How can I stop paperwhite bulbs from developing mold when forcing them inside?

Question

I recently planted a few paperwhite bulbs in river rock with water. They've started to root and sprout, but I noticed one of them is developing mold. What's the best way to fix this problem? Should I scrape the mold off of the bulb and hope it doesn't come back? I would need to move the bulb to do so, and I'm afraid I could damage the delicate roots in the process.

Other notes:

• I had been trying to keep the water level covering the bottom 1/4" to 1/2" of the bulbs, but now that they're putting down roots, I'm aiming for just up to the bottom of the bulbs.

• The bulbs are in a fairly sunny spot on our dining room table. The room has two walls of windows (South and West facing) that we usually keep the blinds open on.

• The temperature in the house has been between 70°-75°F for the most part. Possible a bit lower at night, since we really haven't started running the heat here yet.

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Answer 1

• I had been trying to keep the water level covering the bottom 1/4" to 1/2" of the bulbs, but now that they're putting down roots, I'm aiming for just up to the bottom of the bulbs.

Having the bulbs themselves constantly sitting in the water, even such a small amount is the most likely cause of the mold (IMHO).

If it was me, I would:

• Very! carefully remove the bulbs, then clean the mold off of them, again very! carefully.

  • Use an toothbrush or small nail brush and clean water.

• Allow the bulbs to dry naturally for a few days.

  • Use glasses (or some plastic containers) that are large enough for the bulbs to sit on top of and allows their roots to dangle down into them. Fill the glasses with enough water so the roots sit in the water but the bulbs themselves don't touch the water.

• While the bulbs are drying, empty the water from the glass vase and take out the stones.

• Then clean the glass vase and stones with a mild bleach solution (5% maximum). Rinse thoroughly with clean water afterwards. Dry with paper-towels, then allow to air dry.

• Once the bulbs have been allowed to dry for a few days (while their roots sit in water), put the stones back into the glass vase. Carefully put the bulbs back on top of the stones, ensuring their roots go as deep as possible into the stones, then fill the vase with clean water -- making sure finished water level does not touch any part of the bulbs, keep the water level about ¼ to ½inch (6.25 to 12.5mm) below the underside of the bulbs.

  • Check the bulbs are sitting firmly in place once you've got everything set-up, back in place...

• The bulbs are in a fairly sunny spot on our dining room table. The room has two walls of windows (South and West facing) that we usually keep the blinds open on.

• The temperature in the house has been between 70°-75°F for the most part. Possible a bit lower at night, since we really haven't started running the heat here yet.

Those conditions sound pretty good to me, though the temperature is getting a little bit on the warm side but should be ok! (60 to 70°F would be ideal).