Tutorial: How to paint a watercolour cactus

Cacti are wonderful to paint in watercolour. They’re super simple – just long ovals stacked on top of each other. Make use of white space to create the effect of sunlight, and use a small brush for the spines.


What you will need

  • Watercolour paints
  • Watercolour paper
  • A brush
  • Water jars
  • Paper towel


  • Sap Green
  • Hooker’s Green

All the watercolour paint I use is from Winsor & Newton. Don’t worry if you don’t have these exact colours – just find the closest match in your palette.

You’ll need a mid-green tone for the cactus, and a darker green for the spikes. If you don’t have a darker colour, mix one by adding a dark blue or black to your green.

Paint a cactus – step by step

  1. If you want to sketch the cactus shape first, start with a large oval shape. Add smaller ovals on top, creating two sides. Vary the shape and size, getting smaller as you go up. Try not to make the shape too neat or symmetrical – you’re aiming for a random, organic shape. Choose one side to face the light source – this will contain the highlights.
  2. Mix up a light wash of green and fill the first big shape of the watercolour cactus. Leave white space on the highlight side. Add darker pigment to the shadow side in an arc, to create a three-dimensional shape.
  3. Continue adding the shapes, working on alternate sides. Let areas of darker pigment bleed into each other as you work. Allow the first layer to dry.
  4. To paint the cactus spines, mix up a dark green. Choose a fine brush to keep the lines thin, and use a flicking action to create the shape. Add the spines in a diagonal direction to avoid creating lines across the cactus, and switch up the direction of the spines. Make sure to add spines on top of the cactus edge too.

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