You may find the lack of natural light a problem? Your example doesn’t look like it’s U.K. based and the plant choices look rather desert like. If the light is improved with the window then it may work.

Hi, if you search for “open staircase plants underneath” on Houzz you will find a few more example pictures of in-floor planters. You will also find lots of pictures of plants in large pots, so perhaps an alternative option. And of course the typical choice of a small console table
with houseplants atop would be the simplest of all.

Either way, the largest expense will be installing an open tread staircase. That might add enough light to the area to forgo creating a window, but obviously a window would be truly transformative.

If you are absolutely positive you want an in-floor planter, choose your tile first and then plan the layout and the dimensions accordingly so it’s easy to fill in and tile over later. Just buy and keep enough spare tiles. And perhaps also consult a structural engineer because you will need to dig out your subfloor and perhaps part of the foundation to create the planter, and of course it’s directly next to a structural wall.

If you are not totally certain, then why not have a raised planter made for the space? You could achieve much the same wow factor, maybe more depending upon the design and material.

Good luck and please do post a picture.

Not such a good idea in a typical British home I feel 😕

Far from being grim, I think your staircase is beautiful and looks to be well suited to your house. For a contemporary look I would remove all the clutter and furniture in the space, paint the walls, the ceiling and doors a crisp white, add some carefully designed lighting, and hang a huge vibrant artwork where the bookcase currently is.
(As to the cupboard under the stairs - it looks charming. If budget allows, how about installing a small window in there, that can be opened to air the space… and would treat you a to delightful, ‘secret’ glimpse of the view whenever you open the door?)

No, sadly, I remain in decision stasis with my hall and staircase! I have been investing my funds and brain into our outdoor space. My hall and stairs remain the same. I would like to replace the existing creaky staircase with a modern open tread version, open up under the stairs and place a window under, etc as mentioned. My husband is not with me on this. So, I remain open to creative ideas on how to handle this very uninspiring area.

So it’s been a couple of years and you say your hallway is still the same? Can we perhaps inspire and encourage you to make some changes so that although you can’t achieve your favoured option, you can at least feel happier in your home? Hopefully all the items that were there have found a home and are tucked out of sight? I would also remove the large bookcase on the right and the bureau on the left as they are darkening the space. I would place a slim console where the bureau was and put a lamp on a timer there along with some indoor plants. A large mirror will reflect your lamp. And a patterned rug in colours you love will make it more inviting.

Bureau is long gone and bookcase has a new home elsewhere. I am just holding out for the structural change. If I cannot go 100% down the original route, I think I will at least change the stairs. My thinking was similar to this image, although I have a window over the stairs.

I think your existing stairs are much nicer than your inspiration picture of oak and glass. .

Why not take out the existing under stairs cupboard and then see if electric lighting can give you the extra light source you want. A pale stone or ceramic floor will also help bounce light around even if you choose a strong colour for the walls.