Each plant's particular needs will determine when it should be set out in your garden. From the earliest spring days for peas to the long hot summer weather that ripen tomatoes, time your garden-planting schedule carefully to get the most out of your harvest.
Before Last Frost
Many warm weather-loving plants, such as tomatoes and peppers, need an extra-long time to grow in northern climates. There is not enough time for many gardeners to grow these tender vegetables from seeds directly sown in the garden. These plants must be started inside, then transplanted after they have been growing for almost two months. This head start in the season allows the plants to achieve their best growth in the warm middle of summer, which helps to ripen mid-season vegetables.
Plant cool-weather vegetables like lettuce, peas and spinach as soon as the chance of frost has passed in the spring. Find the average last frost date from your local extension service or by checking in Farmers' Almanac. Make sure that the soil has drained well before planting these seeds. One good way to check this is by squeezing a handful of earth. If you can flick the dirt apart like chocolate cake, your garden soil is ready to be planted. If the mud sticks together like clay, wait another week before testing it again.
Before First Frost
Savvy gardeners know that if a plant does well in the cool spring, it can do even better in the fall. The ground is already warmed up, giving seeds a bit of a head start, while the cool air that these plants love is already appearing at night and will soon take over the days. Get these seeds in the ground so that their main growing time is after the worst of summer's heat. You can snip lettuce and pick broccoli until the frost comes to end your gardening for the year.