HT Games
Wyson the Gardener
You'll find Wyson in Falador Park, where he is the head gardener. He can sell you woad leaves. If you offer him 10 coins or fewer, he will reject your offer; however, if you offer him 20 coins, he'll reward your generosity by giving you two woad leaves for this price instead of just one.
Woad Seeds
If you have a pay-to-play membership, you can grow your own woad leaves from seed. You will need Level 25 Farming or higher. You can obtain woad seeds via the Grand Exchange for a few coins, by picking Master Farmers pocket if your Thieving skill is high enough, or as a rare monster drop from tortoises. Look for Master Farmers in Draynor Village, in Hemenster, to the north of East Ardougne and the south of Varrock.
Growing Woad
Once you have acquired a woad seed, you will need to plant it in a flower patch. You can find flower patches north of Catherby, south of Falador, in Hemenster and in Port Phasmatys. Plant the woad seed in the flower patch, where it will take around 20 minutes to grow. When mature, it will produce three woad leaves.
Dyes
Woad by itself makes a blue dye. With red berries, you can use it to make a purple dye; with onions, you can make a green dye. Bring your woad leaves and other ingredients to the witch Aggie in Draynor Village. For five coins, she will convert the ingredients into a small amount of dye.