We put laicce under the steps going to our pool mostly to keep the animals out but if you plant ground cover it can go under there oo. I live vinca for that type of space it loves low light grows well and stays evergreen with som epretty flowers in the spring . It can bea bit invasive but easily cut back to control. We did our area of grass in our yard in gravel we have a ton of trees but the blower gets them out from under all the stuff planted along the edges and off the gravel pretty easiliy but it is flat . I think with your slope vinca is the way to go. Keep it under control if you have beautiful landscaping near it . I find a good haircut once a year is good . I live in BC zone 6 so it is green all winter and this is the glory in the spring. If you live very near a woodland then it might not be agood choice but I love mine

If you have a concern about leaves in the fall... be aware that any groundcover can catch and hold the leaves. And it's not necessarily any easier to clean up than if you used stone. And ground covers have their own upkeep.

Why do you want to leave the area open?

You'll find it hard to get anything to grow under the deck. It's too dark and too dry. Anything which managed to cling on to life would be scruffy and sick-looking. I'd look for another solution.

You would be shocked at what can grow under a deck. Decks aren't solid like porches. Rainwater is meant to drain between the boards. And unless it is on the north side of the house, or closed off somehow, there is definitely enough light for some things to grow.

Which gets us back to the perennial question of where in the world is this deck?

Your photo doesn't illustrate how this area relates to the house. Does it appear unfinished without some porch skirting?

If you use landscape fabric and river rock, a leaf blower can take care of leaves and the rock is less hospitable to animals

We are in south central PA, zone 7B. THe deck is on te northeast side of the house. I don’t care for lattice (though the horizontal boards are appealing) and thought closing in the deck would retain dampness.

Wet leaves will stick to stone. I do like vines but think pachysandra would be easier to manage over time, particularly in this application.. I have patches of pachysandra that are never raked and just gobble up leaves.

We have plenty of critters that take refuge in the ground covers and that doesn’t bother me. There must be reasons why I don’t see more decks with plants underneath.

Perhaps I should enclose the underside with evergreens but that still leaves bare dirt underneath to erode

Additional to what is suggested in this article, I planted euonymus on the support columns.

https://www.landscape-design-advice.com/plants-for-under-a-deck.html

I have different varieties of euonymus climbing all up and over my pool fence. Trim it once a year.

One of my favorites:

Dark Wintercreeper ("Radicans")

This cultivar, named “Dark Wintercreeper,” is the one that most resembles ivy. It grows very densely, is reliably evergreen, at the same time particularly frost resistant. In spring and summer, the foliage is medium green, turning to dark green with a reddish 'tan' in autumn and winter.

If you're set on a groundcover, take a look at Geranium macrorrhizum.

The thing about having nothing growing under there is you can 'weed' it with herbicides. That is probably the appeal of keeping it empty.

Can you stand up under there? Because a lot of “ groundcover “ things , if they do grow, would need occasional trimming to keep from getting too unruly. Though less likely that they would grow so vigorously.

We have lattice and small gravel under the deck.

If you have ground cover in such a protected place you'll have critters.

I have that vine and pachysandra in zone 4 and no way would it grow under a deck. It sounds like you know people with similar set up. Why not ask why they don't skirt their decks. Keeping it open sounds like an invitation to collect leaves if not critters. Heavy landscape cloth with large river rock would keep weeds down. That's a lot of area. The last deck we had we turned into a play area. Sandbox under the decking and swing hanging from the skirting.

@BeverlyFLADeziner and @marmiegard_z7b we have plenty of critters already living along a creek. It is the only downside of ground cover under the deck that I could think of.

@arcy_gw, I don't know others with a similiar situation. Thus, why I ask here. I can stand under the end of the deck and, no matter what we decide to do, we will have to stoop once or twice each year to get close to the house.

@BeverlyFLAdeziner, can you please share a photo of under your deck?

Since you are near a natural area, check whether the suggested groundcovers are invasive where you live. It is such a shame to see natural areas overgrown with non-native species that choke out native plants such as trilliums. They provide no food for wildlife. Where I live (Toronto) vinca, pachysandra, English ivy and wintercreeper/euonymus are invasive. They spread by seed too, so even if you are not that close they can be the source.

The easiest solution is to skirt the deck. Plant evergreens around it if you like the look. You won't get enough rain through the deck gaps to wash away the soil. We have had our deck for 35 years and it has a good slope underneath. The soil is the same as it ever was.

Plant a row of bushes along the front--in the sun-- like you already have in some areas. Then plant ivy on the slope. I'm pretty sure Ivy would grow with such little light.