I am not in your zone and don't have alkaline soil. But I do have clay soil.....clay soil holds moisture longer, and therefore, you can experience more soft rot in the spring. An ammended raised bed on a hill or that drains well would be ideal.

As for early, mid and late season varieties.....well I have put the same varieties in different parts of my yard and they bloom at different times. Some have bloomed a month apart. Shrug. All areas are full sun.

The miniture and dwarfs bloom first, then the intermediate and border bearded bloom closer to the tall beardeds or close to the same time.

Division for bearded iris is every 3 to 5 years. This depends on how fast they multiply. Some varieties multiply faster than others. Garden soil and conditions are also a factor. When the iris look crowded or don't flower as much, it is time to divide. Also if the flower stems stay low in the foliage....is another sign it is time to divide.

Blooms last for me....one to three days.....but most iris branch, so the bloom time of a clump can last up to 3 weeks here. In warmer conditions they may not last as long. Hopefully someone else can answer this for zone 6.

Hope this helps.

Sierra

clay soil holds moisture longer, and therefore, you can experience more soft rot in the spring. An ammended raised bed on a hill or that drains well would be ideal.

===>>> iris love my mineral sand ...

it would be as easy as getting a few yards of course sand ... and simply piling it about 8 inches [after settling] deep ... and just planting over the clay ...

i dont know if it would be less work than highly amending clay soil ...

otherwise.. they are near bullet proof.. and relatively cheap.. just try some...

they are planted ON THE SURFACE ... no more than half in the soil .... but roots in the soil ... [you will really think it wont work. but it does] and basically ignore them except as babes.. in drought ...

odds are high.. you will succeed ...

and the easy answer is.. have you seen any in the neighborhood ???? and if so.. soil is probably not an issue ... other than the drainage issue ...

ken

Hi Ken,

Just a word of caution when adding sand to the garden. I have tried adding several kinds of sand....for me, it caused problems. Sands turns into cement. Cakes and crusts.....my iris were not happy. I had to get the iris out and redo those beds. Now if you add sandy loam, that would be perfect. But adding sand to clay did NOT work for me.

Sierra

i was a bit imprecise ...

i agree .... incorporating sand into clay.. is cement.. or adobe brick at best ...

all sand is not created equally ... i was thinking course sand with pebbles ... as compared to say or builders sand ... or play sand .. or a sandy loam as per above ...

way back when.. i dabbled in alpines ... i had super amended michigan peat soil ... and alpines do not like soil that hold water, especially in winter ...

it was suggested by local expert sellers.. to simply get a yard or two of scree .... and make an 8 foot by 8 foot bed on top of nothing else .... i think i used some 8 by 2's .... filled it up.. and continued to make a small mountain ... too bad it was pre digital pix days .. and i moved ...

so my point.. which i inartfully explained ... is to ignore the clay.. if it is that bad .. and simply go vertical ... but you have many options of what to put in the raised bed ...

as to which iris... there are about 3 basic types... one has bog tendencies.. i have never messed with those ... japanese maybe???

the second is a clumping type ... nearly indestructible ... almost looks like a grass.. but for the deep purple purple flowers.. you might get confused ... [lol.. i dont mean the experts] ... siberian i think ...

and then the bearded iris ... the huge lemon scented flowers that grow on top of the soil ... also nearly foolproof... dig one up right now.. and leave it in the garage until spet.. and most will live [unless of course you pay 50 bucks for it.. then it will commit suicide ...] ...

but for the bog ones that require near constant deep moisture .... aka bog ... the other are what i call driveway plants.. where they can be forgotten for long periods on the driveway .. and still survive ...

the OP.. should simply buy some siberian ... [or beg them off a friend] .. and some tall bearded .. and give it a go ... and should remove all fear or worry from the equation ...

as to spreading.. its not really an issue.. dig and divide when necessary .. at best every few years .... and then share with friends.... or at that point.. try them in the bad soil.. and see if this was all for naught ...

in my opinion.. they all have short blooming seasons ... unless there are certain ones that have extended bloom season ... and i would leave that to others ...personally i have never seen a reblooming iris.. but the warm zone peeps talk about them ...

ken

Here is a link that might be useful: scree