Adding topsoil on a slope

[Than]

Has anyone got experience with adding topsoil on a hillside property? Mine is on a slope but surrounded by a concrete wall which holds the soil and makes it almost flat but not entirely. There is still a smooth decline. I am wondering if the added topsoil will be washed away when the rains start in autumn as it may not have enough time to compact, plus the newly planted trees won't have roots wide enough. If anyone has tried something like that, please share your experience.

[BayAndroid]

I'm facing a similar situation, I'll be interested to hear people's opinions. My personal thought is to use large rocks to create some stabilization anchors and then maybe a fast growing ground cover to hold the rest in place. 

[happypalms]

I live on a hill. Simply use the terrace method. Using logs or rocks or any material you choose to use. Place the materials at the position you want then backfill. It’s a great way to garden almost like swails on hill. 

[Than]

3 hours ago, happypalms said:

I live on a hill. Simply use the terrace method. Using logs or rocks or any material you choose to use. Place the materials at the position you want then backfill. It’s a great way to garden almost like swails on hill. 

But doesn't that mean that water pools more when it rains? That could be bad for our cool and rainy winters.

[happypalms]

44 minutes ago, Than said:

But doesn't that mean that water pools more when it rains? That could be bad for our cool and rainy winters.

Not necessarily if you have good drainage. You can put an ag pipe in the soil for better drainage or backfill with a little gravel.

[Harry’s Palms]

After 28 years of amending the soil on our huge slope , it has really kicked in over the last 4-5 years . I can sink a shovel in just about any where to plant a new palm . We have a very steep slope and it was very challenging to amend and irrigate effectively. We started with massive amounts of wood chips and organic soil amendments, then covered with woven jute rolls to hold it in , until the jute rotted and became part of the hill.It was a ton of work but it really helped . Then , every year I replace and refresh the soil and wood chips up on the flat area around my palms and flower beds , I take that faded , stuff and distribute it on my hill . I don’t fertilize anything on my hill . I water with 3 banks of sprinklers about twice a week in the warmer months , more if needed. The slope is south facing so it gets near full day direct Southern California sun. Terracing is probably the best way but we didn’t want to spend that amount of money on the hill, just wanted to grow some hardy palms . Harry

‘This is looking southeast, behind that large Butia is a large Brahea Edulis both grown from seedling stage

Looking up towards our house from the southwest side about 2/3 down the hill

Livistona Chinensis , bullet proof 

Almost at the bottom of the hill , standing under the large Brahea Edulis to get a look at the B. Armata . L. Chinensis to the left

A closer look at the Armata

Two years ago I got my hands on this Livistona Australis in a large 5 gallon pot . It was badly abused and only had 1 healthy frond , now thriving! I dug a huge hole in less than 1/2 hour to plant him. When we first bought this house it would’ve taken hours , like breaking concrete! 

[Than]

8 hours ago, happypalms said:

Not necessarily if you have good drainage. You can put an ag pipe in the soil for better drainage or backfill with a little gravel.

I think I'll go for that. It will also look better with terraces. Thanks a lot

[quaman58]

I have lots of experience with this.. Everywhere I plug in a plant, there are at least a couple of moderate rocks placed on the downhill side of it. Tremendously effective at holding water and soil. Once the palm becomes established, the rocks become less important, however they continue to act as a dam for soil and much. Regarding adding topsoil, I only add when planting a new palm, since I've got a big hole to work with. After that, it's mulch every 2-3 years if possible. Using sprinklers has pros and cons: it's pretty ineffective at deep watering, which means palm roots will remain pretty shallow & close to the surface. However, it is more effective at turning mulch into compost. Drip is way better and keeping plants robust and growing but doesn't spread much beyond a given zone. In a perfect world, I'd have both, the drip system taking care of about 75% of water needs, with the sprinklers coming on perhaps every 3 days in the summer. Whatever terracing I have is simply so I have a path to access the garden. 

-Bret