Planet growth rate

[Groth]

How complex is the mechanic for the population rate ? Is the growth rate linear or exponential ?
For example would it be better to colonize as fast as you can as long as you have the minimum population left on your homeword or would it be better if you wait until your planet has almost maximum population and then colonize a single planet, wait again for max, colonize again and so on?
I think its one of the most important questions regarding a good start in the games. Do you colonize 2-3 in a row or wait until you have again 2.9 or 3 of your 3 max. pop. on your homeworld.

[Lucas]

Growth is linear, but based on the level of the planet. The higher the planet level, the faster it grows.

[Groth]

Thanks for the quick answer.