Trim off and discard leaves. Wash stalks; cut into pieces about 3 cm (1 inch) in size. This is a rough guide; no need to be exact.
Measure out by volume how much rhubarb you have, and place into large pot off the heat.
For each litre / quart volume (400 g / ¾ pound weight) of rhubarb you have placed in the pot, add about 100 g (½ cup) of sugar. [You do not have to be precise down to the micron: the key control factors for safety here are acidity and heat processing.]
Stir sugar in, let pot stand off the heat.
When some juice has appeared, put pot on stove over medium-heat, stirring frequently, and raising heat as more juice appears.
Heat the mixture slowly to a boil.
When it is boiling, the rhubarb will have been heated enough for packing. Don't cook it past that. You want stewed rhubarb pieces, not syrup.
Pack the boiling hot rhubarb into ready jars, trying to ensure that each scoop has a roughly equivalent amount of solids and juice.
Leave 2 cm (½ inch) headspace.
Debubble, adjust headspace.
Wipe jar rims.
Put lids on.
Process in a water bath or steam canner .
Process either half-litre (US pint) or litre (US quart) jars for 15 minutes. Increase time as needed for your altitude.