The University of Minnesota Extension's information sheet on rhubarb (https://www.extension.umn.edu/garden/yard-garden/vegetables/growing-rhubarb-and-sorrel-in-minnesota-...) states the following:

'Rhubarb plants are very large; fortunately, a single plant usually provides enough for any family. Each plant should be allowed a three-foot by three-foot area in the garden. For most gardeners, it's most convenient to position rhubarb at the edge of the garden. It should be in a spot that receives all-day sun. Rhubarb is hardy in USDA Zone 4, and worth trying in Zone 3."

In the Cornell University's Vegetable Growing Guide on rhubarb, (http://www.gardening.cornell.edu/homegardening/scenec4d4.html) it suggests horseradish as a good companion crop with rhubarb since both are long-lived perennials.

Based on the article form Michigan State University Extension titled "Cool" Vegetables for you to Grow this Spring",
 (http://msue.anr.msu.edu/news/cool_vegetables_for_you_to_grow_this_spring) it appears that there are no restrictions in growing rhubarb with other vegetables assuming they all have similar growing condition. It states the following:

"This is also a great time to make plans for companion planting and different layers of your vegetable garden. Seed radishes and beets along with your lettuce. The shallow-rooted lettuce will grow near the soil’s surface while the radishes and beets will push down into the soil. These root crops will naturally break up the soil, adding air and water space. Plant roots will provide a place for necessary soil microbes to live. Place onion sets among your greens for the same effect. If your greens die back or bolt, you can reseed another crop while allowing the root crop to fully mature.

Take advantage of the vining habit of peas to plant them amidst a ground cover of greens. Provide upright support for your peas via a trellis while lettuce or spinach help to shade and cool the roots of the peas and ward off weed seeds. Pea seeds can even be planted in a spring porch container along with cold-loving pansies or snapdragons.

Consider incorporating some perennial vegetables such as asparagus and rhubarb. These crops will take more room and a permanent location, but once established and successfully managed, they will continue to provide fresh asparagus spears and rhubarb stalks. Choose a well-drained location for each and mix in organic matter such as compost to prepare the soil. Once plants are established, adding composted material annually around the base of the plants will continue to be a smart practice to build healthy soils."

I hope this information has been helpful to you.

There is an additional source that I thought would be helpful to you. The Rhubarb-Central.com's article on Rhubarb Companion Gardening (http://www.rhubarb-central.com/companion-gardening.html)

Rhubarb Companion Gardening

What Garden Companions
to Grow with Rhubarb

Looking for Rhubarb Companion Gardening ideas?

My experience with growing rhubarb is that it grows very well alongside almost any garden vegetables and flowers, but there are a few points to consider in this regard.

Here are a tips suggesting a few plants that should not be planted near rhubarb, and several suggestions of plants that are favourable/helpful to grow alongside rhubarb in the home garden.

Gardening with Plant Companions is a great concept, by which, with careful planning, you can "help plants help each other" by choosing which garden companions to grow together.

In some cases this method of planting can help attract "helpful" bugs or repel "harmful" bugs.

In other instances particular types of plants may be planted to assist other plants by the natural addition of nutrients into the soil.

There are claims that companion planting helps to improve plant growth, plant health, and food flavour. Even planting certain larger leaf plants, (for example, rhubarb), can assist other, more sun sensitive plants by providing shelter from the sun.

Members of the Brassica family such as broccoli, kale, cabbage and cauliflower are also good companions for rhubarb, but rhubarb really does not require specific garden companions. In fact, our rhubarb garden is just that...a rhubarb garden, with no other vegetables or other plants, and it thrives amazingly!

One visitor to Rhubarb Central.com offers this advice: "Whilst rhubarb doesn't really need companion plants, strawberries are in fact a fantastic companion plant for rhubarb and the relationship is very much reciprocal."

Some gardeners claim that rhubarb should not be planted near legumes, because legumes may attract the tarnished plant bug, which can become a rhubarb pest.

One weed, which does adversely affect rhubarb is Dock Weed Plants.

Dock Weeds, (see the pictures below), are perennial weeds and a member of the Buckwheat Family growing 0.8 to 1.5 metres tall.

These weeds have a deep penetrating yellow taproot; dark green leaves that are wavy and crisp along the margins.

Dock Weeds turn a rusty-red colour when mature.

These weeds attract a bug called the "Rhubarb Curculio", a yellowish beetle that bores into rhubarb stalks.

If you find a jelly-like, clear substance (see image above) on your rhubarb stalks, you most likely have had this pest visit your rhubarb patch. For more information about this rhubarb pest,

GO to Rhubarb Pests - Rhubarb Curculio

Some sources claim that rhubarb plants protect beans, peas, and other legumes against the black fly, and deters spider mites from columbine flowers. I personally have not had the opportunity to test these theories."