I think the Hakonechloa would really struggle with the thick roots of the magnolias. I've found that under my M. stellata, bulbs do very poorly, and the only groundcover that has really worked is Geranium 'Biokovo'.

I can't speak to magnolias as I don't have any. What I do see around here is not in bloom for very long (which is why I don't grow them. ;o) I think what would make a bigger impact for your front yard is a large berm or raised bed set away from the tree. That would still break up the lawn but not compete with tree's root or get shaded out. Your only limit is your imagination. I'd start with bulbs and assorted perennials that bloom at staggered times into late fall - you can even add small flowering shrubs or roses. I can't think of any established perennials that wouldn't need some division every year. If you already know this about magnolia, you'd be safer to avoid planting near it. There are lots of books that can give you creative ideas. I find it helps if I see photos. Keep dreaming!

Oh dear, there goes my mid-winter daydreaming bubble..lol.
Laceyvail, did you try to establish the bulbs and other groundcovers after your M. stellata had been established? Could that make a difference if you planted perennials and bulbs at the same time as the tree goes in? I wonder how the British gardeners get their primulas, scillas, and other early spring flowers to grow so well right beneath magnolias.

Nancyd, I don't know if I am going to plant the magnolia tree or not. Every year around this time I hunger for flowering trees, and I don't have any magnolias in my yard. Of course, once spring is over I also wish I would have planted more summer flowering shrubs and trees... sigh...so many plants so little time and space.
Anyways, thanks for your answers. Has anybody else on here have experience with underplanting magnolias? What grows well for you?

A couple of years ago, I took a picture of an old Elizabeth at Stonecrop. There is nothing growing under that tree. Nothing. Zip. Zilch. Nada.

I have an old M. x 'Elizabeth' and it has always been underplanted with evergreen Azaleas, which bloom about the same time as the tree.
I also have 4 Evergreen Southern Magnolias (M. grandiflora), that were limbed-up to permit walking under them. The ground under those are competely covered with perennials, shrubs and bulbs. Rhodies, Azaleas, Daphne, Hosta, Ferns, Carex, Epimedium, Hydrangeas, Asarum, Helleborus, Asiatic lilys, Scilla, Sternbergia, Sedum, Liriope, Woodland Phlox, Brodiaea, Thalictrum, Osmanthus, Ilex, Camellia sasanqua, Viburnum (I'm sure there are others that I can't readily recall).
I also have 2 Star Magnolias and several Magnolia x soulangiana (Saucer Magnolias). I have had no problem growing any shade tolerant plant under any of those. Such as:
Arum, Arisaema, Cyclamen, Calanthe, Helleborus, Trillium, Daphne, Asarum, Erythronium, Iris japonica, Ferns, Crocus, Hosta, Hydrangea, Hepatica, Geranium, Campanula and more.
Under one old, very large tree, I have 2 dwarf Japanese Maples growing.
As long as adequate moisture is available, you can grow whatever is suitable under Magnolias. I have been successful for 40 years. Whenever a Magnolia feeder root becomes entangled with an underplanting, I just cut it out of the way. Has never affected any of my trees!

I think if you plant right inside the dripline, you can place an edging of annuals, as their roots won't get so big, and then use perennials when the tree is large enough to cast some shade. I like the idea of the hakone grass and the blue hostas! We have deer, so I actually have to move my hostas to the backyard where it's safe, LOL. Or use an edging of calamint (Blue Cloud), my new favorite perennial edger, it has tiny blue, fragrant flowers and is tolerant of dry soils. They would contrast nicely with the yellow blooms. p.s. The cultivar name is actually 'Butterflies'. :)

Georgia-Rose - I love your suggestions. Some are not hardy for my area, but they would make a great addition to the magnolia bed. Thank you!

Prairiegirl - upps, thanks for pointing out the misspelling... can't believe that slipped through...lol. I also like your suggestion of the calamint. I am not familiar with it, but from the descriptions I just read it sounds great. I may need to try that. Thanks a lot!

On no! I made a mistake, the calamint may not be in bloom at the same time as the magnolia is, this is my first year for it (planted last summer), but it is still a great edger! :)

White daffodils... tough bulb (or whatever) and the white will compliment the yellow of the tree's blooms without competing against it. Assuming, of course, that the varieties you pick will bloom at the same time. Even so...