Grow your own ... from garbage!
  
For a fun bit of kitchen science, try re-growing food scraps that would normally go into the compost bin. This is definitely experimental horticulture—quick results are not guaranteed! But it’s fun to do and is a great way to talk about a variety of things such as recycling food waste and how plants grow.

Lettuce, bok choi, cabbage & celery


Place the base in a bowl with a bit of water. Keep the bowl in bright but indirect light and mist the leaves with water every day. After a few days you should see new leaves starting to grow from the top, and new roots growing from the base.

When there are several new roots, you can pot up your new plant in a pot of compost or in the garden. Keep it watered and harvest the leaves when they are large enough.

Celery stalks are tricky to grow but celery leaf can be used as a delicious herb.

My husband is feeling smug, as his lettuce (the one on the right) is doing much better than mine. His trick? He trimmed a tiny bit off the bottom before putting it in water. Impressive, as he isn’t even a gardener!

Basil & coriander

You’ll need stems about 10cm (4in) long. Strip off the lower leaves from the stems and place the stems in half a glass of water. Keep the glass in bright but indirect light. Change the water every day. After a week or so you should see new roots at the base of the stems.

When the new roots are several inches long, transplant your herbs into a pot filled with potting compost. If you’re growing them to snip the leaves you can plant them quite closely--about 2.5cm (1in) apart. Keep them well watered and grow them on. Start harvesting leaves once the plants are growing strongly. 

I’ve never had much luck with basil but am trying again!

Pineapple


Some sites suggest rooting pineapple in water, but pineapple plants like good drainage and rot easily.

The proper way to propagate a pineapple is to cut the top off of your pineapple, strip away several of the lower leaves to expose some stem (see the science bit below about nodes), leave the stem to heal over for about a week and then pot it up into a free-draining compost.

Now be patient as if you are lucky enough to grow a pineapple it may take upwards of three years! BBC Gardeners World has an excellent how-to guide here

Avocado


This one takes me back to the 1970s!

Suspend your avocado pit in a shallow bowl of water so that the base of the pit is in contact with the water. Wait for roots and shoots to appear, and then plant up your new avocado tree.

If you want your tree to bear fruit, now build a very large conservatory as mature trees grow 40 feet tall. Luckily, avocado trees also make good houseplants.


More things to try:
  • Salad onions
  • Tops of beetroot (beet leaves are good in salads)
  • Carrot tops
  • Stalks of lemongrass
  • Potato
  • Sweet potato
  • Ginger
The science bit
When your plants sprout new roots, have a close look at where these roots are coming from. They won’t come from bits of bare stem—they will instead be coming from areas of the stem where leaves used to be.

Why is this? Plants grow from specific places along the stem called ‘nodes’. Cells responsible for growing structures like leaves and roots are concentrated in the nodes. Areas between the nodes (‘internodes’) contain different kinds of cells that just grow longer. When gardeners take cuttings, we are encouraging the plant to grow new roots from a node (that’s why we take cuttings ‘just below a node’).

Brambles and couch grass are good examples of plants growing both leaves and roots from nodes. If you pull up a bit of couch grass or find a branch of a bramble that has bent down from the parent plant and rooted into the ground, you will find long areas of bare runner or branch (the internodes) and then bits where there are both roots and leaves growing (the nodes).

Enough science—off you go to raid the fridge. Happy growing!

Text and photos by W Crowder 2020. Developed for Harbury Seed Share and Earthworms School Gardening Club.
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