Spacing for Irises ???

I'm confused. In the PF for Irises (for each variety) the spacing is listed at.....

Spacing:
12-15 in. (30-38 cm)
15-18 in. (38-45 cm)

I thought the spacing was 24", at least that is what I just planted mine apart (I even used a metal measuring tape to make sure it wasn't less than 24", lol).

Can you Iris experts explain and help, please?

Thanks!

Marilyn

Some of that depends on what sort of immediate effect you want in your garden and how often you want to divide your irises. Some of it also depends on the types of irises you're planting.

If you don't mind dividing every couple of years, you can plant most irises at 12-18" spacings. However since irises bloom best on clumps that have been undisturbed for 2-3 yrs, you may never see really spectacular bloom on mature clumps dividing that frequently. And if you plant that closely and don't keep your clumps divided frequently, you run the risk of overcrowding your plants, having clumps running into each other and perhaps choking each other out, and spreading diseases from one clump to another much more easily.

I plant my MDBs and SDBs at 12" spacings, and the taller medians and talls at 18-24" spacings depending on the bed I'm working on. I plant beardless irises at 24" spacings.

Laurie

You kind of have to make your own decision on spacing, depending on all the factors Laurie mentioned, and also your climate. If you live where it's wet and rainy, you would definitely want to plant them farther apart than if you live where it's dry and arid.

In PlantFiles, the taller iris are listed as 12-15 and 15-18 because that's what our resources recommend as a general rule, but you do still have to weigh in the other factors to determine what spacing would be best for your garden conditions and how often you want to divide them.

Marilyn,

I see you are adding iris cultivars to PlantFiles. Thank you! We really appreciate all the help.

Two things that I noticed are for the introduction date, we use the date it was registered with AIS. I know that if you don't have a subscription to AIS you can't get that information, but I just wanted to let you know that we have corrected some of your entries, in case you noticed that. If you don't have AIS, that's fine, we can correct the year.

Also, we don't use the first name of the hybridizer. We normally only use the last name unless there's more than one hybridizer with the same last name, then we use the first initial.

Not serious things, but I wanted to point it out in case you are wondering why they have been changed.

Have fun!

Joan

Joan, I'm curious. What "resources" are recommending 12-15" planting for taller irises?

LOL! Make that TWO things I'm curious about ...

Why does the PlantFiles use the registration date instead of the date of introduction, when the blank on the addition form clearly requests the year of introduction and NOT the year of registration?

Laurie and Joan,

Thanks for all your help and information! Yes, I don't plan or want to divide them very often, so I guess I'll keep it at 24". I've been planting TB's and probably will continue to buy and plant the TB's.

Marilyn

Joan,

Laurie took the words right out of my mouth! lol

I plan on joining AIS later this year for 2008, but I guess I'll just leave the date and hybridizer blank, but thanks for doing the correcting!

Marilyn

Again, spacing needs to be determined by your growing conditions and other factors as you suggested. Spacing isn't something that's set in stone, but a guideline, and just like you and I disagree on the spacing for iris, you can look at hundreds of different resources and sites and come up with differences of opinions there also. The best thing to do is take a guideline and determine what is best for your growing conditions, amount of space you have to plant, and how often you wish to divide them. For the spacing in PlantFiles, we looked at a number of sites and books and went with the majority. That was a long time ago, and I can't remember which ones they were right now. If I get a chance I'll do a search again and see what I come up with.

We use the registration date for iris, hosta, daylilies and a few others that have a register. In those instances, it keeps the entries more uniform, and we aren't really interested in which site sold it which year. If you will notice some iris retail sites, they have some labeled as new introductions, when in fact they are a few years old already. Sometimes they use the year as the year it was new to their site, not when it was actually a new introduction. We realize that it says introduction, rather than registration, but then there's a few things in PlantFiles that were set up originally to be uniform straight across the board, for all plants. Each genera doesn't normally have it's own set of fields. In some instances they do, but not usually.