Can I Use String Lights To Keep My Plants In Veg?

The short answer is yes! When you extend the period of light past 12/12 (12 hours light, 12 hours dark) you can keep your plants from flowering using string lights, or other lighting options. However, this supplemental light form will not give the plants enough energy to grow, it will merely keep the plants from flowering. The number of days the plants should be under this lighting should be minimized. If kept in these conditions for too long, the plants will begin to stretch.

Photoperiod Lighting vs. Supplemental Lighting

• Photoperiod lighting is used to control flowering.
• The goal of supplemental lighting is to keep plants productive when natural light is scarce
• Supplemental lighting is used to increase light exposure to maintain photosynthetic productivity on days where there is little sunlight.
• The goal of photoperiod lighting is to control when crops flower. Photosynthetic lighting is lighting that helps plants grow. This type of productive light is measures in daily light integrals (DLIs).

For supplemental lighting, high-intensity light that measures 400-600 ft-c/50 to 75 µmol∙m−2∙s−1 from supplemental lighting is needed to increase DLI. For photoperiod lighting to keep short-day plants from flowering, any type of light can be used to interrupt dark periods or extend light periods (but it won't help plants grow).

Night Interruption Lighting vs. Daylight Extension Lighting

Night interruption lighting and daylight extension lighting do not need to be photosynthetically active like supplemental lighting. That is why even string lights can be used! If you want your plants to also get some energy, metal halide (MH), high-pressure sodium (HPS), and LED lights can be used.

Many people utilize cyclic lighting routines for night interruption lighting instead of using daylight extension lighting. This method interrupts plants with light after a period of darkness and tricks them into thinking the night length is shorter. Cyclic lighting techniques take a bit more planning but can help save money.