Help! How to overwinter these?

[Gncq]

Hello, a lovely neighbor just dropped off a couple of bags of plants that I said I'd like.

I'm pretending to know about gardening, and asked her (while socially distancing) what do you recommend I do with them? She did seem in a hurry and rushed off a few ideas eg keep them in paper??

So help me out gardeners, I'd like these plants to grow well in spring we have:

Dahlias and Begonias. How do I best look after them over the winter?

Dahlias

Begonias

They need to be stored somewhere dry over winter, as they aren’t hardy. A shed or garage should do, some people store them in trays of peat(!), but they can be wrapped in paper as your neighbour said. They need to be dried out so that the tubers don’t rot before wrapping them up.

Ah, so am I wrong thinking they can be put in a pot of mix of compost and soil and kept in a sheltered environment, eg in our shed? Do they definitely need to be dried out rather than kept in soil?

I have followed the RHS instructions for my dahlias which was to store them in dry potting compost in my unseated garage - having washed all the soil off the roots and then dried them upside down in a pot first. It's my first year so I'm just crossing my fingers.

I keep my dahlias still in their pots, but in an unheated greenhouse. They die down completely and come back in the late spring. Taking them out of the pot and drying off is a way of saving space.

Ah, Mere thank you, I actually have a question about the environment best to store them.
I understand they need to be kept in a "frost free" environment, so you mentioned an unheated greenhouse.

I'm learning so bear with me!

Surely "frost free" means it never goes below 0°? So an outdoor greenhouse would fall below that temperature in winter.
Or does "frost free" basically mean, away from moisture in the winter but can cope with temperature below 0°?

Beware ah I just saw your post,
The tubers buried in dry compost stored in a garage is what I would like to do, but I don't have a garage.
I'm trying to work out if my outdoor sheltered space would be suitable I have a shed and a plastic not glass greenhouse, not sure if that's suitable?
Then I'll put them in dry compost or wrap them in screwed up paper.

Mine go in boxes with newspaper around them after being well dried out. Just keep them above freezing dry and dark. I also dust with a fungicide before they go into the loft and on boxing Day I will check to see if any have rotted and remove them to stop it spreading

I should say I was only refering to dahlias. I don't overwinter begonias.

Thank you wherehave

Mine are fine in the pots they spent the summer in - in a greenhouse. I made sure they dried out in the pots.

This year has been much wetter so I'll probably take them out of the pots, shake off the compost, and store in a shed. A couple of years ago they all ended up dumped in a trug in a big heap in the garage and were fine.

Keeping them dry is the key - and check them over the winter to make sure nothing has gone off.

The most important thing is to keep them dry and airy. Both the Dahlia tubers and begonia corms could rot if they are sitting in wet soil. With both these, I lay the on either dry soil, newspaper or shredded cardboard on a tray or a box. Don’t cover them up as the cold is no problem but damp air could be. As long as your garage is dry they will be fine. Brush off as much soil as you can, trim the top growth and they will be fine.
Mine are all sitting Amazon boxes .

You're right, frost free does mean above 0. Dahlias presumably can cope with a few degrees below (otherwise people wouldn't recommend a garage). My greenhouse is insulated with bubble wrap in the winter; it is above 0 during the day time, but will drop to about 2 degrees below some nights. I can switch on a heater if it's forecast to go below that. And the dahlias are in pots so have extra insulation from the soil.

On that basis your shed would be suitable, and your greenhouse if it's a sturdy polycarbonate one, but probably not if it's a tiny "starter" greenhouse. The most important thing is to keep them dry. There's even cacti that can live outside in the winter as long as they are kept bone dry and sheltered from the rain.