Though it's still too cold to direct sow seeds outside, there are plenty that you can start off inside in February. A propagator is ideal if you have one, though a warm, bright windowsill is fine, too.
By sowing seeds early on in the year, you can be enjoying beautiful blooms and tasty crops for a larger part of the year. The season of interest can then be extended by carrying out repeated sowings from March onwards.
Cosmos are easy flowers to grow, and they look great in borders or meadows. Go for annuals like Cosmos bipinnatus or C. sulphureus, and choose single-flowered varieties like 'Fizzy Pink' to please pollinators. The seeds need light to germinate, so sow on top of seed compost in a tray, then prick out when large enough to handle.
While very hardy, kale seeds need to be started off indoors during winter, as it will be too cool outside. Sow them indoors in modules or 7cm pots, with 2-3 seeds per module, then thin to leave the healthiest seedling.
Salvias, like this Salvia patens, are great for providing structure and height in the garden, and can be grown in borders or containers. Sow the seeds under cover in February, on top of seed compost. Cover the seeds with a fine layer of compost, then grow in a light, warm spot, keeping the compost moist. Other salvias you could sow in February include Salvia splendens and Salvia farinacea.