Overwintering Mandevilla (Sun Parasol) Indoors in Cold Climates

Temperature Reality Check

Your cool bedroom is fine—Mandevilla doesn't need 45°F. It needs light, not cold. The leaf and bloom drop is from insufficient light, not temperature.

Light Requirements (Non-Negotiable)

• South/west window, blinds open dawn to dusk
• PLUS fluorescent fixture 12 inches above plant
• 14 hours daily (7 AM–9 PM on timer)
• Without this, the plant will continue defoliating

Watering Protocol

• Cut summer watering by at least half
• Use a moisture meter ($10-15)—water only when meter reads "dry"
• Never let sit in drainage water

Propagation Option

Take 4-6 inch semi-hardwood cuttings in spring (April–June). Dip in rooting hormone, root in perlite/peat mix under humidity dome. Higher success than overwintering the whole plant in marginal light.

Local Note

The expert is in northern Indiana (near Fort Wayne)—same climate zone, confirming these guidelines work locally.