This article is about when and how to bring your begonias back indoors for the winter. It will be in two parts. Part one will be tips for Northern growers who have no choice about whether to winter their begonias indoors. Part two will be tips for Southern growers who may choose to do as the Northerners do or prepare their plants for a winter outdoors. There is no one method to follow when growing begonias or for how you winter them or bring them indoors. This article is to give you information and tips so you can formulate a plan that works for you and your growing conditions.
Part One: Northern Growers
Northern growers have the added hardship of having a limited growing period when their plants can grow outdoors. You can choose to do 2 things; you can leave your plants indoors all year or you can grow them outdoors during the warm months and bring them in for the cold ones.
Some of you may choose to only bring cuttings indoors after the summer. This has a plus side and a down side. One is you can save space by restarting new plants each fall from cuttings but if the cuttings fail then you have lost the variety. You can avoid some of the risk if you plan ahead. Most of you know when the first frost will usually come for your area. You should start your cuttings started well in advance of that first frost even before you have to start using the furnace. You’ll have more of a chance of success. You’ll give the newly rooted plants plenty of adjustment time. You’ll also have a chance to try again before losing the original plant outdoors by taking more cuttings if you have a problem.
Plants started early before the furnace starts running full time will have time to adjust to the lower humidity associated with forced heat. Cuttings taken from the cold, damp fall and rushed directly into the warm, dry indoors will be shocked for sure. Fall is a time when generosity can help you out too. If you start sharing cuttings with friends you can think of it as banking your begonias. If something were to happen to yours you’ll have a source for retrieval. You might even convert a few friends to begonias and gardening. You don’t have anything to lose. If you bring your plants indoors, you’ll probably still have to do some trimming and if you leave the plants outside they’re going to freeze anyway.
If you decide that you really want to bring the entire plant in instead, you still need to plan ahead. You can’t just wait till you think it’s going to freeze and then rush them indoors. They need to adjust just the cuttings would and gradually is best.
If you plan on bringing the entire plant back in every year, you should just plan on leaving the begonias in pots to begin with. Pots can be set in beds with plants around them to disguise the pots and make them appear to be planted in the beds. Or you can arrange the pots on shelves or a decorative display. The reason for keeping them in the pots is that it will be less stress on the begonia. If you plant in the ground, they have to go through being yanked out of the ground, having their tops trimmed and then going into a totally new environment. The potted plants may need some trimming back and maybe a few cuttings taken for insurance but they can basically be inspected for pests and then just brought back in. Whether the plants are in pots or in the ground, you still need to bring them in early just like with the instructions for the cuttings.
Plants in the ground will be more work, but the advantage is that in the ground your plant may have grown many times faster than it would have in a pot. The disadvantage is that you’re going to have to trim the tops back to match the size of the rootball. You have to remember that the begonia might have had several feet of roots supporting that big plant. You can’t expect to just dig it up with only a fraction of the roots, stick it in a pot and not have it go into shock. The lesser roots can’t usually keep up with the water required for all that top growth. It isn’t so bad though, you can root those extra cuttings and have either spare plants or backup plants.
Some plants may still require some extra help to adjust and recover. If you grow under lights you can accomplish this by tenting your light stand to keep the humidity in. You may want to do this even if your plants stay in all year. It does cut down on watering, and the plants grow more lush. Make sure to use non flammable plastic film and make sure it isn’t directly touching the light fixture. Clear plastic will allow you to see the plants even when covered. I also use trays filled with large perlite or gravel to set the pots on. This will give the water somewhere to go when watering. It will also raise the humidity if kept moist continuously. If you only have a few plants or don’t have a light stand, misting them frequently or placing them in an old aquarium to keep the humidity in will help. You can gradually remove the cover of the aquarium to adjust them to growing outside it.
When I grew in Iowa, I had an old redwood picnic table with two benches. In the summer the picnic table was a picnic table but during the winter it became a light stand. I would place it in front of an appropriate window with one of the benches on top. This gave me an area for growing plants in natural light. I hung a florescent fixture under the table and enclosed the table legs with plastic film. This gave me my florescent light growing area. I kept everything from geraniums to begonias through the winter under that redwood table.
I even grew a B. ‘Sophie Cecile’ under there, but at the time, being ignorant of begonias (I might still be ignorant) I thought it was some tropical species since it wasn’t named. I was very impressed with it and at the time had to save for awhile to buy it from a local greenhouse. I looked at it for a month and drooled over it before I had the $20 or whatever it cost. I had never seen anything so exotic looking before. Even then I tried crossing it with semps, the only other begonias I’d seen. I wasn’t successful but I remembered my experiences a few years later when I ran into a cane begonia again here in California. It was a B. ‘Pink Jade’ at a swap meet. I couldn’t pass it up since it was $5 and bigger than that B. ‘Sophie Cecile’ I’d had years before. I thought again I had really gotten a deal. I guess I did since it led me to the Begonia Society.
Part Two: Southern Growers
Many Southern growers will be following some of the methods above, especially if they don’t live in frost free areas. Likewise, many Northern Growers with be able to use some of the Southern tips to help them preserve struggling plants.
Besides having a much longer growing season overall, southern growers in some areas are even able to keep their begonias outdoors all year round. Even in those areas, there are some precautions and procedures that can be taken to assure the plants will survive the winter. In most southern areas, although it doesn’t freeze often or ever, they still have to contend with cold, wet weather. As most of you know, cold and wet are two conditions begonias hate with a passion.
So, what can you do about it? One procedure that I practice in my yard, I’ll call “crop rotation”. As the seasons change and the available light changes different begonias are moved to take advantage of the best light. In the winter, more delicate varieties are moved either into areas that have good winter light or that are more sheltered. Since the only way you can solve the “cold” problem is by constructing a greenhouse most of you will have to settle with solving the “wet” problem. Begonias can stand cold temperature much better than they can stand wet feet. Sensitive begonias can be moved under awnings or porch roofs, etc. to keep them from excessive rain. Some growers even go so far as to cover their shade houses with plastic sheeting. That will keep all the begonias dry. You will have to consider what your neighbors will say when it happens that you are standing outside watering your begonias in the pouring rain. If you choose to totally enclose the shade house with plastic, including the sides, you’ll have to take into account that there will be warm winter days. Your winter enclosure probably won’t have heat or cooling. I would suggest leaving at least one side open or that you can close at night or on cold days.
Many growers don’t have the option of covering or rotating because of limited space or limited time. Those growers have no choice but to just leave the begonias where they are. There are still things you can do. The most important thing is correct pot size. Do you have any plants that seem to stay wet all the time? Those plants are either over potted or root damaged or both. If they’re staying too wet now just imagine how wet they’ll stay this winter in the rain. Now is the time to correct the problem before it gets worse. Gently lift the plant out of its pot. You will see that some or most of the soil stays in the pot or falls off the plant when you lift it out. This shows you the plant is in too large a pot or that the roots have died to the point that they don’t hold the soil together anymore. In the spring, when you are moving plants up to larger sizes, it’s expected that many will be growing into those larger pots. During the winter, however, these plants will only decline further. The solution is to remove all the loose soil from the plant. Once the soil is removed, find a pot that is only slightly larger than the remaining rootball. Replant the begonia into the new pot. Next spring you will usually find the plant fully recovered and ready to move back up to a larger pot again.
If you live in an area that has an occasional frost some years, you should have precautions ready. Many growers save old sheets to cover the plants with if a frost is expected. Some also save large cardboard boxes to totally enclose plants with. Plastic sheeting can be used but if you also have rain, you can break plants. Plus, when the sun comes out, many plants can be burned by the heat through the plastic. A newer innovation is a type of plastic that has microscopic holes in it so it allows air, heat and water to pass through it but still protects from frost. I’ve heard from growers that have used it, that said they were able to keep the covering on for a couple of weeks without the daily removal and the plants were fine. This would be a big benefit over the other coverings which you will have to remove during the day and replace every night during cold spells. I can’t tell you the exact name of the plastic but it is available from most mail order seed companies, such as Parks Seed.
Though I haven’t tried this myself, I have heard from growers who live in areas with some frost, that trim back their begonias and mulch heavily with straw or a similar mulch. If you have found that you live in an area where the frost is just enough to completely freeze most begonias, you might try the mulching. You wouldn’t have anything to lose. When you trim back the plants, the cuttings can be taken indoors for the winter. The roots can remain in the ground under the mulch.
With all the different variables across the country, I can’t specifically tell anyone exactly what will work in their area. The suggestions above are to help you experiment in your yard to see what will be successful for you.