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.
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