In nature, plants grow on a slope all the time. So yes, you will be able to get plants to grow on this slope.

That said, the plants' roots will always get less moisture because the rain will run off. Once the roots are established and deep (if you are planting shrubs) then this will matter less.

If that is landscape fabric, won't the mulch just slide along it and gather at the lower end? I am not a fan of landscape fabric. Just add a thicker layer of mulch.

The Mulch should be fine, if it does slides I’ll add a 4by4 in the middle.

It’s 5x more work trying to dig the slope to make the 4by4’s straight in step method.

Does this look asthetically bad ?

Reasons #1 and 2 would argue against using the 4x4's at all, either singly or in step. And there is also NO need! Plants grow naturally on slopes all the time and need no help from humans to do so :-) Jut dig a hole and plant. You can make a shallow moat at the downslope edge of the planting hole to slow water movement. NO landscape fabric!! It doesn't stop weed development and it can impede water percolation and oxygen exchange at the soil surface. And it is a major PITA to work around down the road. Just make sure all the weeds and unwanted brush have been removed first and then lay a good thick layer of mulch after planting.

I think different than yours, but idea -- river bed of rocks?

An extensive landscape project with stonewalls, patio, dry river bed & more · More Info

I agree with Gardengal. Landscape fabric is a PITA. Expensive, a pain to put down, and doesn't do what it promises (stop weeds).

As it happens I'm planting on a slope right now too, on my front yard. It's about as steep as yours. My back yard has an even steeper slope that I planted years ago. Never used landscape fabric, never had a problem with soil washing down.

Previous owner installed fabric, and what it does do is prevent roots from deepening, and they are easier to pull out.

Just put your plants in and forget the boards.

For a lazy person you are making a lot of extra work for yourself that is not going to turn out well and will end up making more unnecessary work for yourself which all just screams #2.

some ideas using Maiden Grass & Ilex 'Maryland':

What are you wanting to plant?

Wood rots -- even treated wood.

Consider landscaping edging buried in slits in the ground that could be easily pulled up and removed, if you wish, once your plants are well rooted.

https://www.walmart.com/ip/Master-Mark-Plastics-93340-Terrace-Board-Landscape-Edging-Coil-3-Inch-40-Foot-Brown-Provides-textured-wood-grained-look-your-By-Brand/606844303?wmlspartner=wlpa&selectedSellerId=11241&&adid=22222222227428490549&wl0=&wl1=g&wl2=c&wl3=512103625887&wl4=pla-1211791077093&wl5=9011062&wl6=&wl7=&wl8=&wl9=pla&wl10=117437053&wl11=online&wl12=606844303&veh=sem&gclid=EAIaIQobChMIy6jNmZWE8AIVFQiICR3dRA6jEAQYCCABEgJo9fD_BwE&gclsrc=aw.ds

Will either thrift or phlox or some other landscaping ground cover that blooms seasonally grow well where you are and suit your purposes?

An even better idea to create your planting beds would be bury brick or pavers so only their tops show to create an outline for your planting area. You could add a few within the area downhill of any plant that needs that extra "hold" until its roots get established. That would help hold the soil in place and you could mow around it with the tire of the mower on the brick/paver.

Another idea for edging for your planting bed is to dig a trough about 4" wide and 6" deep and fill it with concrete to create a curb with only the top showing..

Sorry all, I am sold on landscape fabric. I am in NJ and the 5 plants that I can grow here without hungry deer eating them grow fine on ground under landscape fabric. It’s just not worth having to week all the freakin time without the fabric.
@suezbell, I am trying to do a diy low maintenance to give my border a definition. I can’t handle concrete or brick. I get wood rots, but the plastic edging looks terrible in straight lines. I want definition and this 4by4 is giving me that.
@calidesign I am looking for definition and that’s why I want the boards.
@christopher that’s for the criticism, without a suggestion tied to it, it’s not of much use.
@everdebz this is certainly not diy for me.
@dig doug’s designs this is fantastic, but it would take me so long to prep the soil and land to have plants like this. I can easily put three of four - deer proof plants out of pots under the weed fabric and it will look way better than the 5 ft long brush.

The question I had is, will the 4 by 4 look ok sloped or should they be horizontal and stepped.

Much appreciate all the feedback !! Thank you for spending your time on this post.

I get it. But recently I noticed large stones at the store. If delivered you plop them in a meandering path... within bounds you need for the project...

If you want definition for the edges, you can use metal edging, which basically disappears, or use natural stone edging. You can place the stones yourself, and it would look so much better backing up to your natural spaces. You can also curve it around so you don't get that straight line that doesn't make sense.

Happy Hollow · More Info

I have a slope in my back yard with a retaining wall. I am SORRY that I didn't use your idea. My slope is well planted with shrubs, evergreens, groundcover BUT I still have erosion. I think your idea or at least something like ONE board across the slope or big rocks will help trap some of the moisture for the plants near the top of the slope.