What Is the Appropriate Depth for a Container Used for Starting Flower & Vegetable Seeds?

General Seed Starting Tips

• Always use flower and vegetable seeds before their expiration dates. The expiration date of the seeds will be listed on the seed packaging. Virginia Cooperative Extension recommends storing seed packages in an airtight plastic container in a dry, cool storage place featuring low humidity and temperatures of about 40 degrees Fahrenheit until you are ready to plant. Choose seeds that will grow into plants that will thrive in your planting zone. Light exposure is essential for starting seeds. Seeds should be exposed to light for about 16 hours a day. In addition to providing natural sunlight, position fluorescent lighting about 12 inches above the seed containers. Virginia Cooperative Extension recommends keeping the environmental temperature around the seeds between 65 and 75 degrees Fahrenheit for optimal growth.

Container Depth for Seeds

• Regardless of the container selected for starting your flower or vegetable seeds, it should be filled until the soil level is 3/4-inch below the top rim or lip of the container's sides. Small seeds, such as carrot seeds, require a 1/4-inch top layer of a very fine soil mixture. Plant medium to large seeds in straight rows spaced about 1 to 2 inches apart. Press the seeds about 1/4-inch deep into the soil. Garden stores offer some planting systems that feature individual containers filled with a premixed soil pellet that is rehydrated at the time of planting. These systems eliminate the need to create rows. Purdue University Cooperative Extension Service suggests moistening the soil mixture used prior to pressing the seeds into it.

Soil Mixtures

• Garden stores offer many prepared soil mixtures that contain a balanced amount of nutrients necessary for starting flower and vegetable seeds. Soil comes in bags or as pellets to be rehydrated with water. Soil used in planting containers should not be firmly packed into the container, but loose so air can circulate. Prepared soil mixtures are preferred over soil scooped from outdoors because purchased soil mixtures are free of other seeds, such as weeds, and mature insects or insect eggs. Virginia Cooperative Extension reports that most soil mixtures used for starting seeds consists of vermiculite and sphagnum peat moss.

Types of Containers for Growing Seeds

• Almost any type of container can be used for starting flower or vegetable seeds, including plastic or clay pots, biodegradable trays or containers formed of pressed papers or peat intended to be transplanted into the garden along with the seedling, or recycled containers such as margarine tubs or halved milk cartons. Purdue University Cooperative Extension Service stresses that whatever the container choice, it should have good drainage. Poke small holes with a skewer or nail into the bottoms of containers that don't naturally breathe, such as plastic.