Direct Sown=Seeds are placed directly into the garden bed and will remain there. Seeds started this way are more at the whims of the weather.
Transplant=Seeds are sown indoors under controlled conditions. Seeds started this way require more managing as you (the gardener) provide them with all the elements necessary for successful growth. These plants are later moved outdoors into the garden as a “transplant.”
Regardless if you will be transplanting or direct-sowing these are elements for successful seed starting:
Temperature: Vegetable seeds sprout at different temperatures: Check out this basic chart. Soil temperature is generally 5-10 degrees F cooler than air temperature.
Notice from the chart that Muskmelon’s optimum soil temperature is 90 degrees Fahrenheit, while Lettuce is 75 degrees. This information does not mean you need to purchase a soil thermometer, but it does give a clue on seed sowing dates. Lettuce could be directly sown in late April/early May, while muskmelon may do better to be placed in the soil as a transplant or sown directly in late May/early June when the weather is warmer.
Moisture: The soil you have placed your seed in needs to be evenly moist-not soggy. A rung out sponge or slightly damper is an adequate comparison to the moisture level you want to maintain for your seed to germinate. Note: Check moisture levels with your finger. If soil is dry just below the surface add water. This will promote deeply rooted plants.
Light: Often with vegetable seeds, light is not as essential for initial germination. As soon as one sees movement from seeds (root, hook, leaf, etc.) the young seedling will require lots of light for successful growth. Note: Lettuce seeds require some light to germinate.
Sowing depth: Often not mentioned in seed germination is planting depth. There are more complex factors that could dictate appropriate planting depth, but as a general rule plant seeds twice the width of the seed. A radish seed will be planted shallower in the soil than a pumpkin seed and a lettuce seed will be planted shallower than a radish seed.