How to Plant Allium Bulbs in Zone 7

Prepare a planting bed with full sun and well-drained soil for the allium bulbs in the early fall. Since allium requires 12 to 22 weeks of cold to prepare for spring bloom, you will need to get the bulbs in the ground by late October or early November, just before the ground hardens in zone 7.

Turn over the soil in the designated planting area using a pitchfork, breaking up large chunks to a 12-inch depth. Perform a soil test afterward, using a soil pH testing kit. Allium bulbs thrive in soil with a pH between 6 and 7.

Add an amendment to the soil if necessary. Mix lime in with the broken soil if the pH test reads below 6. Add peat moss to soil that has a pH above 7. Mix in the required amendment according to the directions printed on the package label.

Measure the width of your allium bulbs. Once you have the width measurement, multiply it by 3. This is how deep you will need to dig the holes for the allium bulbs. For instance, if an allium bulb measures 2 inches wide, you will need to dig its planting hole 6 inches deep. Use the same figure to determine planting distance. In this case, each hole should be spaced 6 inches from the next.

Press one allium bulb into the soil, bud side up. Pat the soil over top to remove trapped air in the soil. Zone 7 gardeners will also want to cover the area with a 2- to 3-inch layer of mulch to protect the bulbs during the winter and to improve drainage. Bark chips, straw or a 2- to 3-inch pile of raked leaves will also work.

Water the soil around the allium deeply after planting, saturating the soil to a 1-inch depth. After the initial watering, allium only requires light waterings when the top layer of soil begins to dry out.