How to overwinter tuberous begonias in Western New York

Photo courtesy Rosemary K. Lyons

by Connie Oswald Stofko

Here’s a question from a reader:

I have beautiful tuberous begonias that I want to overwinter. Do I have to take them out of the soil or can I bring the window box in?

Rosemary K. Lyons,

Buffalo

tuberous begonias
Photo courtesy Rosemary K. Lyons

I thought this was a question many readers might be interested in, so I took it to David Clark, a nationally known gardening educator who teaches the Horticulture I and Horticulture II classes at the Buffalo and Erie County Botanical Gardens.

First, you should know that there’s a difference between tuberous begonias and wax begonias. Tuberous begonias grow from a tuber, which is a rounded, potato-shaped thing. Wax begonias grow from a fibrous root. (If you want to keep wax begonias over the winter, you can take cuttings and root them.)

The instructions for overwintering tuberous begonias will also work for plants such as dahlias, alocasia (elephant ear), cannas and gladiolus, Clark said.

To get to Lyons’s question: Yes, if it’s easier for you, you could leave the tuberous begonias in the soil in the box and place the box in the garage, he said. Don’t water them through the winter.

Here’s the process that Clark described for overwintering tuberous begonias.

Leave the tubers in the ground until you get a frost. That signals to the plant that it’s time to sleep, he explained.

Once the foliage dies down, dig up the tubers. Dry them on a screen so you have air circulating around them. Cut off the brown leaves and shake off the soil.

Next coat the tubers with a fungicide to help prevent rotting. You can use powdered garden sulfur, but Clark said he’s a big fan of cinnamon powder– the stuff you use for cooking.

Put the powder and tubers in a paper grocery bag, close the top, then shake the bag to coat the tubers.

Store the tubers in a container such as a paper bag, cardboard box or bushel basket.

Fill the container with a substrate, such as peat moss or wood shavings, that will keep the tubers from drying out completely. Don’t let the tubers touch each other. That will help prevent them from rotting.

“Make sure you label them because you won’t know what that thing is in spring, I guarantee that,” Clark said.

Set your container of tubers in a cool location. You don’t want the temperature to get above 50 degrees Fahrenheit, and you don’t want the tubers to freeze, either. An old fashioned root cellar in the basement is great. If you have an unheated garage, you could set your container near a wall that is close to the house.

Throughout the winter, check the tubers.

“Paw through them,” Clark said. “If you smell something, get rid of the rotting piece.”

In March you may see new growth. You can repot the tubers and put them in a warmer spot that has good light. Water them, but don’t soak them. This will wake them up for spring.

How to get information for yourself

Readers often contact me with questions that I can’t answer. I’m not a gardening expert– I’m a writer by profession. I interview knowledgeable people in order to provide you with great articles on Buffalo-NiagaraGardening.com.

So when someone asks a question I can’t answer, sometimes I post the question and rely on my readers to share their expertise by leaving a comment.

Sending a question to me to post can be helpful if you’re looking for a wide range of opinions and don’t mind waiting for the answer. If you want to try this route, email the question to me at connie@buffaloniagaragardening.com and I’ll pose it to my readers in an upcoming issue.

However, don’t send me questions:

  • To find out what is wrong with your plant
  • To identify a particular plant or insect
  • If you need an answer quickly

To find out specific information like that, it’s best to do what I did here: ask an expert. You can ask the Master Gardeners with Cornell Cooperative Extension or turn to your local garden center. They can give you the information you need.

Save

Save

Save

Save

Save

Save

Save

Save

Save

3 Comments on “How to overwinter tuberous begonias in Western New York

  1. I have escargot begonias.Can they be kept indoors thru the winter?If I want to overwinter them can they survive in a detached garage r do better in basement? Also what about Mandeville?

  2. Hello Pat!
    Escargot begonias are one of the most gorgeous begonias to grow! However, I have lost my share from fall to the next spring due to the following issues:
    1) They don’t like it too cool, or too warm. 60*F at night, and a 10-15*F change higher during the day.
    2) They do like medium humidity, good light, and fresh air movement. Keeping them on a large, gravel-filled tray with water almost up to the base of the pot will help with this.
    3) They can be prone to fungal issues on the foliage – I use ‘Safer’s Garden Fungicide’, a sulfur-based product on most of my house plants. Remove dead and dying leaves as they appear, to increase air circulation.
    4) Yes – they can be kept indoors thru the winter.
    5) Escargot begonias are a member of the Rex begonia tribe, those that like to be kept on the dry side.
    6) Eastern facing windows are best for this plant, as well as for many other houseplants.
    7) Water Rex begonias when to top 1/2″ of the soil feels dry.
    8) Avoid fertilizers on this plants as well as other houseplants from fall until spring – They don’t need it!
    9) For creepy-crawly insect pests, you can spray once a week with insecticidal soap or Neem oil for control.

    Mandevilla and other tropical plants can be tough to overwinter. I have found the best way is to leave them outdoors until the temperatures hover around the 50*F mark- this signals these plants to enter dormancy. I would prune it back by maybe 30%…
    The next step is to find a place in your home, basement, or attached garage where the temperatures again hover around 40-45*F.
    Reduce watering – the foliage will drop! During fall, winter – keep the plant dry, but DO add about a 1/4 cup of water, should you notice the soil pulling away from the sides of the pot….maybe 1X every week – OBSERVATION is your friend with this.
    Hopefully in the early spring, you will see new green growth appearing on the stems.
    At this point, you can increase the watering, light levels, and start a fertilizer program…
    Pat, I hope I have answered your question with not too much technicality!
    Regards,
    David Clark, CNLP

Leave a Reply

Your email address will not be published. Required fields are marked *

Name *