I planted a xeriscape garden last year & put "yum yum" mix (from High Country Gardens) in the bottom of each hole. I plan to fertilize again this fall. I'm hoping to get some guidelines, here, for fertilizers - ie. what #'s or ingredients should I look for. Should I add worm castings, alfalfa, etc.? Any suggestions are welcome. I'm planning to fertilize each fall & add compost each spring, going forward - does that make sense?
Yum-yum mix is good. I've had my best success with mineral additions to my soil to boost the elements where it was low and adding minimal amounts of organic matter at the surface. (This is basically what yum-yum mix is). I'd recommend you get a soil test done so that you know what minerals you do and don't have. Look at the yum-yum and consider other products to make sure you are adding enough of what you are short in. I would also recommend a mycorrhizal fungi addition as the fungi will help feed the plants. For Fall/Spring additions, all I do is add them at the soil surface, scratching the top 1/4 inch or so of the soil. I use more minerals in the Fall and more organic matter (compost) in the Spring.
Your Xeriscape plants won't all prefer the exact same kind of soil and amendments. I'm not familiar with your climate zone, but as a generalization: if it is a very LOW water plant, it probably needs needs the crown protected from excess moisture. So avoid organic mulch, peat, compost, alfalfa pellets, etc, around the crown where they would tend to hold water.
Thanks pollengarden. My goal in planting a xeriscape garden is reducing water needs. We have been experiencing drought conditions for a few years now & I don't anticipate that changing long-term. Thanks for the reminder to keep amendments away from the crown of the plants.
My gardening background is extensive and researched CA natives and dry plantings, they don't want fertilizer, you'll kill them with kindness or encourage pathogens. Compost has too many nutrients, the plants will grow fast and die early. find an acceptable wood type mulch that is aged and lay it on thick between plants, it will settle over winter. It has a bit of nitrogen so it won't rob the plants, that's when leaves turn yellow with a few green veins.
Our area doesn't have thick rich leaf matter like back east where I grew up. Mediterranean climates are dry, rocky shallow soils and well draining for the most part. Mulch conserves water and the worms will surface and slowly mix the organic and mineral with their castings and fertilize plus aerate.
I have read books on this and it's better to go slow, let the plants get their roots out naturally. The rule with natives is first year they sleep (getting roots out). 2nd year they creep, 3rd they leap. Always find the mature size height and width, plant accordingly over planting I found is a mistake. I always look for smaller varieties because they mature nicely and don't need as much maintenance.
Well, that's more than two bits of advice for one night
Absolutely untrue that CA natives do not want fertilizer. Maybe not as much as your average tomato plant (like an order of magnitude less) but they will definitely respond to fertilizer and be more robust and drought tolerant when they are not growing in nutrient-deficient soil.
The best way to ensure they have access to nutrients is to put some compost in the mix when you plant them (you can mix in some pumice or lava rock if you are concerned about drainage). Be sure to mix it well with the native soil, so there's not a bubble of potting soil or compost around the plant once it's in the ground. That way it will root outward into the native soil. Mulch every so often and you should not need to concern yourself with fertilizer. But otherwise, if you have nutrient poor soil like we do here, you'll find dilute fertilizer can improve the health of your plants.
Native plants prefer their native soil, which you probably don't have in your yard. Most yards have at best disturbed soil from the construction of the house, and at worst no soil from the original re-contouring to build the development. In their native environment, they form colonies based on the conditions at that specific site. Fortunately, most tolerate a range of conditions - if they grow anywhere in your region, they can probably adapt to the conditions in your yard.
Get a soil test done, and correct any problems. Do not treat blindly for a problem you may not have. I was sure my own yard was very alkaline, and I had a test done to find out how bad it was. It turned out it wasn't that alkaline, but it was high in salts, and low in phosphate (unusual in Colorado).
Then zone to create your own colonies based on sun/shade, soil, and water requirements. Plants that take more water should have more organic matter in the soil to retain more water. Plants that hate water should have better drainage and not be in a low spot. Plants that are borderline for your location may need a more sheltered spot.
You might want to try a plant in more than one location - then if one fails, you will have a better idea if it is the plant, or the location. Some native plants are tricky, and it is a much a matter of luck as anything.
Along those lines, try growing plants with or without mulch/amendments/whatever, side by side, so you have an idea of how your changes are specifically affecting the plants. In the end, like pollengarden says, it really depends on the soil where you are. It's often a mistake to make sweeping changes without tinkering a bit to see how you're affecting the outcome.
Another thing. Rain water is much better for plants in the ground than the really alkaline well water we have here. You will likely find your plants establish quicker with rain water, and if they are natives you will see a dramatic change in how they look during our rainy season (mostly winter). Bear that in mind when you assess the situation. The past two years have been very dry here and some plants have been very slow to get started.
The best success I had was Manz Dr Hurd with a clay soil in LA I didn't amend it but it was in an area we had to do some trenching and backfill. after 5 years it's chest high. I had 2 Ceanothus Centennial on top of the 2'brick wall with back fill, they exploded because of the loose soil, some compost but mainly on the surface. One has since died but the other is taking over that area.
I planted a third plant other side of yard with little digging in hard clay and it's low, flat and uninspired to do much more. I think it was breaking up the soil and getting the roots down for best growth. I leave leaf trash to decompose and create it's own mulch.
The Arbutus Compacta grow 8" every time they get water. Not native but wonderful at 7' and keep them hand pruned. Gophers came into the yard from construction nearby 4 years ago and ravaged some plants so I'm going to replant with "toxic" plants. Wiki search turns up an amazing amount of poisonous plants.
When I was at a Native nursery they told me no fertilized compost but inorganic additions to aerate the clay. Can't remember the name but it wasn't builders sand. That will create concrete conditions with clay.