My Rhubarb Experiment

I seem to recall a discussion a while ago about growing rhubarb. If I remember right, @Zigs was showing off his excellent plants and remarked about them growing in or near some rubble or something. I mentioned how my dad had stopped growing rhubarb years ago because it was too invasive, and how prior to giving it up, whenever he started a new rhubarb bed, he would always mix in lots of broken bricks, stones, and whatever other junk he could find. His logic being that the hard obstacles for the roots forced the roots to fork this spreading the rhubarb.

Well, here's my experiment. I've bought two rhubarb plants. Both the same variety ('Victoria'), both from the same supplier on the same day.

Having got them home, I found two identical buckets (Morrisons 8 for £1 ones), and drilled 5 drain holes in each. Same drill bit (15mm) same arrangement.

I half filled each bucked with a mix of home made compost and soil, all dug from the same spot.

Then I found a load of broken bricks, smashed lumps of cement, stones, and a bit of rusty metal of unknown origin.

One is planted up with just soil and compost. The other has only half as much soil/compost mix, with the rubble making up the rest of the volume.

Here they are:



The stones on the surface of one of them are just there to remind me which is which. They're both going to be located next to each other with care taken to ensure they get the same warmth, sunlight, watering and feeding.

I don't expect too much to happen for the rest of this year now, but lets see what happens when they re-emerge next spring.

 

My "early" variety is still going strong.



Mines got a load of old lime mortar in the soil too.

 

Some early findings to report.

After just a week, I've noticed something very significant. Both plants are getting the same amount of water, but a few times I've caught one plant wilting a bit while the other has been fine throughout. The one that struggles is the one that does NOT have all the rubble in it.

So, contrary to my expectations, it seems that the one I expected would drain best, actually seems to be holding the water better. But, when watering, the one without the stones in it gets a puddle of water on the surface, whereas the stoney one does not. I keep the hose on them both for the same length of time with the rose set to fine shower mode.

 

Don't like being waterlogged then by the sounds of it

 

Dunno. I'm thinking the soil dries out quicker in the one without the rubble. It goes against what I'd have expected, but the wilting one picks up after watering, so it is as though that one is being deprived of water more than the one with the rubble in.

I'm reminded of my dad's theory, which is that the stones stimulate root development by causing the roots to fork when they hit an obstacle. A week isn't much time for significant growth, but I wonder if the roots are doing better in the stony one.

 

What kind of stones are you using, are they porous, permeable, impermeable ?

 

I definitely saw at least one lump of sand stone go in. The rest was smashed up pointless brick wall, so busted pieces of brick, some with cement on, and a few bits of cement from my last building effort. Set, mixed cement, the stuff I smashed off my trowel and bucket when I was done.

So I'd say mostly porous.

 

Ah ha, so the rubble is creating a reservoir.

 

I heard years ago, that the point of adding coarse grit to compost was to create a more fibrous root system, I do believe it works, but at the same time it stops the compost absorbing as much water, so drainage is better.
Compost also wets a lot easier once its dried out if it is "opened up" by adding some sharp material.
Not sure what kind of soil you used for potting up C1, but if it contained clay I can well imagine its wetting much easier in the pot with the rubble.

 

The soil is clay/loam, but I mixed in a good measure of compost in too. I mixed the soil and compost before sharing it out between the two plants, so as to be as sure as I could be that there were no significant soil differences between the two, other than the rubble or lack of.

 

Today I noticed that one of the two rhubarb plants has a strong new bud coming through. In the one without the rubble.

Still early days yet though. That could just be that the plant was more ready to do so even when it was in the bag/pot that it came in.

 

I almost forgot about this thread.

Anyway, an update. The one that was in the bucket with half rubble never bothered to come back. The one that is not in rubble is growing strongly.

Its not enough to draw any solid conclusions though. There were only 2 plants in the experiment, and it is possible that one was duff for reasons completely unrelated to the soil I gave it. I might pop along to the nursery and get half a dozen more soon, and repeat the experiment with a larger sample size.