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Bearded irises don't bloom? Time to divide


Blue irises
These blue irises are family heirlooms and have been blooming consistently for more than a century -- divided and replanted all along the way. (Photos: Debbie Arrington)

This easy-care perennial benefits from division, replanting




Divide and bloom; that’s the secret to bearded irises.

They’re such a persistent (and fast-growing) perennial, they need to be divided every three years or so. Otherwise, their rhizomes – their thick fleshy roots – overcrowd each other. If too crowded, they don’t bloom.

If your bearded irises have not bloomed in more than a year (but still look relatively healthy), they likely need to be divided.

Traditionally, August is the best time to divide and replant irises in Sacramento. With a slight break in the heat and smoke expected later this week, now may be a good time to tackle your iris beds.

Division and replanting are the only major work these easy-care plants need. So, a little TLC now will pay off for years to come.

Dig up the main clump; some rhizomes will look old and withered. Cut those off and discard. The other segments can be cut or broken apart. Make sure there’s at least one “fan” of leaves on each segment to be replanted. Trim the leaves to about 4 to 6 inches long. And, if you know, write on the leaves the iris variety or color. (A Sharpie works well for this.) This helps keep them sorted when you replant – and when you share irises with friends.

Preparation of the planting bed will assure beautiful blooms for several seasons to come. Even though irises are planted very shallow, dig down at least 10 to 12 inches and work the soil, breaking up any large clumps. Spade in some well-aged compost and bone meal to promote big flowers and root development.

Bronze irises
These bronze irises are eye-catching. In Sacramento, irises are
best divided and replanted in August.

Irises appreciate good drainage and full sun. If your soil is heavy clay, add some coarse sand along with the compost and bone meal. Don’t use high-nitrogen fertilizers on irises; it promotes lots of leaves but no flowers.

To replant, form two parallel trenches with a ridge down the middle. Put the rhizomes on top of the ridge with their stringy roots running down into the trenches on either side. Space each rhizome about 12 to 18 inches apart.

The plants will grow (and rhizomes increase) in the direction the fans of leaves are pointing. Arrange the rhizomes so their fans are all pointing (at least generally) the same direction; that keeps them from overcrowding too quickly. If arranged in a circle, place the fans pointing away from the center.

Once placed, gently press the rhizomes into that ridge, making sure the top of the rhizomes will be just above soil level. Then, fill in the side trenches with soil.

Water deeply – and wait. The rhizomes will start producing fresh leaves in early fall. Water the plants occasionally so they don’t dry out, but otherwise leave them alone.

And remember to share some of those freshly dug irises with friends. One large clump can produce several new plants – many more than is needed to replant the same space. Those extra rhizomes should be replanted within two weeks.

For more on irises:
www.irises.org .

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Flowers in My Back Yard Series

Aug. 11: Hardy hibiscus adds big tropical impact

Aug. 4: Dianthus a deceptively hardy flower

July 28: Naked Ladies put on summer show

July 21: Thank Luther Burbank for these long-lasting beauties (Shasta daisies)

July 14: How to keep hydrangeas happy

July 7: Grow these bright cosmos for bees and butterflies

June 30: Agapanthus adds blue fireworks to the garden

June 23: Easy-care gazanias fill those hot corners

June 16: Daylilies are perfect for water-wise gardens (and a lot more)

June 9: Grow coneflowers for pollinators -- and yourself

June 2: Sunflowers capture Sacramento's summer attitude

May 29: Are your roses going 'blind'?

May 26: Zinnias are the summer flowers every garden needs

May 19: Plant dahlias now for late-summer flower power

May 12: Know your coreopsis from your bidens

May 5: Mums the word on Mother's Day weekend

April 28: Majestic Matilija poppy is worth a look

April 21: Celebrate roses, America's favorite flower

April 14: Small flowers with outsized impact

April 7: Calendulas do double duty

April 3: Make Easter lilies last for years to come

March 31: In praise of a pollinator magnet (small-leaf salvias)

March 24: Azaleas brighten shady spots

March 17: The perfect flower for beginners? Try zonal geraniums

March 10: Keep camellias happy for years to come

March 3: Fruit tree blossoms are a fleeting joy

Feb. 27: Are your roses looking rusty?

Feb. 24: Treasure spring daffodils now and for years to come

Feb. 17: How and why to grow wildflowers

Feb. 10: Let's talk Valentine's Day roses

Feb. 3: Why grow flowers?

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Taste Summer! E-cookbook

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Find our summer recipes here!

Garden checklist for week of Aug. 9

During this break in the heat, fertilize your garden. Make sure to water before and after applying fertilizer.

*Feed citrus trees their last round of fertilizer for the year. This will give a boost to the fruit that’s now forming.

* Harvest tomatoes, beans, squash, pepper and eggplants to prompt plants to keep producing. Give your plants a deep watering twice a week, more if planted in containers. Also, give them a boost with phosphate-rich fertilizer to help fruiting.

* Watch out for caterpillars and hornworms in the vegetable garden. They can strip a plant bare in one day. Pick them off plants by hand in early morning or late afternoon.

* Mulch can be your garden’s best friend – it conserves moisture while blocking out weeds. But don't let mulch mound around stalks, stems or trunks. That can promote rot.

* Camellia leaves looking a little yellow? Feed them some chelated iron. That goes for azaleas and gardenias, too.

* Pinch off dead flowers from perennials and annuals to lengthen their summer bloom.

* Pick up after your fruit trees. Clean up debris and dropped fruit; this cuts down on insects and prevents the spread of brown rot. Then feed fruit trees with slow-release fertilizer for better production for next year.

* To prolong bloom into fall, feed begonias, fuchsias, annuals and container plants. Always water before fertilizing.

* Fertilize fall-blooming perennials, too. Chrysanthemums can be fed until the buds start to open.

* Prepare for a fall full of flowers by paying a little extra attention to your garden. Cut off spent blooms from roses, annuals and perennials, then give them a boost of fertilizer. Make sure to water plants before feeding. Roses will rebloom about six to eight weeks after deadheading.

* Indoors, start seedlings for fall vegetable planting, including bunching onion, cabbage, broccoli, cauliflower, kale, radicchio and lettuce.

* Sow seeds of perennials in pots for fall planting including yarrow, coneflower and salvia.

* In the garden, direct seed beets, carrots, leaf lettuce and turnips.

* Plant potatoes.

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Food in My Back Yard (FIMBY) Series

Lessons learned during a year of edible gardening

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Hints for choosing tomato seeds

Starting in seed starting

Why winter is the perfect time to plant fruit trees

When to plant? Consider staggering your transplants

How to squeeze more food into less space

Potatoes from the garden

Plant a fruit tree now -- for later

Win the weed war by tackling them in winter

Tips for planting bare-root trees, shrubs and vegetables

Time to give vegetable seedlings some more space

Ways to win the fight against weeds

FALL

Add asparagus to your edible garden

Soggy soil and what to do about it

Plant artichokes now; enjoy for years to come

It's late November, and your peach tree needs spraying

What to do with all those fallen leaves?

Prepare now for colder weather in the edible garden

Plant a pea patch for you and your garden

As citrus season begins, advice for backyard growers

Change is in the autumn air 

We don't talk (enough) about beets

Fava beans do double duty

Seeds or transplants for cool-season veggies?

How to prolong the fall tomato harvest 

SUMMER

Time to shut it down? 

How to get the most out of your pumpkin patch

Summer-to-fall transition time for evaluation, planning

To pick or not to pick those tomatoes?

: Put worms to work for you

Grow food while saving water

Enhance your food with edible flowers

Why won't my tomatoes turn red?

A squash plant has mosaic virus, and it's not pretty

Does this plant need water?

 Tear out that sad plant or baby it? Midsummer decisions

How to grow summer salad greens

 Weird stuff that's perfectly normal

SPRING

Help pollinators help your garden

Battling early-season tomato pests

Make your own compost

Where are the bees when you need them?

How to help tomatoes thrive on hot days

Your plants can tell you more than any calendar can

Maintain soil moisture with mulch for garden success

What's (already) wrong with my tomato plants?

Should you stock up on fertilizer? (Yes!)

Grow culinary herbs in containers

When to plant summer vegetables

Don't be fooled by these garden myths

Fertilizer tips: How to 'feed' your vegetables for healthy growth