A crucial part of successful gardening lies in determining the proper planting depth for each kind of plant. Bulbs and annual flowers require different planting requirements than seeds or trees. Learning about proper planting depth comes from experience but also involves recognizing that planting too deeply can stunt growth and invite disease.
Each plant purchased from the nursery comes with a label describing growing requirements. This label includes information about sunlight requirements, watering needs, fertilizing, spacing and planting depth. Follow grower recommendations to encourage the success of your plants.
Planting depth means nothing unless soil quality reflects everything the plant needs in order to succeed. Commercial growers use soil-less potting mixtures to grow annuals and many perennials from seed. Soil-less mixtures contain peat moss and absorbent pellets called vermiculite. Both encourage water retention and excellent seed-to-soil contact to speed germination.
These soil-less mixtures aren't practical in the home garden, so successful planting requires adding amendments to the dirt. Peat moss, humus and compost increase soil nutrient levels in home garden soil. Fertilizers will help keep your plants healthy but a good base in the soil adds a much-needed boost for plant and flower roots.
Planting depth for trees requires a little more effort for success. A general rule of the thumb requires the top of the tree root ball to lie slightly above the soil grade after planting. However, gardeners should dig the hole considerably larger than the tree (or shrub) to add amendments and to aid in proper positioning. Soil can be added or removed to achieve the perfect planting depth.
Nurseries sell annual and perennial flowers in plastic transplant containers. Take your planting depth cue from how the grower has arranged these flowers in the portable container. Plant annuals and perennials in the ground similar to the depth in the planting container to minimize shock to the plant.
Individual flower and plant seeds have specific requirements for planting. Larger seeds can be pressed into a soil-less potting mixture or directly into the garden. Covering these seeds with a 1/4-inch layer of soil will encourage quick germination and discourage birds from swiping the seeds.
Smaller seeds such as impatiens or petunias can be placed on top of the potting mixture with the lightest layer of soil sprinkled over the seeds to create soil/seed contact. Soil serves to hold seeds in place and send needed moisture to the seed to start germination. Fine mist sprayers can be used instead of a watering can to keep the seed in place in the soil.
Tulip, daffodil and crocus bulbs dot the landscape during the spring. These hearty flowers signal the start of spring with sturdy stems and beautiful flowers that take the edge off the winter chill. A wealth of flowering spring bulbs and summer bulbs exist for use in the home landscape. Spring flowering bulbs have a general planting depth requirement of two to three times the length of the bulb. Summer bulbs have planting depth requirements specific to the flower. Consult the planting instruction label for this information.