Expert: Kenneth Joergensen - 3/12/2005

Question
i bought some begonia bulbs, but there are no directions on how to plant. how deep, which end up, sun/shade,  can you help me?

i live in zone 5.
thank you

Answer
Begonia bulbs are tender bulbs and should not be planted outdoors until after last chance of frost.

They can be started indoors 4 weeks perior to last frost date. In your area, last frost date (to be safe) would be memorial day, and you can start them anytime between now and end of march for earliest bloom.

If you start them indoors, make sure you have a window where you can grow them, or put them a few inches below flourescent light.

When you plant them, use a well draining planting mix (a container planting mix, or seed starting mixes available at garden centers). Place about 3" in the bottom of a 6" pot and then place the tuber on the potting mix. Make sure the concave (rounded) side is down. The hollow side should be up. Cover with approximately 1" of soil and then water once really well and let drain. Put in a warm place (on top of the fridge, or on top of the water heater) to heat the soil slightly (not too much). Once the sprouts appear above soil, move to a window or fluorescent lights immediately.

If you grow these by a window, make sure it is not a southern facing window. Begonias do best with morning sun only (eastern facing) or in filtered shade (behind a sheer curtain, or outdoors under the canopy of tall trees). All day filtered shade, or morning sun is best. Avoid full day sun, and hot afternoon sun.

During the growing period, keep the begonia consistently moist, but do not allow it to dry out, or stay saturated/soaked. Water and let drain (empty saucer). Then only water when the top of the soil is drying slightly. During hot periods of the year, watering more frequently may be needed.

Add a light application of houseplant fertilizer to the soil. You can buy bottles of 14-14-14 OSMOCOTE and add to the pot every 3 months. Use a LIGHT application.