrum

  • High intensity – T5HO (high output) bulbs provide extremely high light levels up to 5,000 lumens in just a 2-foot bulb.
  • Color temperatures – T5 lamps are available in both warm (3,000K) and cool (5,000-10,000K) color temperatures.
  • Enhanced spectrum – Specialty T5 grow bulbs offer full spectrums enhanced with extra red and blue light.

T8 fluorescent light spectrum

  • Lower intensity – Standard 4-foot T8 bulbs provide around 2,200 to 3,100 lumens.
  • Color temperatures – Most T8 lamps fall in the cool 4,100K to 6,500K range suitable for succulents.
  • Standard spectrum – Fewer optimized grow light options. Full red/blue enhanced spectra rarely available.

For succulents, T5 lights offer far greater intensity and more customizable spectrum options tailored to plant growth. The high outputs and focused light of T5 fixtures give succulents the intensity they need to really thrive.

Growing succulents under T5 lighting

Here are some tips for setting up an effective succulent growing setup using T5 fluorescent lights:

  • Use T5HO high-output bulbs for maximum intensity. Combining both 6,500K daylight tubes with red/blue grow tubes provides a great balance.
  • Mount fixtures 6-12 inches above plants – succulents can tolerate very close proximity to T5 lights.
  • Run lights 12-16 hours per day. Use timers to ensure consistent daily photoperiods.
  • Use reflective surfaces around the grow area to maximize light exposure.
  • Arrange plants so light reaches all sides. Rotating pots regularly helps prevent stretching.

With the right T5 setup, most succulents will thrive and remain quite compact. The high-intensity light keeps them from stretching or etiolating. Using adjustable fixtures allows you to raise lights as plants grow.

Growing succulents under T8 lighting

T8 fluorescent systems can also grow succulents – you just need to adapt to the lower intensity and light dispersal. Here are some tips for a good succulent environment under T8 lights:

  • Use 6,500K “daylight” tubes for best color spectrum.
  • Position bulbs within 2-4 inches of plants for maximum exposure.
  • Run lights in split intervals, such as 5 hours on, 1 hour off to improve intensity.
  • Use reflectors above bulbs to intensify and direct light downward.
  • Rotate plants frequently to ensure even growth on all sides.

With T8 lighting, succulents may show some stretching toward light sources. But using reflectors, light cycles, and proper positioning can help compensate and allow T8 systems to effectively sustain succulent growth.

Comparisons of T5 vs T8 lighting

To summarize the key differences:

Factor T5 Fluorescent T8 Fluorescent
Intensity Very high Moderate
Light Dispersal Directional Wider coverage
Power Efficiency Very efficient Less efficient
Customization Many spectrum options Fewer plant growth optimized bulbs
Heat Output Low Moderate
Cost Higher upfront cost Very affordable

For growing succulents, T5 lighting has clear advantages when it comes to providing intense light, spectrum customization, and power efficiency. The concentrated light delivery and wide variety of optimized plant growth bulbs makes T5 a better specialized system.

However, T8 lamps work well for casual growing situations or combining succulents and houseplants. The lower intensity encourages succulents to stretch more, but is less likely to scorch other vulnerable plants. T8 fixtures are also inexpensive and readily available.

Ideal lighting setups

Here are two lighting configurations ideal for growing succulents indoors:

T5 Grow Light System

  • 2′ or 4′ T5HO fixture with 6400-6500K daylight tubes and red/blue grow tubes
  • Reflectors above bulbs to direct light downward
  • 12-18 hours daily photoperiod with timers
  • Light mounted 6-12″ above plants
  • Adjustable hangers to raise light as plants grow

T8 Grow Light System

  • Standard 4′ shop fixture with (3-4) 6500K fluorescent tubes
  • Aluminum mesh reflector above fixture
  • 10-14 hour split photoperiod, e.g. 5 hrs on, 1 hr off
  • Lights positioned 2-4″ above plants
  • Pothos or other trailing plants at edges to optimize light spread

Converting existing fixtures

If you already have fluorescent fixtures, you can upgrade them to work better for succulents by:

  • Replacing bulbs with high-output 6,500K daylight or full spectrum tubes
  • Adding reflectors above bulbs to direct light downwards
  • Mounting lights closer to plants, 2-6 inches above
  • Using timers and split intervals to increase intensity
  • Painting walls and surfaces around grow area white or lining with reflective material

With simple upgrades, most existing fluorescent fixtures can be adapted to provide succulents with adequate light. Combining enhancements like reflectors, closer spacing, and timers can make up for lower output bulbs.

Additional considerations

Here are a few other factors to keep in mind when providing lighting for succulents:

  • Supplemental sunlight – Even with grow lights, succulents benefit from natural daylight if possible.
  • Air circulation – Prevent mold/bacteria buildup with fans in enclosed grow spaces.
  • Heat – Monitor temperatures and ventilate to prevent excess warmth from grow lights.
  • Fertilization – Use half-strength balanced fertilizer to fuel growth under artificial light.
  • Pests – Check for common pests like mealybugs which can spread rapidly indoors.

Attending to factors like sunlight, air flow, and nutrients ensures healthy plants that can make the most of your grow light setup.


For dedicated succulent growing setups, T5 fluorescent systems provide higher intensity light and spectrum customization that helps succulents really thrive. The concentrated light design suits the preferences of most succulents.

T8 lighting can also sustain succulent growth, especially if enhancements like reflectors and split photoperiods are used to maximize light exposure. For multi-purpose spaces or mixing succulents and houseplants, T8 systems are a cost-effective option.

Optimizing factors like photoperiod, spacing, and supplemental sunlight can help both T5 and T8 lighting successfully support an indoor succulent collection. Concentrating on providing intense light will lead to vibrant, compact growth.