Irises forum: How do you grow the best irises?

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Name: Annette
Duluth, Ga (Zone 7a)
Charter ATP Member Birds Tropicals Hummingbirder Bulbs Region: Georgia
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Cem9165
Feb 11, 2012 6:25 AM CST
I would love some advice about how to grow the best irises. Shrug!

What do you use for fertilizer and pest control?

How often should irises be watered?

What's the best way to modify the soil before planting irises?

When is the best time of year to plant irises?

Thanks ahead for your responses. Annette
"Aspire to inspire before you expire"

author unknown
Name: Betty
Bakersfield, CA
Charter ATP Member I was one of the first 300 contributors to the plant database! Birds The WITWIT Badge Region: United States of America Roses
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Betja
Feb 11, 2012 10:24 AM CST
Cem, I made a big mistake when I first got into irises by over-watering and over-fertilizing after I received them in the summer (it's in the 100's here), and I almost lost about 75 of the new ones! I had potted them up and we were preparing to leave town for a week, so we put them in an area where the sprinklers would hit them for 15 minutes each day. But too much nitrogen and lots of water in warm weather promote BACTERIAL SOFT ROT, which can kill a rhizome pretty quickly.

Oh yes, and I should mention that I am talking about bearded irises only. I don't have any of the other types and I'm sure their care is probably quite different.

Bearded Irises need only a low-nitrogen fertilizer, and I only fertilize them with a granular fertilizer twice a year. However, when I plant my rhizomes in the ground I put a handful of bone meal in the hole and mix it in. Then I fertilize in the fall (Sept-Oct) and again in very early spring (Feb. here) I get my fertilizer at WalMart for about $3.50 per box, and it's a very low nitrogen fertilizer, 6-10-10. Nitrogen is the first number of the three there. Then I sprinkle the fertilizer around the rhizome, making sure that I don't let any of the fertilizer actually touch the rhizome, scratch it in, and then water. And last year I also added a foliar feeding of MiracleGro, the kind you attach to your hose, to give them a boost. But that was a little later in the spring, when the foliage was getting lush and green (about mid-March here).

Bearded irises are somewhat sensitive to water, too, especially as the weather warms up. I water only in the early morning or late in the afternoon, when they are no longer in direct sunlight, because it gets so hot here. But in the early spring when they really start growing, as long as it doesn't get too hot I water them a lot more at any time. Bearded irises go dormant in the summer months, so just maintenance watering is fine then. But if you want the foliage to stay green all summer they need about 1/2" of water each week.

And then, of course, there are the rebloomers. They require fertilizer applications right after each bloom cycle and regular watering year-round, or as long as they will keep reblooming. Because it gets so hot here I have picked irises that rebloom over the fall and winter months rather than during the summer. So I don't start fertilizing and regularly watering them again until about September.

I hope I haven't confused you, and perhaps someone else can explain it better. I'm sure you'll settle into a routine that works best for you, and if you're in an area that regularly gets rainfall you won't need to worry about the watering like I do. Good luck with them, and I know that when you see them blooming you'll know it was well worth it.

Betty
Name: Lucy
Hamilton, MA (Zone 6b)
irises
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irisarian
Feb 11, 2012 11:49 AM CST
Betty is right, always use low nitrogen fertilizer. We use 5-10- 10. I would thing being in GA you would want Betty's instruction more than from our climate.
Name: Annette
Duluth, Ga (Zone 7a)
Charter ATP Member Birds Tropicals Hummingbirder Bulbs Region: Georgia
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Cem9165
Feb 11, 2012 6:02 PM CST
Thanks for the great information. I really appreciate it. It's wonderful to know how others grow their irises around the country. Annette
"Aspire to inspire before you expire"

author unknown
Name: Betty
Bakersfield, CA
Charter ATP Member I was one of the first 300 contributors to the plant database! Birds The WITWIT Badge Region: United States of America Roses
Irises Cat Lover Daylilies Region: California Garden Ideas: Level 1
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Betja
Feb 11, 2012 7:58 PM CST
Another valuable lesson I learned along the way is that Roundup and iris DO NOT go well together. If an iris catches some Roundup spray drift there's a good chance that the flowers will be deformed. But you can use the pre-emergent Preen right up to the plants without damage.

Betty
Name: Annette
Duluth, Ga (Zone 7a)
Charter ATP Member Birds Tropicals Hummingbirder Bulbs Region: Georgia
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Cem9165
Feb 11, 2012 8:34 PM CST
Thanks Betty. I don't use Roundup in the garden beds, I tend to weed by hand. I'm loving all of this useful information. Annette
"Aspire to inspire before you expire"

author unknown
Name: Donna
NC
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dmac
Feb 26, 2012 8:43 AM CST
I didn't know this about rebloomers but to encourage them to try reblooming you should remove the 1st flower stalk after it blooms out.

When you plant TB's they should look like a 2/3'ds to 3/4's submerged submarines in the soil. We have cool wet springs here so I try to get the iris clear of any garden debris that is prone to holding water and potentially causing rot.
Name: tabby
denver, colorado zone 5
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tabby
Feb 26, 2012 9:25 AM CST
Does anybody have any experience with using Grass Begone (or equivalent) on their iris?
Name: Annette
Duluth, Ga (Zone 7a)
Charter ATP Member Birds Tropicals Hummingbirder Bulbs Region: Georgia
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Cem9165
Mar 3, 2012 8:33 PM CST
Thanks for that great information Donna, that's exactly what I do, when planting, I leave the rhizome partially visible, and I remove all the leaf debris peridically during fall and winter, and definitely in the spring. It's now time to fertilize here, the irises are showing growth with the warm temps and rain that we've been having.
"Aspire to inspire before you expire"

author unknown
Name: Brad
iowa (Zone 5a)
I was one of the first 300 contributors to the plant database! Celebrating Gardening: 2015
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ARUBA1334
Mar 3, 2012 8:56 PM CST
I use Snapshot it is a pre emergent like Preen but a lot stronger works really really good I have very few weeds in Beds
Name: Tom
Southern Wisconsin (Zone 5b)
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tveguy3
Mar 4, 2012 5:31 AM CST
I didn't see anyone mention the need to treat for the Iris borer. In Wisconsin, we do this in April, or after it quits being below freezing at night for a period of time. I sprinkle the lawn grub treatment around, but NOT ON the rhizomes. I think the company that makes the stuff I use is Bayers, don't remeber off hand, but it's the same thing you can put on your lawn for grubs. (Maybe they aren't an issue down South?)
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Name: Betty
Bakersfield, CA
Charter ATP Member I was one of the first 300 contributors to the plant database! Birds The WITWIT Badge Region: United States of America Roses
Irises Cat Lover Daylilies Region: California Garden Ideas: Level 1
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Betja
Mar 4, 2012 10:41 AM CST
Well, at least that's one problem we don't have out here. I've never seen an iris borer, and I sure hope I never do.

Betty
Name: Lucy
Hamilton, MA (Zone 6b)
irises
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irisarian
Mar 4, 2012 10:57 AM CST
ugly little creatures.
Name: Dot or Dorothy Parker
Fort Worth TX (Zone 8a)
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Ladylovingdove
Mar 4, 2012 11:00 AM CST
Do NOT overwater newly planted irises. Just lightly water every couple of days if necessary. When I first started growing irises I watered every day in the heat, BIG mistake. I lost about half of them to rot. I pot my irises up into one gallon pots when I get them and put them in the shade. When it cools in the fall, they can then be planted with no problems. They root fast and deeply in the pots. Once potted in the pots, rooted and aclimated to the sun you can plant anytime. Most irises are delivered in the middle of the hot summer. Here in Texas, this works best for me.

Dot
Name: Betty
Bakersfield, CA
Charter ATP Member I was one of the first 300 contributors to the plant database! Birds The WITWIT Badge Region: United States of America Roses
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Betja
Mar 4, 2012 12:55 PM CST
That's what works best for me, too, Dot -- too hot to subject them to our soil and sunlight in the summer, and they are beautifully rooted by Sept.!

Betty
Name: Jo Ann Gentle
Pittsford NY (Zone 6a)
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ge1836
Mar 4, 2012 3:00 PM CST
I planted iris first time a couple of years ago.I wondered why I had to keep removeing soil from the rizomes in spring,they would be burried.
I believe I dug the hole too deep in the first place and the rizome settled down when the plant sank.
I have to give a big hand to anyone who has su ccess and lots of plants.
They are not the easiest plant in the garden.
Name: Lucy
Hamilton, MA (Zone 6b)
irises
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irisarian
Mar 4, 2012 4:27 PM CST
arilbred irises really like to dig their own holes.
Name: Polly Kinsman
Hannibal, NY (Zone 6a)

Charter ATP Member Region: United States of America I helped plan and beta test the plant database. I was one of the first 300 contributors to the plant database! Irises Lilies
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PollyK
Mar 4, 2012 6:08 PM CST
I think it's a great idea to pot them and put them in the shade in the hotter zones.

Just one comment I wanted to make on watering. I have very sandy soil and I water my bearded right along with my beardless. On very sandy soil they can take watering daily, which I often do during the summer. I have never had rot. On heavier soils I would not do that.
Name: Betty
Bakersfield, CA
Charter ATP Member I was one of the first 300 contributors to the plant database! Birds The WITWIT Badge Region: United States of America Roses
Irises Cat Lover Daylilies Region: California Garden Ideas: Level 1
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Betja
Mar 4, 2012 7:17 PM CST
I have very silty soil that does not hold moisture, and I even go so far as to put mulch around my irises in my hottest bed in the summer. There is this one particular brand that I purchase from a local nursery and I try to make sure it stays about 1"-2" away from the actual rhizomes, but by the end of summer with my hand watering the mulch has pretty much spread all over the place and everything is still fine. This is the only way I've been able to keep the foliage in that bed from burning.

Betty
Name: Polly Kinsman
Hannibal, NY (Zone 6a)

Charter ATP Member Region: United States of America I helped plan and beta test the plant database. I was one of the first 300 contributors to the plant database! Irises Lilies
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PollyK
Mar 4, 2012 7:50 PM CST
Mine is all mulched with straw. Very easy and light.

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