Even large trees can be kept to a manageable size when planted in a container, and they are easy to grow from seeds you can find for free when walking in the park. In autumn, look out for conkers from horse chestnuts, acorns from oaks, and sycamore seeds, all of which will germinate in a few months.

When to plant: Autumn.

At their best: Spring to autumn.

Time to complete: 30 minutes.

You will need: Tree seeds (you can use a conker from a horse chestnut tree for example), plant pot, broken clay pot pieces, soil-based potting mix, trowel.

Prepare to plant

Check that your seeds are firm and have no holes or other signs of insect larvae inside. Place some clay pieces at the bottom of the pot, and nearly fill it with soil.

Plant your seeds

Plant the conker about 1 in (2 cm) deep, and cover with soil. Water, and place in a shady spot outside. Check that the soil doesn’t dry out. Your seed will sprout in spring.

Other seeds to try

It’s worth planting a range of tree seeds, just in case some do not germinate. Collect seeds when they are ripe—undamaged seeds that have fallen to the ground will be at the right stage—and plant them immediately, since they dehydrate quickly if they are stored.

Easy to grow

Collect ripe acorns, hazelnuts, crab apples, eating apples, and cherries, either from the park or from your own or a friend’s garden. Remove the flesh from the fruits and wash the seeds first before sowing. Many tree seeds require a period of cold, or even frost, before they will germinate, so leave your pots outside where they won’t get blown over.