Citrus tree help!

Hello all! I've posted once before. I'm an L.A. based permie and I have a client for whom I've planted two citrus trees, a Meyer lemon and a Blood orange. Both organic. Here's my dilemma: the area where I'm planting is on a hill. I've terraced the land. While forming the swale where I was going to plant the trees, I noticed that the earth underneath was full of, what I'm guessing, is limestone. Very chalky, large chunks. It seems to be what the hill is naturally composed of. I read that limestone is an alkalizer and that citrus trees in particular don't take kindly to this kind of soil. I informed the client and we decided to go ahead and plant the trees out anyway. I added an amendment (gardening soil from Kellogg. I know, I'll never use their product again, but it was cheap) and I used organic fertilizer under the root ball and mixed in with the soil. I planted them out about a month and a half ago and while they seem to be doing alright, there is a bit of leaf curl and some of the leaves have turned yellow and fallen off. I'm hoping this is normal transplant shock but my concern is that the limestone is going to kill them or seriously inhibit fruit growth. I believe the trees are already a year old. Are there any natural products I can be adding to the soil to neutralize the alkalizing affects of the limestone? Was it a horrible idea to plant these trees directly into the ground here? Any advice would be greatly appreciated. Thank you!

I am hearing in these parts that coffee grounds are a good amendment for this purpose, whether incorporated into the soil or laid on as a mulch. I don't get to town often, but when I do I try to check the grounds bin at Starbucks where they put them out for giveaways....

Soils around Southern California all tend to be alkaline, nevertheless, there appears to be no shortage of thriving citrus.

We have decomposed granite up here in the foothills. Soil does test slightly alkaline.

As mentioned, coffee grounds can help acidify, some pine needles will also help. Starbucks or Coffee Bean are good sources. Coffee Bean lets me bring a 5gal bucket with a lid and leave it there til its full.

Adding organic matter in general will buffer the effects of either too acid or too alkaline.

Where in L.A.?

Add some biochar as well. They even sell it at the grocery story. But you need to look for a sack of the "lump" charcoal, you want actual pieces of charcoal, not the briquette type with all the binders and "easy-light" chemicals.

The best way to apply the biochar to already planted trees is to make a slurry of it with some water in a blender. I keep an immersion blender especially dedicated to this task, because after one biochar smoothie, you won't want to use it for food any more. If you can poke some holes in the ground around your trees with a high pressure hose nozzle, then you can pour the the biochar slurry down the holes to get it incorporated into the tree's root zone.

Biochar, besides acting as a magnet for soil bacteria and fungi, will also buffer soil pH. It has many binding sites that can tie up soil alkalinity, making the soil more hospitable for your plant.

Thank you all so much! This is really great information. It's in the Pacific Palisades.

No need to worry about the alkaline soil. I have grown citrus in limestone and they turned out wonderful

Even better! Thank you!