Garden Bed Planning

I'm new to Permies, and have spent copious time reading about garden beds as I would love to fit some into the 3/4 acre yard my husband and I purchased about a year ago in the Pacific Northwest. We have five 100+ ft sequoia redwoods on our land that limit usability. For gardening, the easiest thing would be to take them out, but they are lovely year round, and on a property with a very high water table they help control minor localized flooding throughout our wet fall/winter/spring season(s).

That being said I'm trying to decide on the best garden beds considering these parameters:

1) The redwoods stay - with the exception of one that looks pretty unhealthy compared to the rest
2) I don't know how much digging I can get away with without seriously disturbing the redwood root systems. (I should also mention we have recently had 6 western red cedar get infested with beetles and are dying and being removed. I am not sure if the trees were dying and the beetles came in after, or if they beetles caused the dying. Regardless I am somewhat concerned about the health of the sequoias and would like to limit root disturbance if it might compromise them.)
3) I would love to try some hugelkultur but am not sure about the digging part due to the trees.
4) I have read that raised beds are not water efficient, but would that matter if we can easily dig wells just about anywhere in our yard? (Our water table is about 18" during the wet season, but I haven't measured it during our short summers.)
5) We have a lot of voles in our area that have decimated garden areas at our previous residence, so some kind of mesh or cloth to keep them out is a must.
6) My experience gardening near very large, water loving trees is they will root into any great soil and take it over - what is the best method of keeping my garden for food and not redwoods?

I'm leaning towards raised beds, but I also don't know how deep to make them if I decide not to dig at all. And can I still do hugelkultur if I don't do any digging? Or would that require my beds be way too tall?

Any experience with difficult gardening areas would be greatly appreciated!

Hi Kira, I have a garden built right next to a handful of redwoods (although they are only maybe 30 or 40 ft tall, i think they've been topped) and it incorporates some hugel elements. As far as encroachment, I give the redwoods about 10 or 12 feet of space and haven't seen any shoots come up anywhere near that far from the trees nor have I encountered any of their roots in the limited digging I have done there.  They form the eastern border of my yard so their biggest contribution is shade that persists most of the morning even in the heart of summer.  As far as the hugel goes, mine started as little 2-3 foot tall mounds, I did remove strips of sod to set them into but there wasn't any real digging, they have since shrunk to about a foot above the surrounding garden area. I don't see any reason why small hugels can't be a thing, they just won't be as long lasting as large ones or create the same level of microclimates, but they will still have microbeasty habitat galore and get you a raised and sloped garden area. I have also seen no worse vole/mole/gopher activity in/around my hugels than in the rest of the yard.

Sorry to hear about the borers finding your redwoods.

Good raised beds work best if they are at least 16" deep.
Voles can be deterred by using raised beds of 18" to 29" tall  (a good bench height) and sinking either the base of the bed surround material or heavy gauge 1/4" hardware cloth sunk around the perimeter.
Hugels can be built above ground, almost all of the originals were stacked, rotting wood that was covered with soil, they can be just about any height you want to make.
My hugels are around 3 feet tall, the big thing with hugels is to use well rotting wood instead of fresh cut wood.
In Europe it seems the hugels started out as fire wood stacks that weren't used and started to rot, at which point soil was thrown over the wood then plants started growing on them and the locals noticed this and made use of them for food plants.

Instead of digging I would go to the trouble of adding soil as I could.
First thing to do is map your sunlight travel so you know where the most sun is and I would also map where different amounts of shade are located.
That will help in planting planning so each group of plants gets the sun they need, or as close to their needs as possible.

Redhawk