I read and more or less followed your article on “overwintering caladium bulbs”. I simply cannot get them to sprout in the spring. This year I planted them (indoors) probably late Feb/early March. I placed them on my Lee Valley heating mat, I coddled them, but nothing. I had done so the year before also. Nothing. So this year I want to bring in the plants because they are so expensive to replace each year. I do not have a garage, just a (heated) basement. Do you have any suggestions?
Thank you for contacting the Toronto Master gardeners. I am sorry to hear that you are not having success in overwintering your Caladium bulbs. You are correct, they are an expensive bulb, but they really do make a bold statement in the garden. I must compliment the photo you included in this post. You have created a beautiful container using plants such as fuchsia and fern that enjoy the same requirements as your lovely Caladium. Its no wonder you would like to save it for next year!
My first question is what do your bulbs look like upon taking them out of storage in March? Are they shrivelled and dried up? If not, if they are still robust and firm to the touch, there should be no reason that they do not grow. The plants do not produce leaves in the winter and do require a dormant period. Bringing the plants inside may extend the leaves for awhile but the plant will still die back for the winter.
The key is having the correct climate for both the storage and then the potting of these bulbs. During the storage period you want to have them stored without moisture in a cool, dark place. I store my bulbs in the heated garage of my condo building, in peat moss (vermiculate is also good) in a brown paper yard waste bag. In March when I bring them up I discard any bulbs that are dried out and plant the firm ones in moist, but not sopping wet soil, making sure that the eye of the tuber is on the top. Overly damp soil in cool conditions will spell disaster for these bulbs. Once they start to grow they will need warmth and humidity. One tip (I received from bulb guru Dugald Cameron) was to place a little transparent plastic bag over each pot, hence warmth from the heating mat plus the bag imitates the tropical climate this plant is used to growing in, if you do try this method, watch carefully for mildew and remove bag if things start looking fuzzy! Honestly, I can claim only approximately 50% success rate with overwintering my Caladiums, so do not be too hard on yourself you do not always have a good outcome. Good luck and let us know how you did in the spring!
Here is a link to an article that might be helpful.