Phalaenopsis Not Growing or Spiking: Light, Fertilizer, and Temperature

Orchid Won't Produce New Growth or Spike

Theo bought a Phalaenopsis for parents 3 years ago; it spiked a few times despite poor care. He brought it to his apartment to induce flowering, but it won't grow or spike. Temperature is mild, repotted with good drainage.

Expert Response

Theo, you didn't mention light. An east window with morning sun works well. Increasing light is essential for flowering. Dark green leaves indicate insufficient light; they should be light green. The plant may not be mature enough to flower. Focus on strong new growth: use balanced fertilizer (20-20-20) at 1/2 tsp per gallon with each watering. Fertilizer plus added light should encourage growth needed for flowering.

Follow-Up: History and Current Conditions

Theo adds: plant was mature with large yellow flowers lasting months when purchased 3 years ago. At parents' place, it was near north/east windows. He tried different spots in his apartment with little improvement. Once saw an off-shoot but center leaves rotted. Now a dormant main plant with small off-shoot. Recently moved to spot with morning sun until 10 AM. Using TerraCycle orchid food (worm poop) in spray bottle, which worked on other Phalaenopsis.

Second Response

Theo, I lack confidence in worm droppings as fertilizer. It's organic, urea-based; urea must break down to release nitrogen. It's low in phosphorus (bloom booster). Since plant is mature, switch to high-phosphorus fertilizer (e.g., 30-60-20) labeled "bloom booster." Add supplemental lighting on a timer, extending day length by a couple hours. Some Phalaenopsis need a night temperature drop (55-60°F) to initiate flowering.

Second Follow-Up: Winter Concerns and Dendrobium

Theo worries about cold NY windowsill in winter. Asks about watering less in winter. Also has a Dendrobium from Trader Joe's (bloomed 3 months, then lower leaves yellowed and fell, only two top leaves left). Asks how to revive it. Notes TerraCycle says "no urea" and is for orchids; he'll look for recommended bloom booster.

Third Response

Check nighttime temperature by the pot—okay down to 50°F. Grow drier in winter; cold + wet causes root damage. On cold cloudy days, move plant away from window. TerraCycle likely processes worm castings to speed urea breakdown. Dendrobiums are harder: two groups—warm and cool growers. Cool growers flower from canes; warm growers from spikes near cane top. Most have extended rest period, are deciduous. Many kill them by watering during rest—when leaves fall, suspend watering until new growth appears. If canes shrivel, mist lightly. Dendrobiums need much more light than Phalaenopsis to bloom; move outside in semi-shade when temps stay above freezing, acclimating slowly. When new growth starts, feed with every watering—they're heavy feeders.