The purpose of lasagna is to use newspaper or cardboard to kill the weeds, grass in the area you are going to plant. It would have been better if you had laid the newspaper then put your soil on top. The paper breaks up but would have smothered the growth underneath.

Short answer is no you did not create a lasagna bed. What you will have is a rich planting area but you will probably have a good bit of weeds coming up. What I have been told is if you till you will wake up the weed seeds.

All is not lost to weeds! Might have been too early for some to be sprouting in your area, but you can make sure they don't by using newspaper as mulch between the plants & mulching planting bed to make it easier to pull the newly blown in weeds that sprout. There's not any right way to do this, but some ways are less work for you, which is the spirit of the lasagna garden.

Sounds like you're ready to plant, don't bother mixing layers at all. Let the worms do the work for you. After all you added topsoil & peat, which are ready to plant materials.

Not sure if it's hot yet where you're located, but watering in the plants or puddling in the parted layers will help your moisture loving plants get a good start. If under overhang have a watering plan if you don't get weekly rains.

Pull & push apart the layers to plant. I like using the hand cultivator (3 pronged) tool to do this. If layers aren't deep enough to accommodate depth of plant roots you can add more material such as coffee grounds and compost because neither will damage the roots.

Purchasing weed free compost is a great way to fill in around your plants to make sure no weeds are surrounding crown & up under your arching plant leaves. I'd go probably 12" around each plant because the plants you've listed are hard to get up underneath once they grow a bit.

Then after you've finished planting you could add your weed barrier of overlapping newspaper at least 10 sheets thick to smother what weeds sprout. Perennial weeds may need to be pulled. We have creeping buttercup & dandelion in our area that manages to grow through the edges in places, but pulls up easily through the mulch.

Top off the paper layer with 3-6" of whatever mulch you desire. Additional coffee grounds on the paper prior to the mulch will help reduce the mulch amount required & weigh down the paper. As long as you cover the top 1" of the bed with a uniform material no one will know you've tucked in coffee grounds, kitchen scraps, & torn household papers (including kitchen napkins & facial tissues). As long as you bury the layers you can add anything underneath that is compostable green/browns.

Just keep mulch off crowns of the plants & you're set! I've done this several times and it works!

A few more thoughts --
-if you're now short of material volume after planting it's okay to leave the bed for awhile while you gather more materials to level it out. As long as the plant roots are covered & moist the plants can establish.
-call ahead to coffee shops to ask them to save grounds for you to pick up later that day. Sometime around 10am is the best time for me to make calls & then go out for errands & pick up. Some days I stop at 3 coffee shops while doing other errands & my trunk is full of grounds & groceries have to go in the back seat!
-composting parts of the layers are going to shrink anyway, so it's okay to pile up higher than you desire the final bed to appear.

If you didn't have grass or weeds to start with, I don't see why they would suddenly appear through 8" of "stuff" in such heavy amounts that you would need any newspaper barrier. If any unauthorized sprouts appear, just pull them.

I agree with your process except a couple small details. I would skip the peat. It's very hard to get it wet again once it becomes dry, and never seems to go away. Some people like it, though.

The leaves would, in a natural setting, be on the surface of the soil, not under it. Totally agree with corrine - I wouldn't till. That would alter whatever work the worms & microbes have been doing to distribute materials where they should go. Keeping it moist will help the organic materials decompose ASAP.

You didn't say what kind of ferns, but I don't think hosta and astilbe will live with zero direct sun. Yes, they like shade, but not zero direct sunlight at all. Maybe folks with experience of this type of condition could suggest plants that would do well, or tell you they'll be fine. I've never had a planting in zero sun, so just don't want you to waste money if these plants wouldn't be happy.

Are you able to make a compost pile for your kitchen scraps and this fall's leaves?

corrine, I would be careful using coffee grounds under the surface in contact with roots. They are somewhat acidic and are usually applied to the surface near acid-loving plants if not composted first.

Thanks purpleinopp for the warning about the coffee grounds being acidic. Your concern make sense, but the labels from St*rbuck's bags state that the brewing process takes away the acid & my experience with the coffee grounds has so far been favorable.

I began using it as mulch around tomatoes & strawberries quite a few years ago, then added more in ornamental beds to extend my compost mulch, then as part of layers in lasagna style gardening creating new beds.

As long as you're using coffee grounds as part of the mix not planting in pure grounds it seems to work in my Pacific Northwest climate.

When you fork back the layers to plant in a pocket it is ideal to have some weed free compost to surround the roots if planting bare root plants. However, I don't always have enough finished compost ready to use when building new gardens & I've had success.

Just this spring I created 3 gardens here & another at in-laws home where they had creeping grass invading the bed, so we removed plants, mowed short, laid cardboard, replaced plants, & layered around them. We had limited materials at their place & no compost. Last year, we expanded a garden & made 3 more new ones including an herb garden with the layers.

There are books on Lasagna gardening to read if desired.

The only plant we've lost in this process was a lilac sucker from a plant swap in last year's expansion.

I know it doesn't make sense to put that stuff altogether. It stinks when you pull back the layers getting down into that 1st layer of manure trapped without air on the cardboard, but as long as it's a blend of ingredients it seems to work okay. Last year, I had lots of rabbit manure as well as poultry manure from backyard birds here. This year one 50'+ length of border we used goat manure + hay bedding, but let it compost in place a few weeks before planting then added layers as we gathered more things. Whatever I can scrounge up when building new seems to work. The top layer is mostly sawdust with guinea pig manure. Plants are blooming now: daylily, Siberian iris, perennial cornflower, hardy geraniums, veronica groundcover, forget me nots, etc. It works!