Prepare your propagator by adding the recommended quantity of seed-sowing compost. Plant your seeds in accordance with the instructions on the packet before watering in and covering them with the propagator lid. Place your propagator in a warm location like a windowsill, keep the compost moist, and wait for your seeds to germinate. Once the seedlings are established, thin them to encourage larger seedlings, which you will later plant into pots once the first true leaves have developed.