Growing Avocados

While avocados are a tropical fruit more suited to the humid regions of Mexico and Central America, it doesn’t mean they can not be grown successfully in the UK. The trees can grow to up to 20m and can take up to 10 years to fruit.

If you want to grow an avocado tree, it’s best to raise it as an indoor plant. The trees don’t tolerate freezing temperatures. They can grow outside in the far south of England, and have even grown fruit in some years, but you’ll get better results if they’re grown in large pots indoors.

Germinating the Seed

Avocado stones take a long time to germinate. If you already have a garden and a compost heap, you may have noticed avocado stones germinating inside the heap. This is because the heap provides the ideal hot and moist conditions for germination. There are alternative methods, however, if you don’t fancy rooting around your compost heap:

• pierce the seed with toothpicks and suspend it, pointed end up, over a glass of water. Roots should start to develop within two to six weeks. Then pot up the plant, leaving the tip just poking out of the soil. However, not all avocado seeds will germinate, so if your seed hasn't sprouted after six weeks, try again with a fresh seed
• leave the seed in direct sunlight until it starts to split. Then pot it up
• place the seed in a pot, and cover it completely. Water well, allow to drain and leave in a warm, dark place, such as an airing cupboard. Check on the pot every week to ensure it is moist, and water if necessary. As soon as the shoot starts to show, move the pot to a sunny spot, such as a windowsill

Always use a pot with approximately a 12cm diameter. Use a rich, peat-free potting compost and ensure the pot has good drainage. After your plant is roughly 30cm tall, cut it down to around 15cm. This makes the plant grow bushy, rather than tall. Once your plant has filled its pot with roots, transplant it to its permanent home – the largest pot you have room for. Fill with rich, peat-free compost, which you should top up with fresh compost each year.

Flowering and Pollination

Avocado trees can take up to ten years to bear fruit and indoor-grown plants don’t always live that long. However, if you provide it with a moist, fertile soil and plenty of sunlight, and keep it in humid conditions such as a greenhouse or conservatory, your tree will have a fighting chance of fruiting.

An old gardeners’ trick in the southern hemisphere to encourage the plant to flower is to treat the tree roughly. When it is of a decent size, (no smaller than 1.5m), attack the trunk of the tree with a knife, or sharp implement. Make sure you don’t damage the tree so it can’t grow properly, and only cut the surface of the bark – never make big cuts in it. The stress brought on by this attack is said to shock the plant into flower, where it will then hopefully bear fruit.

If the plant is indoors and it flowers you will need to pollinate them in order for it to fruit. Keep a window or door in the greenhouse or conservatory open to let bees in to pollinate it, or move the plant outside – if you can – on sunny warm days.

Regardless of region, avocados are not easy fruits to grow. However, the trees make an interesting addition to the conservatory or greenhouse and you’ll never tire of trying to make it flower. If you are lucky enough to get it to bear fruit you’ll be rewarded with delicious, fresh avocados and all your hard effort will be worth it.