“When dividing iris bulbs, how many should remain in the original site, which is around 2 x 2 feet? The iris’ are of the tall, bearded variety. They are a solid royal blue. I am uncertain of the exact variety, but they have to be an heirloom species as they were transplanted in 1950 from a family member’s garden that was started in the 1920s.” Question from Ann of Raleigh, North Carolina
Answer: How wonderful to have a garden German bearded iris (Iris x germanica hybrids) that is truly a family heirloom! We have peonies that were owned by my great great grandparents. Plants like these are irreplaceable and real treasures. Care must be taken when moving them.
A 2-by-2-foot iris clump can easily be divided into quarters, allowing you to leave a 1-foot clump behind and have three to share or move about your garden as you wish. Here are a few tips for dividing and transplanting German bearded iris properly.
How to Divide German Bearded Iris
Trim back any old flower stems or dead leaves. This makes the moving process easier.
Dig beneath and gently lift the bulbous roots–removing 3/4 of the clump, in your case. Because German bearded iris roots are large, rhizomatous, and half-exposed along the soil surface, dig beneath them and break away the roots of clumps at natural breaks. Damage the roots below as little as possible. Remove any rhizomes that are sunken and damaged or dead.
Fill in holes left behind with soil and compost. Fill in around your existing clump with soil and quality compost, such as Black Gold Garden Compost Blend.
Pot or plant the iris divisions. Plant the rhizomes in a sunny location. Amend the garden soil with compost or peat moss, and make sure that it drains well. Plant iris rhizomes as they naturally grow–with the tops exposed to the air and light. Planting them too deeply can be deadly.
I hope that these tips help! Happy iris moving and planting.
“When is the best time to divide Hibiscus?” Question from Melanie of Holton, Michigan
Answer: Mid-spring is the best time to divide perennial Hibiscus (Hibiscus moscheutos and hybrids, USDA Hardiness Zone 5-9), especially when you live further north. Remember that this hibiscus requires warmth to sprout from the ground, so it is one of the last perennials to emerge in late spring. First, only divide clumps that are 8 to 10 inches across. Anything smaller is too small to create a big show in the coming summer. Then, using a sharp spade, cut down the center of the clump to split it in half. Amend the soil with quality organic matter, such as Canadian Sphagnum Peat Moss or Garden Compost Blend, before planting. A Continuous Release Fertilizer formulated for flowering perennials is also recommended.
“My artichoke has grown quite large, do I have to dig the whole thing up or can I remove offsets easily and replant them.” Question from Jean of Longview, Washington
Answer: Dividing globe artichokes (Cynara cardunculus var. scolymus) is a cinch. As offsets arise and begin to leaf out, take a sharp spade and cut down between the offset and parent plant. Then dig out the offset–being sure to dig deep enough to capture the long taproot of the offset. Then plant it where you wish. When replanting, the addition of compost, such as Black Gold Garden Compost Blend, will lighten the soil and add extra enrichment. Artichokes are tough plants that are not too demanding once established, but the application of fertilizer formulated for vegetable growing can boost bud set.
“Can you propagate orchids? My orchid has another stem growing at the bottom and I am wondering if I cut it off if it will grow and how to do that?” Question from Krystal of Lincoln City, Oregon.
Answer: Orchids with pseudobulbs, like yours, can easily be divided when the plants reach a substantial size. These orchid types include lots of common household favorites, like Cattleya, Dendrobium, Epidendrum, Laelia, and Oncidium. But, based on your image, your orchid is not large enough to divide. A strong, flowering-sized division should have at least three to four pseudobulbs. (Click here to learn more about dividing orchids with pseudobulbs.)
Your happy orchid is producing strong roots that are growing beyond the pot, which is what it should do. When its roots greatly outgrow the pot (see image below), it will be time to replant your orchid into a large pot with fresh orchid bark and sphagnum moss. The best time to replant an orchid is when it is setting new growth, often in late winter. Never divide or repot an orchid when it is in full bloom! (Click here to learn more about repotting orchids like yours.) Once your orchid has at least six to eight bulbs, you can consider dividing it. I hope this helps.