Upcycling for the Garden
When cafes and roasteries turn raw coffee beans into the drink we know and love, there are a number of byproducts produced that often go to waste or end up in landfills. Thankfully, pretty much all of these byproducts are compostable, recyclable or upcyclable.
From the coffee husks left after roasting and coffee grounds after extraction, even the burlap/jute sacks the coffee beans travel in. All of it is actually an organic matter, produced organically, that breaks down into simple compounds that go towards enriching the earth it is given back to.
Any budding green-thumbed pixie should ask themselves: how can I repurpose resources that are readily available, instead of adding to the city's swelling landfills? Well… We have a few ways you can get more life out of coffee byproducts, even for small gardens.
Coffee suits your garden, down to the ground
Spent coffee grounds are a useful addition to your garden, especially for making rich compost, as they have a similar nitrogen to carbon ratio as manure. This will give your garden an extra boost of energy, which is appreciated by most plants (especially leafy green crops such as lettuce, corn et cetera), and it is a major fuel for microorganisms that help breakdown organic matter to form compost. When combined with a carbon source (e.g. fallen leaves, straw, newspaper et cetera) this provides good levels of phosphorus and potassium too. In fact, it is possible to make a complete, nutrient-rich compost by using just coffee grounds, shredded newspaper and a bit of kitchen waste.
Have a worm farm? Give them some spent coffee grounds to chew on, they'll love it and it will help improve soil structure by aerating the soil and creating micropores for water to infiltrate, and make nutrients readily available to plant roots.
Spent coffee grounds are rumoured to deter snails and slugs. They don't like the texture or aroma - so sprinkle some around crops like lettuce, strawberry plants, cabbage etc. to keep them relatively slug and hole-free! There is also a theory that cats don't like the smell either so you could try using it to stop those naughty little kitty cats digging up your newly planted beds.
A common misconception is that grounds are acidic and good for plants that prefer more acidic soil. However, most the acidity is water soluble and ends up in your drink rather than the grounds, which have a pH level close to neutral.
Coffee husks puts the fibre back into your garden's diet
Underground Coffee Roasters roastery in Christchurch produces copious amounts of coffee husks also known as chaff from roasting the green beans, this is a byproduct that can be used as mulch to conserve water and suppress weeds - the key is to lay it out on a still day and water it in so that it doesn't just all blow away (or use it in a glass house). These husks are rich in nitrogen and potassium, as well as cellulose and other organic matter that soil life thrives on. It can also be used as a soil conditioner by simply digging it in before sowing.
Coffee grounds are available from most Underground cafés, while husks/chaff are available from Underground's HQ only.
Sack up and get growing
Burlap and jute sacks are great for growing vegetables, herbs and even small trees in - they provide good drainage and are made of natural fibres, so they break down over time. This means you could later plant the plant, sack and all, in the ground, with no transplant shock to the plant.
Coffee sacks also make great weed mats for pathways (newspaper or cardboard underneath will help suppress weeds even more) or use them as a dry mulch to prevent strawberries, cucumbers, pumpkins et cetera from rotting on the ground.
Even if you have very little space outside, you could still grow potatoes in a few sacks on a porch so long as it gets at least 4-5 hours of sun a day. There's practically nothing to it! Throw about a foot of dirt (and maybe some spent coffee grinds as compost) into rolled up sacks, plonk your seed potatoes just under the soil surface, and water them thoroughly about once a week or fortnight (depending on how dry it is). Then you just sit back and watch them grow! Occasionally unroll the sack and add more soil, i.e. when your shoots get leggy, usually 2-3 times suffices. The main thing is to only expose the leaves to the sun, this ensures that you won't get green potatoes, which are the less tasty and more toxic variety!
Drainage can be further improved by keeping sacks on a pallet or over gravel, and by using soil that is not too clayey. Clay particles and water molecules can get locked in an eternal embrace which leaves out oxygen, so the roots cannot breathe.
If given a bit of TLC every so often you should get a pretty good haul of home grown tasty potatoes in each sack. Just rip it open and harvest your spoils!
Sacks are available from Underground Coffee Roasters, 190 Durham St Sth, Christchurch, for gold koha. All proceeds go to Christchurch City Mission.