I'm copying this over from another thread, so we can all put our lessons in one place, where they can hopefully be easy to find and helpful.

Lessons learned from the iris garden this season

1. Single rhizomes of irises can bloom when grown in a one gallon pot, even if that pot is then held inside a ceramic pot (which could make it hotter). Fertilizer and adequate water (with saucers under the pots) is required.


A row of irises, grown in standard one gallon plastic nursery pots, inside of matched ceramic pots, on the stairs; all but the topmost potted iris bloomed (and that one may have had too many rhizomes and was too crowded)

2. One gallon potted irises can be blown over, even if they are placed inside a ceramic pot. Location, the weight of the ceramic pot, and the size of the fans and the height of the stalk, are all factors. (No two gallon potted irises have yet blown over, with or without ceramic pots.)

3. While clothing the plastic potted irises with ceramic pots make them look more presentable, this double potting also makes a hiding place for slugs and snails.

4. It is possible to add an annual plant into the 2 gallon pots, to make things look more interesting. The small annual spring (or fall) flowering white daisy, Chrysanthemum paludosum , is good for this purpose. It also has a secondary use as a snail warning system, as the slugs and snails like it too.



5. Some TB irises are so tall that the bloom stalks need support. (I already knew that with 'Sweet Musette', but I blamed it on the shady locations it was in. But the new irises are in sunnier spots, and some of their stalks flopped and broke at the base.)

6. A good solution (for those with scarce sunny space) for BB, IB and SDB irises is planting them in one gallon pots. When they are in bloom, you can put one of those pots into a ceramic pot on a patio table, and it will look nice. (When it is out of bloom, you can stash the pot in some out-of-the-way but sunny-enough spot to grow until it is time to divide; divide and repot and then grow until the next time it blooms.)

7. Shallow plastic window boxes, on the other hand, are not a good growing solution for the SDB irises (let alone the bigger ones). (Leave the boxes to grow annuals, or else to grow seedlings until they are big enough to pot up or transplant out elsewhere.)

8. If you are going to co-plant irises in near proximity, try to plant one that has Purple Based Foliage and one that does not. It will be easier to separate them out when it is time to divide.

9. 'That's All Folks' is an attention hog. It will vie for your attention against most other irises anywhere near it. The only ones that seem able to hold their own (in holding your attention, at least for a while), are tall, large flowered, blinding white ones like 'Mesmerizer'.



See also the image under Point 1; shown are the icy blue 'Glacier Point', 'That's All Folks', and the pinkish 'Peggy Sue' (behind the maple); 'That's All Folks' dominates both of them (and others not shown)

10. Check all your incoming irises as to PBF, or not, when you receive them. Make sure the foliage (PBF, or not) matches the description. This may help earlier sort out the NOIDs, so you can complain to (er, inquire of) the nursery early. (My 'Pinkity' may not be. I did a poll of everyone else here who has it. Of those that responded (including myself), three of us have plants that have PBF, and two do not. The hybridizer description and the AIS description do not mention PBF foliage. )

Lessons on perennial companion plants, from 2016 and 2017

1. Use Stachys with caution and vigilance, if you use it at all. Before you know it, it will have grown by leaps and bounds and will have smothered your rhizomes, and there goes your bloom for next season. (It also looks mangy during the cold months of the year, even here in Zone 9 where we do not get snow. We grow the large leafed cultivar 'Helen von Stein'.)

2. Iberis (Zone 3 and warmer) can make an ideal companion plant, so long as you prune and tidy it after flowering, and keep it within bounds (not hard to do). It is in bloom when the early and mid season TB irises are in bloom.


Shown here is 'Arctic Express', with Iberis behind it

3. Another good companion plant (for Zone 7a and warmer) is Tulbaghia violacea or Society Garlic. It begins blooming roughly the same time as the early TB irises do.


Shown here is 'Arctic Express', on an earlier day and from another angle, with the white flowered Society Garlic 'Pearl' behind it

The main lesson I learned this year is not to plant precious, wanted TB irises of the same color range in one bed... like a 'pink bed'. TB stalks tend to lean into each other and unless your irises are planted three feet apart or more it will be a task to recognize each bloom without an examination of the base of the iris. What waaaasss I thinking

Poly:
I found out the hard way that #7 is very true! I will use much larger and deeper pots next year if I pot any!

On #2 I use a much deeper ceramic pot than the plastic iris pot and I place bricks in the bottom of the ceramic pot before putting the potted iris in it. This helps.

Don't use eucalyptus mulch in your iris beds. It alters the composition of the soil in a bad way and reduces the flowering and the number of increases from the mother rhizome.

To trim or not to trim, that is the question. In the fall, I have both trimmed and not trimmed to see what would happen. I am now firmly in the trim camp , due to the cleanup required the following Spring in untrimmed beds.

Blessings

I am firmly in the untrimmed camp. I have far too many irises to trim and I would have to do it in the late, late fall when I have so many other garden chores. Then in the spring I would still have to remove the short pieces of leaves from the rhizome. Seems like double work to me and in my short winter periods I may be reducing the benefit that the iris leaves provide in the fall.

My lesson #1 would be to either pot or pin down irises planted late in the season to avoid heaving.

Lilli, I put a brick over the rhizome to hold it down. Not only does the brick keep it from heaving during extreme temps but animals cannot dig/scratch it out of the soil. The brick does not seem to hurt it and it still gets its nutrients and water.

grannysgarden said:On #2 I use a much deeper ceramic pot than the plastic iris pot and I place bricks in the bottom of the ceramic pot before putting the potted iris in it. This helps.

We have gravel left over from some "mining operations" (long story, involving online purchase of gravel ore from gemstone mines for DD (B.A. in Geology) and me to play with) that I have been using in the bottom of the deep pots, and also in the bottom on some plastic veranda boxes. Large sized wood/bark mulch might work too, but that would degrade over time, whereas brick, rocks, and gravel will not.

yes, and rock, bricks and gravel are heavy enough to keep the pot from falling over. Critters lurk in damp woodchips too.

Extremely helpful suggestions, everybody.

Another thing (Marilyn gave me a great platform from which to vent, LOL), when planting similar colors be sure and choose ones that do not bloom at the same time. If you choose six blues and they bloom at the same time you cannot enjoy the unique beauty each one brings. I have (again with the pinks, because I loooove pinks!) some that bloom very late. Usually these are the only things blooming in my garden at the same time. I need to find another 'opposite' color for very late bloom.

If you want to plant irises so that their colors compliment each other you must make sure the bloom times coincide. (I know this seems like a given, but....... )

Might seem like a given, but I'm sure many of us have made that mistake
- or the irises have simply decided to ignore their appointed bloom time!

grannysgarden said:...when planting similar colors be sure and choose ones that do not bloom at the same time.

I can see the point of not planting a sea of pale blues (or pinks), but what about mixing light blues and dark blues (or lavenders and purples, or pinks with purples)? With maybe whites or creams thrown in between? Keep the similar colors non-adjacent, break them up with the other color (or two).

grannnysgarden said:If you want to plant irises so that their colors compliment each other you must make sure the bloom times coincide.

I suspect that if you want to plant them out "right" the first time, the only way to really be certain of the coincident bloom times is to first grow them out in pots. I planted 'Nordica' and 'Peppermint Cream' next to each other. Both are midseason. 'Nordica' bloomed first (two weeks ahead) and is winding down now, and 'Peppermint Cream' has just started. I really wanted (and expected) that they would bloom more together. As it is, I think that I am going to take 'Peppermint Cream' (which I have less of than 'Nordica') out of that corner and just give that space over to 'Nordica'.

I finally took a picture to illustrate one of my points in the first post, co-planting an annual in the pot with the iris. Don't try this in a 1 gal pot - the iris needs all of it. You must use a #2 or bigger pot. This is the (early snail warning system) Chrysanthemum paludosum with 'Double Agent', in a #2 pot:

Marilyn said.....

I can see the point of not planting a sea of pale blues (or pinks), but what about mixing light blues and dark blues (or lavenders and purples, or pinks with purples)? With maybe whites or creams thrown in between? Keep the similar colors non-adjacent, break them up with the other color (or two).

Absolutely right, Marilyn. If you have a big enough space and enough various shades of the color you choose and whites you can keep them separate. And that is lovely.



That is a fun garden idea if you have enough irises and cannot find homes for them. You can use them to create a bed of mixed hues. If one or two gets lost in it you have your other clump in a regular bed.

That sea of blues is stunning Bonnie

More very helpful thoughts.

with Robin and Andrea!

My blue(ish) iris bed is a mixture of light blue, I. germanica, purple, white and blue/white in various patterns. Plus some little ones in front of course!

Poly, I like your early snail warning system!!