I have received a detailed catalog from a well-known nursery, and this is what I’ve found about sowing hibiscus laevis:

Some species need to go through cold stratification to break dormancy. For these species, fall provides the conditions necessary to break seed dormancy and the following spring gives the seed the nutrients it needs to germinate. Hibiscus laevis is one of the species that germinate after a period of cold/moist stratification. You do not need to do anything if you plant them in the fall. Ideally, native wildflower seeds should be planted following their natural schedule, which means they make soil contact in the fall, and since laevis is a native species, late fall is the best time to sow the seeds. Over-wintering is simply nature’s method of breaking dormancy for species requiring cold stratification.

Until you are ready to plant or apply pre-sowing treatment, store the seeds in an airtight container under refrigeration (33-40 deg. F). Avoid rapid or frequent temperature changes during this time.

If you are going to go the spring planting/cold, moist stratification route, wait until approximately 60 days before the date you plan on sowing before you apply the pre-sowing stratification treatment (I would figure about 60 days prior to shortly after the average date that the last killing frost hits your area and begin stratification on that day).

To stratify hibiscus laevis seed (for spring planting):

1) Mix seeds with equal amounts of damp vermiculite (moist, but not so much that water will squeeze out when squeezing a handful). Silica sand is used by nurseries for small quantities, and can be purchased at a building supply store, or just go with vermiculite.
2) Place mixture in a labeled, sealed container and store in the refrigerator at 33-38 deg. F.
3) Leave for 60 days. If sprouting occurs during stratification, plant immediately.

So, in short, late fall would be the best time to sow if you don’t want to go through the self-induced stratification process. Since they do require cold/moist stratification, I wouldn't be concerned about temps not being above 70 deg. Either plant in the fall and let mother nature do the rest, or stratify them as mentioned above and plant them in the spring. If temps are still a little cool when you sow them, it shouldn't be a problem. I would think they would just wait until the right conditions to germinate.

As for how deep, as with all seeds, sow them shallowly (I would mix some peat moss in the soil as well) and keep seedlings carefully weeded and water periodically to help establish them.

As far as removing the seed from the pod or not, I would remove them, simply because that's the way most seeds are sold when bought commercially. The pods have to break open in the wild to distribute the seed, so that's what I would do.

If you are planting in an area that could wash out, as I am, or you don't want to bother with heavily cultivating an area with a lot of weeds (like mine), you might try something like this:

Cultivate an area of your yard like an designated area of your vegetable garden, etc., and plant the seeds there in the spring with the intent of transplanting them the following fall into your wet area. Just remember the hibiscus likes it wet (and relatively acidic)!

Another possibility might be to get some topsoil from a local supplier or obtain some soil from your property that is between 5.5 and 7.2 for H. laevis (if you get commercial topsoil, make sure you can test the ph before you buy it). Fill some "kiddy pools" with the soil and just plant the seeds in them in the spring after danger of killing frost has passed. The idea is to mimic the natural habitat of the hibiscus or create an environment that retains a plenty of moisture in the soil so you don't have to water constantly. (I'd put my drain holes on the sides of the tubs, rather than in the bottoms, so they will retain plenty of water) Anything that creates a very-moist-to-wet environment should work, or just make sure the soil doesn't dry out. Just as with the garden plot method, transplant the plants into their final destination the following fall.

If you can pre-start them, you're really getting a head start by planting actual plants into your area and not taking a chance on the seeds washing out or being choked out by other native vegetation (a green house would be ideal, but if you're like me, it's not an option).

P.S. I realize that the original post was started four years ago, but I found it when doing a search for hibiscus laevis and this is more a "note to self" than anything, lol...

Anyway, that's where I'm at right now with this. Instead of the late fall planting, I'm going to try something like this and hope to post the results here in a year or so with some pictures -- if there are any to post (knock, knock).

--John

I received my hibiscus seeds in the mail this week, and now it looks like I'll be investing in some kiddy pools, a couple yards of topsoil, and some ground rock sulfur, and plan on stratifying the seeds per the instructions above and getting them started next spring.

I'll post any other developments here :)

Now...I just hope the sprouts don't get unearthed by excessive water before they have a chance to take hold. If that happens, I'll be buying some more seeds and trying again :-)