What are Firefly (Bioluminescent) Petunias?

Glow-in-the-Dark, Flowering Annuals

Firefly petunias are glow-in-the-dark petunias; the first of their kind! Genes from a bioluminescent mushroom were transferred to a standard petunia, enabling them to subtly glow at night without the help of blacklights.

A sterile variety (no viable seeds) that can be grown in containers, hanging baskets, or gardens (as long as the weather isn’t too cold).

These bioluminescent petunias look like standard petunias during the day (white, pink, or white/pink combo), then glow a subtle lime green at night. 

Firefly Petunia

Quick Care Snapshot

Mature Size

  • 8″ T x 10″ W
  • Mounding form
  • Space plants at least 8″ apart so they receive adequate air circulation (helps prevent fungal issues)

Best Planting Time

  • Early Fall
  • Late Spring, after the danger of frost has passed.

Light Needs

  •  Full sun in fall.
  • Full sun in spring.
  • May need an AM sun/PM shade area as spring turns to summer.
  • Indoors: they need a very sunny spot, or the help of grow lights in order to gvie them enough light to “charge” for their glow.

Watering

  • Allow the top few inches to dry out in between watering.
  • Stick finger into soil to the second knuckle. If soil flakes off easily, water. If soil sticks, skip watering.
  • Containers may need more frequent waterings as they dry out faster, but always check first.
  • Always water at the base of the plants to avoid wet foliage which can lead to powdery mildew issues.
  • Petunias are not drought tolerant, but they also do not like overly wet soil.

Soil

  • Garden: well-draining, rich organic garden soil
  • Containers: high-quality potting mix (like FoxFarm Happy Frog), and make sure containers have plenty of drainage holes.

Fertilizer

  • Just like all petunias, and most flowering annuals, these are heavy feeders. And it is even more important that they get their regular feedings to keep the energy going.
  • Mix a complete (contains N-P-K), granular fertilizer into soil before planting.
    • These generally slow-feed plants for 4-6 weeks. Reapply according to package instructions (usually a month and a half later).
    • We like Rainbow Gardens Rainbow Bloom, or Nelson Plant Food ColorStar.
  • Use a diluted (1/2 strength) liquid fertilizer like fish emulsion or seaweed every other week. (Especially important when growing in containers as watering will leach out nutrients in containers faster than inground plantings.
  • Always water in fertilizer.

 

Pruning

  • Pinch dead flowers off just above the next set of healthy leaves.
  • If petunias get leggy and aren’t producing many leaves, try cutting them back about a 1/3 at a time to rejuvenate plant and encourage more leaves.
  • More leaves = More photosynthesis = More glow

Cold Protection

  • Ideal growing range is 65-75º F. (But can tolerate temps a little more to the left and right.)
  • Will need protection from frosts and freezes.
  • Also protect from hot summer temperatures.
  • Best grown in spring and fall.

Biological Recipe for How Firefly Petunias Glow

  • The Starting Material: The plant utilizes its natural caffeic acid.
  • The Transformation: A specific enzyme converts caffeic acid into a molecule called luciferin.
  • The Spark: Another enzyme helps the luciferin react with oxygen.
  • The Glow: This chemical reaction releases energy as a soft, green light.
  • The Reset: The spent molecule is recycled back into caffeic acid, and the cycle begins again.

Info: Garvillo

 

 

 

Petunia Firefly

Problems and Solutions

Green Foliage/No Glow

Cause: Most likely a lack of “glow” is due to lack of sufficient light exposure.

Fix: Make sure your Firefly petunias are getting 6+ hours of full sun. (In hot summers, they will need some protection from the late afternoon sun.)

Spots on Leaves

Cause: Possible that plants are crowded and not getting enough air circulation.

Fix:

  • Space plants at least 8″ apart. 
  • Check center of plants and thin out a few stems to open up plant.

 

Local Expert Tips

🌿 Rainbow Gardens Tip #1:
These are hot items and limited items. When we have them, they go fast and that’s it for the year.

🌿 Rainbow Gardens Tip #2:
They cannot tolerate frost. You can overwinter them indoors, but they must have a very bright area to grow in to continue the grow.

Visit Us

Find “Firefly” petunias at Rainbow Gardens (seasonally, and limited supplies).

 

Bandera Location

8516 Bandera Road

San Antonio, TX 78250

(210) 680-2394

Thousand Oaks Location

2585 Thousand Oaks

San Antonio, TX 78232

(210) 494-6131

 

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