This is my 1st year for anise hyssop.
1. Will it flower abundantly the 1st year when direct seeded in May?
2. Does one seed produce one stem, or is is a 'cut and come again'?
I have one anise hyssop in my herb garden. It was planted from a 3 inch pot early last spring and it branched out and produced more than one bloom and bloomed several times during the summer. I cut the flowers back after it bloomed. I do have a long growing season here and it is planted on a south facing hillside.
Agastache 'Blue Fortune' is the hardiest (zones 4-9) Anise Hyssop most commonly grown as a perennial for cutflower production here in the Upper Midwest. This plant is a hybrid of A. rugosa and A. foeniculum. Bareroot plants are
available from Walters Gardens in Michigan.
But, you're referring to the Anise Hyssop (A. foeniculum) seed in the Johnny's Seed catalog (or a similar source), it is considered a "tender perennial." Johnny's says they are hardy in zones 6-9. They aren't hardy here. We would treat this one as an annual; and, we would start the seed in the greenhouse the first week in April (just like salvia farinacea).
It's now April!!Wow. What happened to March? Anyway, we would then plant good size plugs (deep 72s) out in the field mid-May. They produce many, many stems for cutting; and, we'd start harvesting mid July. If you're direct-seeding,
I would guess harvest may be set back a couple weeks.
FWIW -- The stems also require special post-harvest handling with our humidity here in the Midwest.
My agastache foeniculum bloomed first year from seed for me two years ago. While it is not a hardy perennial, if you leave some seed heads it will indeed reseed. (Or just save some seed to sow again)
As a matter of fact, I did not grow it specifically as a cut flower the first year, and thought the dried seed heads looked nice, so I left them. Last spring I was overwhelmed by the amount of agastache seedlings everywhere. Last season I was much more careful to dead head whatever I didn't cut, and to manage the seeds, as opposed to letting them fall where they may.
I am suprised to see that your agastache foeniculum is not hardy in Zones 5 and 6 because all the hardiness info for it says it should be. It is a native plant and its native range includes most of the northern states. I have seen it growing in my neighbors yard and it returns each year. Maybe it is not hardy because of your garden conditions, it naturally grows in well-drained soil so possibly it was in too moist of a soil? I know my neighborhoods soil is quite sandy, and very well-drained. Just thought I'd add my thoughts so others in Zones 5 aren't deterred from this plant after reading these posts.
Here is a link that might be useful: Distribution Map