Are you confused when it comes to fall-planted bulbs? Lots of gardeners are. What are bulbs, and how, and when should they be planted are questions that we often hear at the Plant Desk in late summer and early autumn. Adding bulbs to your 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 blooming flowers are the true harbingers of warmer weather and each type has its own unique beauty.
We call them all bulbs, but bulbs, rhizomes, corms and tubers are essentially storage organs that contain flower buds. The structure 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 some, like daffodils and fritillaria, that will do well 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 many of them require 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, wait until late September or early October. 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 determining 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 area for a delightful mix of flower forms and colors.
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 a good slow-release bulb booster will enhance the size and color of your flowers and prolong the bulb’s lifespan. At planting time, 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. We especially like the organic Bulb-Tone by Espoma.
Now that you know how to plant bulbs, you can have fun choosing which ones to plant. All bulbs can be divided into categories of bloom time: early spring, mid spring, and late spring. This is usually noted on the packaging. 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.