How To Paint Cactus

• Software: GIMP (or any raster graphics editor)
• Level: Beginner
• Subject: Cactus

In this tutorial, you can have an in depth walk through of creating a digital painting of a cactus.

The final artwork would be as follows.

Without waiting further, let us start the editor with a large enough canvas size - a little larger than 480×640 pixels. Always start with a canvas larger than the final required resolution.

Draw a sketch of the basic shape of the cactus in a new layer. Use reference images if required.

Do not bother to add details. Just get the basic shape roughly. You do not need to have a clean line art either.

Next take a large brush, select a dark green color, and paint to fill the boundaries in a separate layer.

Do not worry if it goes out of the sketch boundaries.

Take a lighter color, more yellow than green and paint the area which is facing the light source - the sun.

Make a note of where the smudge and smoothen/convolve tool is in your tool panel.

Use those tools to get a smooth gradation. In digital painting, it is better if you do not use the gradient fill and paint the different colors and smudge the gradation yourself.

Now mark out the darker areas of the cactus - the area away from the sun.

Again, use the smudge and convolve tool to give it a cylindrical shape.

We will be adding detail to this basic form.

As you start to detail, you need to keep selecting the smaller brushes. Note that only normal round brushes of different sizes are used. Take a light yellow green color and draw the crease from top to bottom at the left edge of the main cactus stem. Draw similar lines, and every time choosing a darker shade of yellow green. This would serve as the highlight area, and as we move away from the light source, it becomes darker.

Does it look ugly? Do not worry - we will fix that soon.

Now take the same brush and a darker shade of green and draw lines adjacent to the lighter lines. The dark lines should be on the right side of the light lines, away from the light source. The light lines and the dark lines should be touching each other. The logic behind this is that wherever there is a bump up, one side would have highlight and the opposing side would have a shadow.

Note that I continue to draw the shadow lines on the dark side of cactus with an even darker shade of green. It is a very dark shade of green - it is not black. Avoid choosing a color from the edge of the palette. Avoid using absolute white or absolute black. You never know when you need to go a shade darker or a shade lighter.

Do the similar process with the smaller cactus appendages. Use a smaller brush if needed.

It is time to make it look less ugly.

Use your trusty smudge tool to blend the different colors. Now it looks like nice creases on the cactus surface.

Now that we are getting the basic shape of the cactus, and have made it recognizable, it would be time to loose the sketch. Before that, let us give it a little more definition.

Take a dark shade of green (not black) and with a small brush, mark out along the sketch lines. Try to have only a single line - confident strokes.

Switch off the sketch layer - make it invisible. Use your smudge tool over the dark outlines you had drawn.

It is time to clean the mess.

Select the eraser tool and remove the paint area that is outside the dark outline you had drawn. Use a soft edged eraser when you are cleaning near the edge.

We will visit the cactus again, to give it more detail. But before that, let us set some mood to the lonely cactus and give it some foreground and background elements.

Choose a range of colors from yellow-orange to yellow-brown. Paint the sand/mud in front of the cactus in a new layer. The places where it meets the cactus, carefully trace the creases of the cactus. This will further cue the viewers brain to think that it is a 3d form.

Paint a little more than I have shown above. After that, create another new layer - this time, behind the cactus layer.

In that layer, use the same set of colors, but with a bit lower saturation and paint the ground. Basic rules still apply - lighter shade near the source of light, darker shade away from the source of light.

It is time now to make the sand/mud to look more grainy instead of a smooth surface.

Use your paint brush, smudge, and convolve/blend tool and render a bumpy surface in the foreground. Leave the background as it is - as the object goes away from the viewer, the detials get blended together. Hence, we should not be detailing the background too much.

Use a small brush, and detail the hightlights and shadows casted by the small pebbly surface.

Use the blend/convolve tool and blend it a bit. Take a soft large brush, and in the background layer, draw the shadows casted by the cactus. This gives it the depth.

Create another background layer behind all other layers.

Paint the sky. Use different tones of desaturated blue, and with a large brush, paint the sky. Do not use a gradient.

Use smudge and blend tools to smoothen the sky.

For the next step, you can either choose to paint in a seperate layer, just above the sky layer, or paint it on the sky layer itself.

Take dark desaturated green and draw the faint shapes of the cactus that are far away. Use a soft edged brush. You do not need to give too much detail for the farther ones.

I did say, we will get back to our main cactus - did I not? Well, now is the time. Switch back to the main cactus layer.

Take a fine brush, and a very light yellow color and mark out the thorns using a single stroke. Like the creases, mark them out only on the lighter side of the cactus. The thorns are not to be drawn at random - they have a pattern. Now might be a good time to go back to any reference images you have started out with.
What applies for the creases, applies for the thorns too. Since we have drawn the highlight area of the thorns, we will now draw the shadow areas.

With the same brush, but a very dark brown color, draw the thorn. Zoom in if you need to. The strokes should be on the top-right side of the light colored strokes. Choose a darker color and draw the thorns in the shadow areas. Draw few thorns on the edges of the cactus.

You are done. Crop it and sign it.

Export it to whatever format your editor is compatible with.

Do post a link to the art you created in the comment section. Or use it to ask any questions you need to ask.

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