The battle of dividing bulbs and perennials

naHave you noticed your Iris or Day Lilies looking a little pale or beginning to outgrow their space? Are any of your other bulbs, or for that matter perennials like calendulas dying out in the center? If so, fall is the right time to divide and replant these or other spring and summer blooming plants that grow back year after year.

Dividing established bulbs and perennials during autumn months is the easiest and quickest way to make them healthier - while gaining new plants for your garden or for sharing with your neighbors. The best candidates for division are perennial plants that have large, healthy clumps and have been in the ground several years. Here are the rules for dividing each category.


Certain bulbs need dividing or separating in order to maintain a healthy, flowering stand. Crowded bulbs are less likely to produce a high quantity and quality flowers. When flower number and size starts to diminish, consider separating the bulbs and replant. Bulbs planted at recommended depths initially require less dividing and resetting.

Spring flowering bulbs such as daffodils, tulips and hyacinths should be divided in September or October. Granted, it is difficult to determine the location of the bulbs without staking or mapping them out previously. Care should be taken when digging to prevent damage to bulbs. It usually is easier to dig a large area and separate bulbs then trying to dig individual bulbs separately.

If bulbs are planted among trees, shrubs or perennials consider replacing the bulbs every three to five years instead of separating. This minimizes damage to the root system of the nearby plants. Summer flowering bulbs can be divided in early April or late fall. Some bulbs, including Surprise Lilies (Lycoris) may not appear to need dividing. However, plants will produce more flowers if divided. When dividing or separating bulbs, carefully remove side bulbs from the main bulb. Replant at correct spacings.

The following table provides a guideline for dividing bulbs. Bulb Years to Divide Tulips 3 - 5 Daffodils 3 - 6 Hyacinths 2 - 3 Lilies 4 - 6 Surprise Lily (Lycoris) 3 - 5 Iris (Bulbous types) 3 - 6 Alliums 4 - 8 Crocus seldom needed Grape Hyacinths (Muscari) seldom needed.


  • 1. Try to divide dormant perennials on a cloudy day when the weather is dry, making sure each plant division has more roots than shoots.
  • 2. Use a shovel to dig deep all the way around the plant and gently lift out of ground with your hands.
  • 3. Keep as much of the root system intact as possible. If working with a very large clump, force the shovel under the root ball to loosen before you lift plant.
  • 4. Shake off loose soil and wash the crown with a garden hose until you can clearly see roots and crowns.
  • 5. Each division should have two to five strong shoots with ample roots attached. Divide the plant into smaller clumps either by hand, or with a knife or spade. Roots of some older clumps can be so tough that you'll need to chop them with a hatchet.
  • 6. Remove any dead areas and cut back remaining foliage to half the height of the original clump. Tall plants like Iris should be cut so the outer leaves are slightly shorter than the center leaves.
  • 7. Replant divided perennials promptly so roots don't dry out. Set plants out at the same depth as before, making sure to replant one division back into the original hole.
  • 8. Dig the hole slightly larger than the division to allow space for the new plant to spread out its roots.
  • 9. To finish up, water thoroughly and apply mulch to keep soil from drying out and to protect the plant's root system.
  • 10. Keep the soil moist until your new plant becomes established. Wait until spring before adding fertilizer.

Randy Lemmon is the host of the GardenLine radio program on Newsradio 740 KTRH. Randy has been doing GardenLine in one capacity or another since December of 1995, for all three of the now Clear Channel AM stations - KTRH, KPRC & KBME. When Randy took over GardenLine, he replaced long-time Houston radio veteran and GardenLine originator, Bill Zak. For those who remember that far back, GardenLine was a weekly radio staple on KTRH from 10 a.m. to Noon Mondays through Fridays - along with a Saturday show as well. Now GardenLine is heard exclusively on Newsradio 740 KTRH on weekend mornings.