The easiest way to start cucumber seeds is with peat pots. These natural molded pots are biodegradable and made with peat (partially decayed vegetation). It's convenient, because you don't have to remove the cucumber seedling from the pot when you plant it outdoors. These types of pots are easy to find at local nurseries or garden centers.
Fill peat pots with a commercial potting soil, to 1/4 inch from the top. This type of soil is perfect for seeding, as it is weed seed and disease free. Cucumber seeds should be started indoors 3 to 4 weeks before the last frost in your location.
Make a small hole, about ½ to 1 inch deep, with a pencil or your finger in each peat pot. Drop 2 or 3 cucumber seeds in the hole and gently push soil over the top.
Place 12 to 14 peat pots in a metal or plastic tray. Add a quart of water to the bottom of the tray. The peat pots will soak up the water, moistening the soil. Mist the top of the soil with a water bottle mister. The soil should be moist, but not sopping.
Place the tray in a sunny window. Check the soil each day. If it starts to become dry, mist the top of the soil. If the pots are light when you pick them up, add water to the tray bottom. Cucumbers grow shallow roots, making it important to keep the dirt moist at all stages of growth.
Thin the cucumber seedlings to one strong plant in each peat pot. Choose the one that is tallest and well formed, discarding weaker, smaller seedlings. This should be done before transplanting them to your vegetable garden.
Transplant your cucumber seedlings when the last frost has passed. Cut an X on the bottom of the pot and slice down each side. This will make it easy for young cucumber roots to grow outwards.
Make a garden row, about 8 to 12 inches wide. Use your hoe to make a moat on each side of the row. Your cucumber seedlings should be spaced 1 to 2 feet apart. Dig a hole slightly larger than the peat pot for each seedling. Place the pot in the hole and surround it with soil. The soil should reach just over the top of the peat pot. Pat the dirt down to secure the plant.