Growing your own vegetables doesn't have to mean spending a lot of time and energy digging up a chunk of the yard. A container as compact as a window box can support some small but tasty veggies, making it a great option if you have limited space or sun—or if you don't have the resources to care for a larger garden. A window box planting is also an easy way to introduce kids to the fun of growing and harvesting their own food.
Some potting soils are hard to wet. Try watering a handful of potting soil first; if the water pills on top of it and fails to penetrate, you'll want to pre-soak your potting soil. Fill a bucket or tub about halfway with potting soil. Add some water and knead it into the soil with your hands; repeat as needed until the soil is evenly moist but not so wet that it drips water when you squeeze it. (If the mixture does get too wet, simply add more dry potting soil until the moisture level is right.)
Dump the potting soil into the window box and gently spread it out evenly with your hands. Tap the window box on a hard surface a few times to settle the potting soil a bit. Add or remove soil so the final level is about 1/4-inch below the rim of the window box.
Decide how many rows of each veggie you want to plant. With your fingers, make a shallow trench about 1/4 inch deep for each row, following the spacing recommendations on the seed packets.
About 1 inch in from the side of the window box, sow two rows of the radish seeds about 1/2 inch apart. Sow the carrot seeds about 1/2 inch apart in short rows next to the radishes. Sow the lettuce seeds about 1 inch apart. If you'd like, write the names of the veggies on small markers and insert at the ends of each row.
Cover the carrot and radish seeds with about 1/4 inch of soil. Pat the soil to firm it over the seeds, then water gently.
Set the planted window box in a warm, sunny spot and keep the potting soil evenly moist to encourage the seeds to sprout (usually 3 to 5 days for the radishes and a week or two for the carrots).
When the radish seedlings reach about 2 inches tall, thin them to 1 to 2 inches apart. Thin the carrot seedlings to about 2 inches apart when they reach the same size. In each case, use scissors to snip off the excess seedlings right at the soil level instead of pulling them out so you don't disturb the remaining seedlings.
Continue to water regularly, keeping the potting soil evenly moist but not soggy. If the potting soil you used does not include fertilizer, give your veggies a nutrient boost with a dose or two of a liquid organic fertilizer; apply it according to the directions on the label.
Begin harvesting the radishes and then the carrots when their roots swell to at least 1 inch across.