By: Lisa Briggs | August 28th, 2019
Are you confused when it comes to fall-planted bulbs? Lots of gardeners are. What, exactly, is a bulb? How, and when should bulbs be planted? These are questions that frequently heard at the Plant Desk. Adding spring-flowering bulbs to your garden borders is simple and rewarding, especially when those new crocus shoots emerge after a long Wisconsin winter. In these days of instant gratification, planting bulbs that won’t bloom for months might seem like a lot of trouble. But it is well worth the effort as these early spring flowers are the true harbingers of warmer weather and each type has a unique beauty.
We call them all bulbs, but bulbs, rhizomes, and tubers are essentially storage organs that contain flower buds. The bulb feeds the developing flower as it grows to maturity and blooms. All it takes is water and time. Figuring out how to plant bulbs is simple as most are planted using the same rules. Assess your sun and shade situation. Most bulbs need a sunny spot, but there are types that will thrive in partial shade. Bulbs need good drainage in order to overwinter, so don’t plant them in low areas that collect water for any prolonged period of time.
Bulbs are planted in the fall because most of them need what is called a chill period in order to blossom. The length of this varies, but it’s usually 12 to 16 weeks. No matter how deep the frost line goes, spending the winter in-ground is a gentle way for bulbs to fulfill this requirement. You’ll want to plant your tulip, daffodil and hyacinth bulbs once the soil begins to cool down. In our area, planting after October 1st is best. Bulbs can be planted as long as the ground can be worked, but flowering may be compromised if you plant much past mid-November.
All bulbs should be planted with the pointed end up. If there is no obvious pointed end, don’t panic. Most are very forgiving about planting orientation. When in doubt, place the bulb on its side, and it will figure out which way is up. There is also a rule of thumb for figuring out planting depth. Dig your holes 3 to 4 times the height of the bulb. This means that large bulbs get planted deeper than small ones. You can also layer some small types above larger ones in the same hole.
And speaking of holes, try digging a few large areas instead of lots of small ones. This way, you can mass your bulbs together in clumps or drifts. Your display will have more impact for the same amount of work. To achieve a more natural look, toss your bulbs gently onto the soil and plant them where they land. Or try planting some very early bloomers in areas like woodland edges or in lawns where mowing doesn’t start immediately.
We’re often asked about fertilizing. Applying Bulb Booster when planting will enhance the size and color of your flowers and prolong the bulb’s lifespan. Mix the fertilizer into the bottom of the planting hole. For established bulbs, work it into the ground around the bulbs in early spring as they start to grow.
Now that you know how to plant bulbs, you can have fun choosing which ones to plant. All bulbs are divided into categories of bloom time: early spring, mid-spring, and late spring. If you want a succession of bloom throughout the spring, plant some from each category. If you want one big show of color, choose bulbs that are all from the same group.