How to Divide Spring Bulbs Before Winter for the Best Blooms Next Year

If you notice that your spring bulbs are producing fewer blooms, it could be a sign that they need to be divided. It's not a difficult garden chore, and it's one you'll likely need to do every few years to ensure your bulbs continue thriving, but there are a few nuances to know before you dig in and start dividing. Ahead, our experts explain how and when to divide your spring bulbs before winter for the best success. 

When to Divide Spring Bulbs

Spring bulbs tend to bloom early in the year, and maintain their foliage for several weeks after the blooms fade, which refuels the bulbs via photosynthesis. When this process is complete, the foliage fades for the summer and fall and reemerges the following spring. "The easiest time to divide spring bulbs is in late spring or early summer, after the leaves have absorbed enough sunlight to recharge the bulbs for growth next year," says author Jenny Rose Carey. "You can still see where the bulbs are buried and locate where to dig so that you don't cut through the bulbs."

If you didn't divide your bulbs in the spring, you're not out of luck. "All bulbs can be divided anytime that they are dormant—that is when they are in their resting phase underground," explains Carey. However, digging up your bulbs may become impossible in winter in some regions. "Depending on your region and hardiness zone, you want to dig before the ground starts to freeze, so by late-October to mid-November for most," says author Kathy Jentz.

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How to Divide Spring Bulbs

Dividing bulbs is easy, but you'll need to do some initial research before getting started. There can be variations in the steps and timing depending on the plants you are dividing. For example, Carey notes that when dividing dahlias, some gardeners may assume that every bit of root will grow. "Only the pieces that have a couple of shoots on the main tubular stem will grow," she says. "Divide very carefully and include part of that central stem."

Knowing the specific needs of your variety will help with the dividing process. That said, here are some general guidelines to follow when dividing bulbs.

1. Carefully dig up the bulbs: "The biggest mistake is stabbing the bulbs and injuring them with your garden fork, spade, or shovel," says Jentz. "If you know approximately where they are, take a step back and insert your garden fork and gently pry up the soil surrounding the bulbs—stopping and backing up again if you hit any bulbs or meet any resistance." Get your tool below the bulbs, then gently lift up.
2. Separate strategically: Remove the many small bulbs that have clustered around the original group. Garden shears or a knife may help cut sturdy rhizomes. But don't over-separate. "When dividing bulbs, I keep small groups of bulbs together," says Carey. "If you divide them and plant them as single bulbs, the resulting display can look rather spotty."
3. Be selective: Dispose of damaged bulbs or any that seem unhealthy. Give the original parent plant a light squeeze—if it yields significantly to your touch, its best years are probably behind it, and you might want to retire that one and replace it with one of the smaller new bulbs. But if it seems firm and healthy, you can replant the original.
4. Clean divided bulbs: Brush and wash the dirt away from your buried treasures, then dry them in a shaded place, unless you're replanting immediately. Make sure each division has one eye. 

How to Store Bulbs Over Winter

For tender bulbs that cannot be kept outdoors during winter, you'll need to keep them indoors during the cold months. To store tender bulbs such as cannas and dahlias after dividing them, Carey says to aim for moderate conditions. "The tender bulbs will survive best if they are not too hot or too cold, and not too wet or too dry," Carey says. "Find an area in your house or garage where you can store them and check on them every week or two." She suggests wrapping them in layers of recycled paper. "I can damp them down if they look a little shriveled or open the packages up if they look wet or become moldy," she adds.