Yes, they are easy to germinate. I collected mine from my own plants.

They must seed pretty easily. I started with one plant that grew tall and tipped over by seasons end. The next spring, wherever it touched the ground, another plant grew. I dont mind at all that it now fills most of that bed. The soil is quite sandy and poor. All fill hauled in by the home builder, full sun, South facing. Now I cut the plant way down in late Aug and get another flush of bloom this time of year.

While species Agastache have been reliable performers/reseeders in my zone, I've not found that any of the cultivars have returned after a season or two. I've grown any number of them from seed via winter sowing without seeing any success in their second year. Even the volunteer Verbena bonariensis that showed up in my garden a couple of years ago has disappeared. Normally seed-grown winter sown perennials are hardier than nursery-grown plants but I haven't found Agastache particularly hardy compared to other perennials that are more zone-appropriate. Wish I could be of more help. I love RS and have paired it with Gaura lindheimeri in my cottage garden bed but thanks to wet conditions it hasn't prospered. In my garden the RS either gets full sun + too much water or appropriate moisture + too little sun. The zone thing may still be a problem but check out Tricyrtis hirta/toad lily. Mine are blooming now in both full shade and part sun--might work for you. Missouri Botanical Garden website rates it hardy to Z4. The flowers are speckled purple & white. Oh, and the bees love them.

Steve, I don't understand why you are using trellis's. None of the herbs you have have vining tendencies. If you are using the trellises for support, I'd recommend trimming back the plants instead to put more energy into making roots and filling out the plants themself. If you don't mind what the pots look like think of recycling 2 liter soda bottles, gallon jugs with the tops cut off or anything slightly resembling a gallon size pot and poke 4-5 1/4" or 1/2" holes in the bottom for drainage. If you have a recylcing center near by I've never found one that doesn't mind you going through it for containers (this is from experience) and they are free. Yard sales are another great source of cheap pots, I just bought a barrel, square plastic patio container and a 3 gal foam planter for $3 (don't be afraid to bargain...they were asking $5 for 2 of the pots and got them for $2. But do save your money and use a soil less potting mix preferably without fertilizer (the fertilizer washes out after a couple of waterings anyway). Daisy, I disagree with keeping the soil permanently moist. This may be so until and only until the plants are established, once the roots have developed enough that the plant is thriving allow to dryout between waterings. Many an herb has died from over watering, herbs prefer the soil to dryout between watering.