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    Save the Date: Perennial Plant Society’s 30th Plant Sale is April 4, 2020, 9 a.m. – 1 p.m. at the new Expo 3 Building at The Fairgrounds Nashville. Here’s where you can find the newest varieties of perennials, shrubs, vines and annuals from local growers, along with long-time, never-fail favorites, ready for spring planting. Learn more at the PPS website.

     

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When will Siberian irises bloom?

Question: I received several clumps of Siberian irises from a friend last spring. I didn’t plant them right away, but when I finally did plant, I watered them well and added some fertilizer. They looked a bit limp for awhile and finally recovered, but they didn’t bloom. Should I expect blooms this year?

siberian irisIrises are among the season’s loveliest flowers. The big, beautiful bearded irises that are putting on such a show right now seem to be unconcerned about when and how often they’re moved and usually bloom without fussing. But according to the American Iris Society, Siberian irises don’t like to be disturbed once they’re established, so they may sulk for awhile when they’re moved. If the roots dried while they were waiting to be planted, that may have dealt them another blow. AIS cautions that the roots should never be allowed to dry out while they are out of the ground, and they should be watered heavily after they are transplanted.

Last year, the newly planted irises may have spent the spring and summer getting a strong root system established. By this year, you may have a few blooms.

In general, here is what Siberian irises need to do well: slightly acidic soil in a sunny location (though AIS says they can tolerate light shade), and regular moisture. While the rhizomes of bearded irises should be planted almost on top of the soil, Siberian and other beardless varieties should be set slightly deeper in the ground. All beardless irises should be fertilized regularly.

Too hot to bloom!

QUESTION: I have a pot of impatiens that was doing well, but now the flower buds have been dropping off or turning brown before opening. The pot is always in the shade and I keep it well watered and fed. It has nice green leaves, just no flowers. Any idea what could cause this?

If there are no other symptoms – no spotting of the leaves, no rotting of the stems, no powdery coating or other unusual growth – a good guess at the source of the problem would be the long period of extreme heat. Even in the shade it has been extremely hot (remember that day it hit 109 degrees?) and plants in containers may suffer more because the pot can dry out quickly. A plant under stress will shed its flowers first.

By now, with several days of rain and more reasonable temperatures, the impatiens (and many other things) should begin to recover.

This is a good time to mention again, though, an email I received from UT Extension plant disease expert Alan Windham, in which he warned about the development of downy mildew in beds of impatiens. Watch for plants that are losing leaves, that don’t flower, and that have white growth on the undersides of the leaves, he advises. This disease can be extremely damaging, so pull up, bag and dispose of infected plants to keep it from spreading. There’s more about it at UT Extension’s Soil, Pest and Plant Center Facebook page.

…And too hot to plant, too

QUESTION: My daughter has thinned out her iris bed and given some to me.  She has given me the whole plant (bulbs and stems). I know I can not plant them at this time but how do I store them until they can be planted in November or December?  Do I need to cut the stems off now or leave them as is?  Thanks for any information you can provide. 

You’re right, with too much heat and still too little rain, it’s a bad time to plant anything. Irises are pretty hardy so you can wait to plant the rhizomes.

For now, cut the leaves off to about 3 to 6 inches, and remove as much of the soil from the rhizome as you can. Don’t wash them, just brush off the dried soil. Check to make sure there are no rotting places, insects or diseased-looking spots (discard those if there are) and store them in a cool, dry place.

You don’t need to wait until November to plant them. While they’re pretty hardy, they’d still rather be in the ground, so consider planting in September, or after the worst of the summer heat passes.

When you do get ready to plant, here’s a helpful link from the American Iris Society that provides information.

Another reminder about watering: In spite of all the rain lately, we’re still experiencing severe drought conditions in Middle Tennessee. Young trees suffer most. If you planted trees this spring, give them a little extra attention to help them make it through this hot, dry summer. Click here to see the Nashville Tree Foundation’s guidelines and tips to help keep your trees healthy.

Iris time in Tennessee

QUESTION: When is the right time to divide irises?

Bearded irises can be divided after they finish blooming.

Bearded irises, the large, showy flowers that have fuzzy patches on the outer petals, are putting on a pretty nice show across the region right now, and they’ll continue to bloom for several weeks.

After they have finished blooming, the rhizomes can be thinned out and divided if needed. But if you don’t get to it right away, you can wait until later. Irises are resilient and can survive being moved as long as they are re-planted properly.

Garden expert Judy Lowe recommends this method in her book, Month by Month Gardening in Tennessee & Kentucky:

Cut the leaves into a 6-inch high fan shape, then lift the clump with a spading fork and gently wash the dirt from the tubers. Cut off any soft, mushy or damaged parts, then cut the rhizome into smaller pieces, each with an eye or bud, using a sharp knife.

Lowe recommends dipping each rhizome into a fungicide solution to reduce the chance of fungal problems; one part liquid bleach to nine parts water is one suggestion to use.

Replant the rhizome sections close to the soil surface and water them well. Rhizomes of bearded irises should be planted so that their tops are visible above the soil. Iris beds should not be mulched.

In general, you may need to think iris beds every three to five years.

News & Events

Nashville garden specialist Barbara Wise has a passion for pots – that is, planting and growing container gardens. She now has a new book out: Container Gardening For All Seasons.

“I wrote it for new gardeners and for those who like simple (easy) steps to follow that will help them succeed as gardeners,” she says.

The book features 101 container “recipes” that any novice gardener can follow – she tells what plants to buy, what size container to use, how to place the plants, and substitutions to consider if you can’t find (or don’t like) the suggested “ingredients.” But it’s also nice for experienced gardeners who are looking for new ideas. It’s published by Cool Springs Press; retails for $19.99 and you can order it through Parnassus Books and Amazon.