I have Japanese Iris that I purchased 3 years ago,but while the plants themselves look good I have not had any blooms since the ones that were on them when I bought them.Maybe I have not planted them correctly when transplanting then into very large containers.Any suggestions?

Debbie. Since JI need winter cold to bloom I have to ask if you're keeping the containers outside over winter?

Yes and they are in huge planters. I did divide them in the spring because as I said they seem to be thriving but just not blooming.I thought division might help.But maybe I am leaving too much of the cromes exposed .Or maybe not covering them enough. This is my first experience with iris, so I need to draw from the wisdom of others to get my Iris to bloom.

Although they're outside, maybe you need to look at how much sun those huge planters are getting in the winter, Debbie. They need to get cold and stay cold.

If they are on the south side of your house, or some other protected spot, (microclimate) they might warm every sunny day. That might be keeping them too warm through the winter to really chill the plants. They also might break dormancy early, so the cold period would be too short, possibly?

If this is the case, shading, (a white or silver reflective tarp?) or moving them to the north side of the house or somewhere else shady so they'll stay cold for a long time would help. When it snows, then melts, look at where the snow stays the longest. That's your cool spot! IF you need to water them, use a watering can with some ice in the water to keep the soil really cold. A drench of 70deg. water from the indoor tap can really raise the soil temp.

That's it! I have created a micro climate between my log home And a small building next to it.It is great for my raised beds and all of my plants seem to thrive there,except for the iris.I will now find them a Shady spot on the opposite side of the house where I plant things that need mostly shade.Thank you for sharing that information to me.I can't wait to see my iris in bloom. Moving day for them is tomorrow!!!

It could be also that your plants are getting too rich nutrients and growing lots of tops, leaves, and not making blooms. ? Do you fertilize them? Some plants do like lots of fertilizer, I don't know about these, but maybe someone else will. I do think that is a good idea to put them in a north side for the winter and then move them to the sun in the spring. I see that you are a new member. We also have an iris forum, there are several threads there about Japanese iris that may hep you. Here is a link to one of the longer threads, has lots of info and pictures.

The thread "Japanese iris" in Irises forum

You know who has fabulous J. Iris is pirl, maybe she can help. @pirl

I've heard some gardeners say they have failed at growing JIs in containers, I'm unsure why, but maybe they would be happier in the ground. They are heavy feeders and like lots of moisture. Perhaps the root zones are getting too dry during the growing season, or maybe too hot?

Thanks for the alert, Julia.

Elaine seems to have the answer here - a spot that stays cold all winter, then sunshine in spring. They'd enjoy the rich soil. Have you tested the pH of it? A simple (cheap) meter from HD, or any similar store, will give you a good idea of the pH, moisture and light. JI's enjoy an acidic soil.


You did mention they might not be planted deeply enough. They should be two inches deep but you can just add manure and compost (and mulch) so there's no need to dig them and replant them. I do think they do better planted in the good earth but in Arkansas they may remain cooler in pots. The roots have to be well covered. As they age they push themselves up in the soil so check them twice a year. Just as a side note: they should never be planted where a JI has grown. Allow a few years to pass and improve the soil before you plant another JI in that spot. I know there are some people who will dispute that fact but even the large JI nurseries abide by that rule so I do as well.


Good luck with your JI. I hope you enjoy them as much as I do!

Here is Greywoods Yarragon in bloom less than two months from receipt from Greywood Farms. http://greywoodfarm.squarespac...

Neal - you raise good points. They would be hotter in a container than in the soil. Maybe they are heavy feeders but I have six gardens of JI's and do not feed them except for compost when I think of it, have time, have energy to dig into the compost bins! I will not use Miracle Gro due to the salt build-up. Any azalea or rhododendron food would be ideal for those good gardeners who do feed their plants. The JI's DO love moisture and mulch will help with evaporation.

Arlene, I'm glad to hear you don't fertilize; I only use manure as a top dressing for them (in theory, a couple of times a year, but in reality, I'm lucky to get it done once a year, LOL). The soil here is naturally fertile and loamy, so anything I add creates a pretty cushy place to grow for most plants.

Thanks to all for the excellent information.I am looking forward to putting these suggestions into action.Another question,is rabbit manure good for feeding iris?

If your pots are a dark color, that will contribute to the soil staying too warm. You could cover them with some aluminum baking foil in the winter to deflect some sun. ? I think that would help, if they are in the shade though, this wouldn't matter. I have had plants in the summer get too warm from dark colored pots.

I haven't used rabbitt manure, but I've read several places that it's excellent, and can be safely used fresh.

Neal - we make our own compost and add to it continually. The JI's love manure. I have no experience with rabbit manure but someone here at ATP loves it for her clematises. We also have great soil, and after more than 20 years and tons of compost, and manure as I can manage it, we have excellent water retention. We're about 200' from the water but do not have sandy soil, thankfully.

I'm most likely to use the azalea/rhododendron food when I buy it and then somehow it ends up on a garage shelf and I stop thinking about it.

Frilly is right about the pot color and it attracting even more heat in summer. Perhaps you could put your pot inside of a lighter colored pot.

Ladybug - I did a trade of JI's for Louisiana irises with Kathy Ann Allgood, also in Arkansas, years ago. I will attempt to contact her to see how well they're growing for her and if she has any helpful hints for you.

My regular iris stay in pots all year round. In winter I take them into the garage which stays no colder than around 45-50, then in the spring when it stops going below freezing I put the pots out. They seem to bloom okay. I also have some in the ground with iffy results. I have some JI's around my garden (now know I must move some of them as they are not in spots that get lots of sun. I guess I though they would like some shade being more delicate. I don't think mine have bloomed yet either (the JI's). Hopefully this summer some will bloom so I can tell which is which. I have Siberians also and they look a lot like the JI's when only plants. I would say not enough sun is my problem. The Siberians out in full sun go nuts. Have had to split them every other year or so.

Just because the JI's appear delicate, that doesn't mean they'd like shade. In most zones they can handle and thrive in full sun. They are darkest in color on opening day, then gradually get lighter in color until deadheading is in order. Here in zone 7 the JI's enjoy full sun from dawn to dusk. Those that do get some shade bloom well but still get 6 hours of sun.

Here's Variation in Pink and it shows the big change from a newly opened bloom, on the left, to one open for two days, on the right. On the far right you can spot an unopened bud you'd be certain would end up being purple but it's a bud from ViP.

Arlene, I'm glad you mentioned Kathy Ann's JIs. We're facebook friends and she posted pics last summer of her JIs- they were gorgeous! She has them planted out in the garden, and they're clumping up beautifully.

Her LA irises have done exceedingly well here. I'm glad the JI's are happy in Judsonia, AR!

I did write to her for any help she can offer Debbie.

Would morning sun and afternoon shade be what my IJ needs.