Can coffee perk up your garden?

Even in these cash-strapped times, we’re not giving up our daily lattes and state of the art coffee machines.

So what can we do with all of those used coffee grounds? Apparently we can use them on our gardens.

A recycled coffee fertiliser has gone on sale at Notcutts (£9.99 for a 5L tub), and even Starbucks is giving away used coffee grounds for free.

I’ve long been familiar with the idea of putting coffee around plants to deter slugs (they don’t like the grainy nature of them, and they find the caffeine toxic), but had never heard of coffee being used to enrich soil.

How fertile is left over coffee?

I asked Guy Barter, chief horticultural adviser at the RHS, whether he thinks it’s worth us adding coffee to our soil or compost heaps:

‘It’s always nice to add fertility by using waste materials. A sprinkling [of coffee grounds] in conjunction with manure or compost should be fine. We’re talking very low levels of nutrients, but cumulatively added organic matter builds up and the nutrient addition is worthwhile.’

So there you have it – adding coffee grounds can only benefit your soil. The jury’s out on whether they deter slugs, though – when we trialled slug and snail deterrents at Which? Gardening we found that the coffee is too easily washed away by rain, and so it needs to be topped up regularly.

We also found that tea leaves are best put on the compost heap, rather than around your plants. Back in 2010, we looked at some old wives’ tales and found that it’s unlikely that much of the nitrogen in tea is actually available to plants.

Tea also contains aluminium, fluorine and manganese, which are harmless to people but high concentrations in very strong or stewed tea could stunt plant growth.

But, as with lots of gardening ideas, it’s a case of what works for you. What do you throw on to your compost heap or place around your plants?