Between each primary and secondary on the 12-hue wheel there is one more hue: a tertiary color. Mix a primary with the secondary next to it and you get the color between them.
| Primary | + neighboring secondary | = tertiary |
|---|---|---|
| red | orange | red-orange |
| yellow | orange | yellow-orange |
| yellow | green | yellow-green |
| blue | green | blue-green |
| blue | violet | blue-violet |
| red | violet | red-violet |
Key idea
A tertiary is a primary mixed with the secondary beside it. By custom its name puts the primary first, joined by a hyphen: red-orange, blue-green, yellow-green.
Why it works
Each mixture sits halfway between its two parents on the wheel. Red-orange is redder than orange and more orange than red, so it lands between them. Naming the primary first is a convention that keeps the names consistent: red-orange, never "orange-red," in color-wheel talk.
Worked example: Make a tertiary
What do blue and green make, and where does it sit on the wheel?
- Blue is a primary; green is the secondary beside it.
- Their mixture is the tertiary between them.
- Primary first: blue-green.
Answer: Blue-green, between blue and green.
Common mistake
Two slips are common. One is naming the secondary first ("orange-red"). The other is mixing two colors that are not neighbors. Red and green sit across the wheel from each other, so they do not make a tertiary; they make a brown or gray (see Mixing Neutrals).