Tulips, lilies, hyacinths, agapanthus, gardeners select plants grown from bulbs because of their exotic, colorful and often fragrant-blossoms. However, bulbs for spring-blooming flowers must be planted in the fall, while, according to Cornell University, tender summer-flowering bulbs should be treated like an annual flower and planted after all danger of frost has passed in late spring. Planting a garden with both spring and summer bulbs requires planning before purchasing and careful planting methods.
Select spring bulbs that have deep planting depths. According to the University of Illinois Extension, spring bulbs are planted two to three times as deep as the bulbs are tall when measured from the bottom of the bulb.
Select summer bulbs that have shallower planting depths than the spring bulbs. The size of summer bulbs does not affect the depth of planting; check the planting instructions for the bulbs you're interested in growing. Order these bulbs so they will arrive in time for spring planting.
Prepare the garden for the bulbs a month before planting. Dig up the entire garden to a depth of 12 to 18 inches. According to the University of Illinois, the bed of a garden that is completely dug up, "is better drained and prepared and the planting will last longer."
Incorporate generous amounts of compost, well-rotted manure, mulch or peat moss into the soil that was removed from the garden. Return the mixed soil back to the garden site.
Fertilize the soil when the bulbs are planted. Mix 5 tbsp. of 10-10-10 soluble fertilizer with 2 cups of bone meal for every 10 square feet of garden area. Dig up the soil to the planting depth and mix the fertilizer/bone meal in the soil at the bottom of the bed, so the roots will rest on top the fertilized soil.
Plant the spring bulbs in the garden. Place the pointy end of the bulb up, although bulbs will generally grow even if planted upside down. Cover with a generous layer of leaves--to identify the bulbs when planting the summer bulbs--and cover with garden soil. Water well to settle the soil.
Dig up the soil to plant the summer bulbs. Use a garden trowel, digging carefully to avoid damaging the spring-blooming plants in the layer of leaves. Put the soil removed from the garden in a container, mix in bone meal or superphosphate and spread it on top of the layer of leaves.
Plant the summer bulbs in between the plants of the spring bulbs. Add soil carefully between the bulbs and the plants, until the bulbs are covered, then add the rest of the soil. Water to settle soil.