I must point out that understanding a vegetable that is said to be good to a certain zone...means it can be relied on to do well in that zone....if planted in the garden...in the soil.
Its not a gurantee it can do as well in a container.

First off the container has limited volume of soil and the roots must be able to draw from the soil what nutrition it is used to create the flowers and leaves.
Since rhubard has so large a leaf I would hazard a guess that it is not a good candidate for container growing.
Secondly, how is one to winter over such a vegetable...as large a root ball as it will have.
To winter over any containerized plant where winters are severe...cold, snow, freezes, thaws, freezes....rains, cold, snow, freezes....
how can a container plant take all that and be expected to come back in the spring.

The usual recommendation is to put it somehwere where it can be given protection, yet at the same time, be given water to keep the roots alive.
Or.....bury it! Open a trench and put the whole container in and bury it under soil or leaves or mulch....anything to keep it viable.
If this is not possible, then plnat it in the garden.

Rhubarb is a vegetable and should be given its own space...it should not be rotated like other vegetables..especially tomatoes.
Did I understand you to say that you put strawberries and rhubarb in the same container.

Its not a good idea to put any two vegetables...or plants...in the same container unless they have the same attributes...can be watered the same, can be given fertilizer the same, can be given sunlight the same....
otherwise, one does better than the other and if given the same treatment, one will do poorly and may, if it causes disease or a fungus, will certainly affect the other.

I suggest you put the rhubarb plant into the garden and let it produce the shoots properly......but
Rhubarb should have the flower stalks removed as they come the first year.. During the first year stalks should not be picked since food produced from the leaves is needed to nourish the roots for the next year's growth.

A light picking might be taken the year next if the plants are vigorous.
When harvesting rhubarb, the first step is to cut the stalks at the soil line or simply pull each one out independently.
All of the stalks of a plant may be harvested at that time or pulled out over a three to six week period.

Dont leave the fruit not longed picked, otherwise it will just go to seed.
After the stalks are cut, the leaves may be removed.
The leaves are poisonousÂand a tea can be made from them that can be used as a spray on bugs.

If you go ahead and give the rhubarb a place in the garden, manure is a great food. Buy sheep manure at your local garden center or nursery. It will be a well composted bag.
Otherwise, any good compost can be used.

Aphids still might be a problem on the leaves if you don't remove them. Trounce...an insecticidal soap can be applied.
Its a little late but maybe you can find a praying mantis in your garden..(I did the other day, almost ran over it with the mower) or ladybug.

If the plant appears weak when growing, superphosphate 0/20/0 can be given. About a tablespoon mixed well into the soil and watered in.

You cant leave the container out through a winter...the soil would certainly freeze solid and the roots with it.
If you try to keep it outside, then try to winterize it by covering with aluminum foil to ward off sunlight.
Wrap it in burlap and/or put cardboard around it, tied, then wrap it in aluminum foil.
Raise it off the ground which will freeze. Air can be then allowed to pass under it. Rain/and/or snow, will run away from under it.
Put it into a protected area, against a wall, in amongst your foundation plants, cover it with evergreens.
Snow cover will do the rest.

But I suggest instead give it a place in the garden, remove the leaves and let it be.

Jeannie, thanks for your prompt response! Just to clarify, the rhubarb and strawberry plants are not in the same pot. Also, I should have mentioned that these pots are on the porch, so they would be exposed to cold, but not snow/rain.

If I had a place to put the rhubarb in the ground I would, but the only reason I took it home from the swap, was that another gardener had successfully overwintered her container of rhubard, so I thought it would be worth a try. As you can see in this photo, the pot is quite large, and the plant was happy until a week or two ago. I've had it since May.

{{gwi:46146}}

I was under the impression that if a plant was hardy to a zone or two colder than my actual zone, that it had a good chance of surviving the winter in a container. So would these plants have a better chance of survival in the unheated garage, or should I leave them on the porch?

Bonnie

The pot...I'm guessing to be about 10"..and plastic.
I mistrust plastic because it holds moisture longer than I think it should. In any case, if I'm right, it being 10"..it is too small to contain such a volume of roots that the vegetable will grow.
Considering there must be soil below the roots to properly feed nutrition to, and allow good drainage, 10" is not all that well for growth.
I think 12" is minimum....but bigger would be better.
Have you considered one of those larger wooden patio containers...18" across...the same in depth. Wood will absorb some watering, it is not a conductor of cold...or heat.
It should be nevertheless raised off the floor where you intend putting it to better let the drainage run away and not freeze. A couple of bricks could be placed under it.

If as you say the garage can be maintained at higher than freezing, the container would be able to be used.
Its tough tho to hold a temperature above freezing if the ambient temperature outside is well below freezing and you open the large door of the garage for any length of time.
Cold winds can do as much freezing of soil as the air above it.
Wrapping---say with cardboard, would protect it somewhat.
Burlap around that I think would insulate well.
If your garage is attached to the house, the wall it shares with the house will be, on average, 5º higher than the ambient temperature elsewhere in the garage.
Such container near the wall could be thought to be slightly milder than the other parts of the garage.
I say this because sometimes plants are put on shelves next to such wall and benefit from being next to it.

What the heck, you can try it...if it works, you have an idea to have it work again next year. If not, then you get a lesson in how not to grow a vegetable of such size.

I wouldn't move it though until after the first frost to ensure it does go dormant.

Hi, HAT. Rhubarb grows in Siberia, and will overwinter in a container in zone 5 w/o protection. Your garage is fine - no temperature worries - as long as you don't let it (the planting) go completely dry.

What have you done in the way of nutritional supplementation for the planting? Some generalities: If leaves on the outside of the clump were predominantly the yellow ones, it's likely that the roots are too tight and the plant needs a bigger pot or dividing. If the center leaves or the entire plant are yellowing evenly, it's likely from over or under-watering. This is with the consideration that nutritional needs are being adequately met. There really isn't enough information in your post for anyone to offer anything other than a general response.

The pictures indicate you have something fungal going on. Are you wetting the foliage when you water? You might want to do a search using the words rhubarb, Ascochyta, and Ramularia. When you do, you will also find discussion of types of crown rot, which can occur from planting too deep or wetting the crown when you water.

Strawberries can be over-wintered in your garage by setting the container on the floor and covering loosely with an overturned cardboard box. It will trap geothermal heat rising through the garage floor while still allowing enough air circulation to prevent fungal issues.

Al

Al, I had thought that rhubarb was a northern vegetable, so thank you for confirming my belief that it will successfully overwinter here.

The only nutritional supplementation, other than what was in the potting mix, was one application of fish emulsion.

I did a search for the fungi that you mentioned, but the desriptions don't quite match with what I'm seeing. The yellowing is occuring on only the outside leaves. The pot measures 14" across, and 12 inches tall. As big as the roots were when I planted it (the size of large carrots!), I would not be surprised if it has outgrown the pot. I will try and find a larger one, and transplant it once the weather cools down a bit, and see if that helps.

On the strawberries, should I let the plant die back before bringing it into the garage? Also, what should I do about the runners it is sending out?

Bonnie

Rhubarb is a heavy feeder, so it will respond well to regular applications of fertilizer in the 3:1:2 ratio (like 24-8-16 or 12-4-8) or alternately 1:1:1 ratios (like 20-20-20). I didn't read through the whole thread, so I don't know if your want is to remain organic in your supplemental nutrition program, but the plant will respond much faster to the soluble fertilizers like MG and others.

N deficiencies manifest themselves in the yellowing of older leaves first, so that could be what you're seeing in the yellowing of perimeter leaves if it is not from crowding. You should plan on dividing the plant early each spring if you plan to keep in a container.

It won't hurt the strawberries to go through a light freeze or two, but bring them in before temps drop below 25* - the roots will not tolerate extreme cold, which is why you'll always find them mulched with straw (field grown) in zones 5-6. It also helps guard against dessication. BTW - you'll only need the box during the very coldest days & only if the door is left open.

Good luck. ;o)

Al

Al, thank you for the helpful information!

I have stayed organic with lawn care, and in the flower and veggie gardens, but I had a maggot incident using organic fertilizer in an Earthbox, so now I am willing to forego the organic fertilizers in containers : )