Material like this is likely to be quite slow to compost. As for needing to pour on organic material year after year, the optimum amount is actually not that high. Depending on how much you started with and how much you have added, you may be to a point where you can cruise for a bit. Or have even overdone it.

https://puyallup.wsu.edu/wp-content/uploads/sites/403/2015/03/soil-amendments-3.pdf

You can certainly use the needles as mulch, however, and they will do a fine job of it.

The needles from those redwoods could be a good addition to the soil as a mulch, as long as they do not raise the amount of organic matter above the optimal 6 to 8 percent level. It takes about 10 tons of organic material per acre to raise the level of organic matter in soil about 1 percent.

However, if the needles are in the forest and on land that is not yours removing them to your garden would probably be illegal and not very environmentally sound.

kimmq is kimmsr

I agree, they will make great mulch. If you have grass clippings mix them in as well since that will help break them down over the winter and spring. Also, don't be put off by the fact that they may be slow to compost. Nothing wrong with slow.

"I've been thinking about this for several years but assumed the redwood
needles were not good for the soil since nothing seems to grow very well
underneath the trees, just realized that might be due to lack of light."

It's VERY GOOD for the redwood trees to have mulch from their needles and little competition for nutrients and water.

If the trees are not growing on your property, leave them alone.

lazy_gardens the trees are growing on both sides of a creek, about 6 trees, and dropping some needles on my side of the fence. My plan is to collect the needles from my side. In any case, my garden is so dinky I just need a garbage bag full and will leave the rest. That is just a teeny tiny amount compared to what they drop especially on the other side of the fence where the actual trees are. A few years ago that property was renovated and the owners installed a pretty stone patio all around the trees. Hopefully they get enough of what they need from the creek and the few fallen needles that are left after a team of "blow and go" landscapers swoop in and bag all the needles from the other side. Not an exaggeration....

I would argue that the reason not much grows under your trees is it is harder for plants to compete for sunlight and nutrients with established trees.

Lol... yes I agree with sylvia. In fact, having them all collect in Texas wouldn't be good either, they need to be spread out as far and wide as possible. I shall selflessly sacrifice the ground under a few blueberry bushes.

Thanks everyone... good to know they are okay to use. I remember reading something negative about using redwood in hugelkultur or however it is spelled.

The wood itself is extremely rot resistant which is not a good recipe for hugel. The needles are not necessarily the same although I know nothing about composting them. If they're like most pine needles they are probably a bit slow.

First of all, there are things that do quite well under a redwood tree. I have a 15 year old

Camelia under my redwood which provides it with shade at the hottest part of the day. It is slow growing, but very healthy with beautiful pick flowers. I never water it. It thrives in 6 to 8 inches of dry fronds.

By the way, if you have a redwood, never remove the fronds from under the trees because about one foot down is the most beautiful natural compost you have ever seen. That compost is surrounded by small redwood feeding roots.

I have Solvita tested it with excellent results indicating compost maturity and vitality. As far as the fronds that are blown out from the tree, I compost them with great success. I use the ucanr Berkeley method for accelerated composting. I have a finished batch right now that I will use under my fruit trees. Since decaying fronds are fungi dominated, they are more suitable for trees. However, that does not preclude their use in the garden.

Yes, they do take longer to decompose, and you will still be able to see the broken down fronds.

Make no mistake, these fronds are mature and ready for use. And they provide air space for you soil. What could more ideal. Those remnants of fronds will provide all the needed air space that you plants or trees need to flourish.

It took me 40 days using accelerated composting to produce a finished compost. The ucanr Berkely Method involves turning the compost after 4 days, followed by turning every 2 days until the compost is mature. Temperature should be maintained between 110 and 160 degrees F. I used a mix by volume of 60% fronds, 20% garden greens and 20% steer manure max

That is because it takes more Nitrogen (green garden material and manure to break down the fronds.

If you choose not to use the Berkeley Method, and wait longer between turns, it will just take longer, but not forever.

Good luck and happy gardening.

Bob

Master Gardener, ucanr

I have always wondered about this. We have lots of redwoods on the property and the fronds need to be cleared from paved areas -- patio, steps, roofs, etc. -- or they will be three inches thick at the end of the rainy season. When I do rake and clear, even after a few months, the top fronds are visible, but underneath is the richest, blackest soil. Looks like what you get when you buy garden top soil. Is the color an indication of the chemical composition?

Or moisture?

I have a very large Dawn Redwood in my front yard. I have numerous hostas underneath and they flourish. The needles fall onto my neighbors yard. I remove most of them from his grass because they accumulate too much but many work their way down into the soil. He comments that this area of his yard has the absolute best grass.