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This is a dragon fruit, also known as pitaya or pitahaya. It is called dragon fruit because it has scales in the outside and has brilliant colours. They can be red skinned with white flesh, red skinned with red flesh or yellow skinned with white flesh. Dragon fruit does not grow from a tree, but from a cactus. Thus by growing dragon fruit seeds you will get cacti.
The particular type I used is red-red. Dragon fruit is not very tasty, you should not eat it with strong tasting foods. I found it very good, despite this.
To eat your dragon fruit, cut in half and eat the flesh with a spoon. The flesh is full of seeds, like a kiwi, and these are the seeds you need to get a dragon cactus. From a spoon of dragon flesh you can get plenty of seeds, more than you will need.
Dragon seeds have a high germination rate, with just 15 or 20 you can grow as many dragon cacti as you want. After eating your dragon fruit, you will probably leave a little flesh and seeds close to the skin of the fruit. Remove it with a spoon, and clean with water to remove as much flesh as you can.
The next step is really boring. Pick a paper napkin or something similar and one seed. Press it with your finger against the paper towel, rubbing it. Repeat until there is no flesh left around the seed.
Keep repeating until you have enough seeds. An interesting fact is that when these seeds sprout, they develop a hairy root which adheres to the substrate. This means that sprouting them with the paper tower method can be hard: when you have to remove the seeds, you have to pick also the paper, they are strongly attached to it.
I had better results by sprouting them in a glass with wet cotton. They will start sprouting in 3 or 4 days, and start developing two leaves, which will disappear as the cactus grows.
Earth day give-away project: lemon trees from seed to save the planet
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