How to Plant Bulbs in Montana
Montana (MT) consists of USDA hardiness zones 3 to 5. Fortunately, many bulbous plants can be planted in those zones. Bulbs hardy in zones 3 to 5 should be planted in the fall before the first frost and bulbs tender in those zones should be planted in the spring, after the last frost of the year. While every bulb is different and should be planted in a way specific for its kind, most bulbous plants can be planted in the same general manner.
Choose a location in full sun or partial shade. Most bulbous plants need at least four to six hours of sunlight to thrive.
Amend the soil so that it is well draining by tilling the top 12 inches of your soil and mixing in 3 or 4 inches of compost or peat moss. This is especially important in Montana since soil that retains too much water may freeze and thaw more often than other areas, even in the spring and fall. This extreme fluctuation in soil temperatures can harm your bulbs causing them not to bloom.
Dig holes that are two to three times as deep as the bulbs are in width. Spacing depends on what kind of bulbs they are. Lilies need about 10 to 12 inches of space to grow while snowdrops only need 3 inches of space. If you are planting bulbs that are truly corms, rhizomes or tubers, they are planted differently than true bulbs so be sure to plant them according to their individual needs.
Place the bulbs in the soil with the tips facing up. Lightly pack down the soil and water the planting site with 1 to 2 inches of water.
Lay mulch over the area. If you are planting hardy bulbs in the fall, spread about 4 to 6 inches of mulch (e.g., straw, bark, pine needles), especially in zones 3 and 4. This will give the bulbs more time to become established before the ground freezes. If you are planting tender bulbs in the spring, a couple inches of mulch will help prevent the soil from thawing and refreezing.