Unlike spring-blooming bulbs that are planted in the fall, summer bulbs need to be planted in the spring. Summer bulbs need warm weather and warm soil. Since no one can predict the weather from year to year, there's no calendar planting date. Once the soil has dried out and warmed up to about 60 F or higher, it’s time to get summer bulbs in the ground.
Planting
Most bulbs need a well-drained site, to prevent molding and rotting. Amending the soil with compost or manure will help the bulbs grow, bloom and store energy.
In general, you plant bulbs about three times as deep as their diameter.
Care and Maintenance
Although you don't want to plant in soggy soil, once your bulbs are in the ground, you should water them in well. Then make sure they get regular water, but allow the soil to dry out between watering.
Growing Season
If you’d like to get a quick start on growing your summer bulbs, you can pot them up indoors a month or two before it’s time to transplant them outdoors. Then you can either move them into an outside pot or transplant them into the garden.
Plant your bulbs / tubers / corms / rhizomes as soon as possible after receiving them. If you need to store them before planting, open the package. Store in a cool/ cold BUT NOT FREEZING location.
Bulbs need to be planted with the top pointing up. After planting, water well. Perennial Roots should be soaked in water for a few hours right before planting. They are usually planted with the crown an inch below the soil surface. Water well.
Acidanthera These bulbs are best planted 4” deep, 8” apart. Plant in a sunny location in groups of at least 3 for the best show.
Begonias For early bloom, start indoors in pots. Leave in a warm place, 70-80 degrees. Water sparingly until growth starts. Set in bright spot, protected from direct sun. Keep soil moist. After all danger of frost is past, place pot outside. For container planting, one per 12” pot.
Gladiolus Should be planted in full sun after last spring frost. Plant 6” deep, 6” apart, protected from the wind. They may need staking after they grow 12” high.
Lilies Plant in sun 4-6” deep, 6” apart after frost has passed, with the top of the bulb no more than 2” below the soil surface. Plant in groups of 3-6 for the best show.
Dahlias Leave the tubers intact, do not pull them apart. Plant in full sun, 4-6” deep, 12-24” apart. For container planting, the general rule is one tuber per 12” pot.
Callas Space rhizomes 4-6” apart, 2-4” deep in a part shade location. Keep soil moist between watering’s. For container planting, 2-3 per 10” pot will give you a nice show.
Canna Full sun is best for cannas. Plant 2-3” deep, 1-4 feet apart. Cannas are slow to sprout. They do not require much water until you see signs of growth. Then water very other day. For container planting, plant 1 per pot.
Liatris Plant Liatris corms 12-15” apart, 2-4” deep in a sunny location. Once established, they require little water. Allow the soil to dry between watering. Liatris grow well in containers, plant 1 per 6” pot, or 3 per 15” pot.
Crocosmia Plant corms 6-8” apart, 3-5” deep. Plant in clusters for the best effect in full to pert sun.