If you grow according to the season then vegetable cultivation becomes a breeze because your plants thrive when given the conditions they love. If you live in a warm climate there are many varieties you can grow in the ground year round, so February is a great time for sowing seeds outdoors to boost what you've already got going on.
If you live in a cold climate with a short growing season it's best to grow seeds under cover and transplant the seedlings outdoors after your last frost date. This will definitely give you a head start on the growing season. Alternatively sow them in the ground on warm and sunny days when the soil has warmed up but have good protection on hand to cosset your seedlings if a cold snap is on the way.
