Tea Bag Index experiment - pairs of tea bags for planting

On Thursday I pottered out into the garden and planted some tea bags. This isn’t because I have some loony idea that they’ll grow into tea plants* (you were wondering that, weren’t you?) – it’s all in the name of soil science.

The Tea Bag Index is a world-wide investigation into the health of our soils, and the effect different types of management have on it. It measures decomposition and standardizes the variables by looking at the degradation of buried tea bags. So far very little data has been collected in the UK, and this year the project aims to work with gardeners across the UK to compile a Tea Bag Index database.

“Using this information I hope to find out how decomposition varies across the country, and whether it is influenced by how gardeners manage their soil, particularly with respect to the application of compost.”

As an organic gardener and a Master Composter, you’ve got to believe that I am going to be interested in those results!

When I signed up for the project I was sent three pairs of rooibos tea bags, attached to labeled sticks. The idea is to plant each pair in different areas of the garden, with different plant cover and management strategies.

Tea Bag Index: Site A after planting

I planted my ‘A’ pair in one of the areas of the garden we haven’t done anything with yet. It’s very close to one of the new raised beds, as I wanted it to be out of the way. It’s in a patch of what we will loosely call ‘lawn’ – one of the remnants of badly compacted, very weedy grass that used to cover the back garden. It was horrible to dig, hard and stony.

Tea Bag Index, bags 'planted' in Site B

I wanted to put my ‘B’ pair in one of my raised beds, but thought better of it. They’re entirely filled with a soil mix I made from bagged topsoil, manure and peat-free compost. They sit directly on the soil, but it’s a long way down. Whilst it would tell me something interesting about what’s happening in my raised beds (where some well-fed plants are growing very large), it wouldn’t tell the survey anything useful about my soil. So instead a picked one of the new raised beds in the Sunset Strip area of the garden, which is currently planted with a Shark’s Fin Melon (Cucurbita ficifolia) that, rather excitingly, now looks like it has established nicely. I did put some manure on this bed before planting, and the squash is planted into a mound of topsoil and peat-free compost, but the tea bags are buried under a section that is just manure and the natural soil. Still, it was easier to dig than the first one.

Tea Bag Index: Site C after planting

And I placed the ‘C’ pair in the front garden. It has been dug over and planted this year, and received a bark chip mulch, but I didn’t add any other amendments to the soil. It was far easy to bury the tea bags in this environment. Last year this area was lawn, which we killed off with weed control fabric, and it was a far better lawn than the back garden. I do need to get out there and do a little bit of weeding, but so far the new plantings seem to have settled in nicely. The two Buddleja Buzz plants are just about to flower. The Chilean Guavas have been doing that, in their more subtle fashion, for a while now.

Once three months have past I have to dig up the tea bag pairs, dry them out and send them off for analysis, but in the meantime all I have to do is wait. Anyone fancy a cuppa? 😉

*I did try James Wong’s suggestion to sow the contents of a chamomile tea bag to get chamomile plants. It didn’t work for me. Twice. James says the age of the tea bag isn’t important. Since I don’t like chamomile tea, I think ours may have been too old. I use them to make chamomile tea to prevent damping off disease in seedlings 🙂

James says that fresh chamomile tea is nothing like the dried stuff in the tea bags, and is much nicer. I do have a chamomile plant in one of my herb planters; at some point I will be brave enough to try that theory out!