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Flag this! Dig and divide now for more flowers next spring


These are Debbie Arrington's heirloom blue flag irises.
(Photo: Debbie Arrington)
Did your bearded irises stop blooming? They likely need late summer rejuvenation



By dividing, these plants multiply.

Bearded irises rank among the best-flowering perennials for the Sacramento garden. They’re low maintenance, drought tolerant and reliable. They pretty much take care of themselves most of the year, dying back in fall before re-emerging for a massive spring flower show (and sometimes more in fall).

But every three to five years, bearded irises need to be dug up and started over. That’s the key to their durability and consistent bloom.

If a bearded iris in your yard has stopped blooming, it most likely needs to be divided. In the end, you get more plants – and more flowers.

Timing is everything with this chore; irises need to be divided and replanted in late August or September to get ready for winter dormancy. So now is the right time to dig up the iris bed.

Bearded irises grow from rhizomes, fat segmented tubers that grow just under the soil. Over time, the rhizomes lose their vitality. They rot or wither away. Side shoots grow from the central rhizome to form new baby rhizomes. It’s those baby rhizomes that will produce the future blooms.

Each rhizome produces thumblike protrusions with fans of leaves attached. Once a “thumb” produces a flower stalk, it won’t bloom again. So, any segments attached to flower stalks should be discarded, allowing room for the other “thumbs” to grow.

How do you know which to keep, which to cut? Dig up the rhizomes and look.

Shallow-rooted, they come up very easily, pried from the ground with a pitchfork or spade. (Be careful not to whack the rhizome you intend to keep.)

Once they're unearthed, wash off the rhizomes with water and start working them apart, using your fingers and a trowel or sharp knife. Keep the young, healthy rhizomes with one or two fans of leaves and healthy roots attached. Break off the aged, bloomed-out, rotted or dried-out pieces and discard. Also look for insect damage; cut that out, too.

Now, you’re ready to replant. First, rejuvenate the planting area with some well-aged compost and a little bone meal, worked into the top 6 inches of soil. On the irises, trim the leaves down to 4 to 6 inches.

Plant the rhizomes about 12 inches apart so the fan of leaves sits right on the soil surface, with the rhizome just under the soil. Unlike most perennials, don’t cover these with mulch. (That can promote rhizome rot.) Water deeply once, then let rest.

The irises will take over from there.

This method will keep a clump of bearded irises blooming and healthy for generations. I know. With unusually tall and fragrant flowers, this clump of old-fashioned blue flags originally came from my great-grandparents’ farm. Growing in the same spot for 70 years, it gets dug up and replanted every five years or so. And it’s still blooming strong.

A little extra effort two or three times a decade pays off.

Want to learn more about irises? Check out the Sacramento Iris Society:
https://sacramentoirissocietydotcom.wordpress.com/

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Garden Checklist for week of Jan. 12

Once the winds die down, it’s good winter gardening weather with plenty to do:

* Prune, prune, prune. Now is the time to cut back most deciduous trees and shrubs. The exceptions are spring-flowering shrubs such as lilacs.

* Now is the time to prune fruit trees. (The exceptions are apricot and cherry trees, which are susceptible to a fungus that causes dieback. Save them until summer.) Clean up leaves and debris around the trees to prevent the spread of disease.

* Prune roses, even if they’re still trying to bloom. Strip off any remaining leaves, so the bush will be able to put out new growth in early spring.

* Clean up leaves and debris around your newly pruned roses and shrubs. Put down fresh mulch or bark to keep roots cozy.

* After the wind stops, apply horticultural oil to fruit trees to control scale, mites and aphids. Oils need 24 hours of dry weather after application to be effective.

* This is also the time to spray a copper-based fungicide to peach and nectarine trees to fight leaf curl. (The safest effective fungicides available for backyard trees are copper soap -- aka copper octanoate -- or copper ammonium, a fixed copper fungicide. Apply either of these copper products with 1% horticultural oil to increase effectiveness.)

* When forced bulbs sprout, move them to a cool, bright window. Give them a quarter turn each day so the stems will grow straight.

* Browse through seed catalogs and start making plans for spring and summer.

* Divide daylilies, Shasta daisies and other perennials.

* Cut back and divide chrysanthemums.

* Plant bare-root roses, trees and shrubs.

* Transplant pansies, violas, calendulas, English daisies, snapdragons and fairy primroses.

* In the vegetable garden, plant fava beans, head lettuce, mustard, onion sets, radicchio and radishes.

* Plant bare-root asparagus and root divisions of rhubarb.

* In the bulb department, plant callas, anemones, ranunculus and gladioli for bloom from late spring into summer.

* Plant blooming azaleas, camellias and rhododendrons. If you’re shopping for these beautiful landscape plants, you can now find them in full flower at local nurseries.

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