Thanks for the report on the handle material. Let us know how it works for you.
@alan I’ve found that ash can last quite well if you remove the factory finish and treat it with linseed oil and finish with wax. I like a beeswax/mineral oil mixture. I bet a spar varnish would work OK too, but I love the feel of the linseed oil and wax finish.
I like linseed oil. I’ll try a little wax/mineral oil - have a couple of chunks of beeswax. Do you heat the mixture or just grate the wax and stir? What ratio do you like?
Thanks.
To be honest, I just have a tub of ready made stuff that I bought ages ago from a kitchen store. I think it’s 50-50. I think you’d have to melt the beeswax in. I made a similar mix once from linseed oil, parrafin, and pine tar to make waxed canvas; I bet that would work super on wooden tools. I did have to melt that all together. I re-apply periodically, and I also like to wipe it on the tool heads before I put them away for the winter, at least for hoes and axes.
Well, removing the finish would be like paying double for me. I routinely coat all my wooden tools with boiled linseed oil at least once a year, and it helps, but it doesn’t penetrate where metal covers the wood, and that’s where tools tend to break. The manufacturers finish does stop moisture from penetrating but it rapidly gets scratched and nicked and finally completely worked off the wood. My thinking is that as long as the linseed oil penetrates the scratches I’m good.
Fair enough. In all honesty, I certainly don’t do all my tool handles. I’m more likely to go out of my way to do it on striking tools like axes and hammers. Some are better than others, but I just don’t like the feel of varnish as much and I think it’s more likely to give me blisters while still being slippery. The wax finish is velvety smooth, gives me a solid grip, and it never cracks and peels into those sharp slivers. The best axes often come with this finish, or just linseed oil, so you get ahead of the game there.
On the subject of handles, I think the bigger issue is grain orientation rather than ash vs hickory. The grain should be running parallel to the direction force is applied, but with modern saw cut handles, it’s a crapshoot which way it’s going to run. It can make the difference between a handle lasting 50 years or 5 days. Again, the best tools usually have this covered (part of the price increase), but I prefer to pick my tools or replacement handles out in person for this reason.
my father used to have a 5 gal pailful of used engine oil that he would soak his tools in. they never rotted or broke. i still have some of his tools 5 years after he passed. you would think they were slippery but once they were out of the oil for a day they were perfect. never need to reapply. 
Everyone has talked about digging the holes. That isn’t all there is to it. Around here if you don’t enclose each tree in a protective fence you can kiss it good-bye. The deer will destroy it in a matter of days. I also put hardware cloth or at least a spiral twisty around the trunk tp protect from rabbits. Deer and rabbit spray, mousetraps help, too. I know ground squirrels and gophers are problems in California. I’ll let someone there address that issue. I just don’t want you to lose everything as soon as you get it in the ground after your hard work and expense of planting.
Thank you to all for the incredibly helpful advice. Not to mention the encouragement! The task was very daunting to us, tho it ended up being a-okay.
As several suggested, we invested in a good spade and a pick, and these two tools were really all that was needed, along with a basic trowel. Having a sharp-tipped spade was nice, tho a shovel could have done the job too, so I don’t think having both is absolutely necessary, as long as you have a pick.
Splitting up the work by digging holes ahead of time was an excellent suggestion. The ground was unusually dry this winter, which I understand can make digging more challenging. Watering first helped shovel more efficiently, but wasn’t strictly necessary for digging (tho we did water before planting anyways, for the tree’s sake). Each hole only took about 30 minutes to dig at most, tho I stretched it out to an hour with lots of breaks. I was concerned I’d get a repetitive stress injury since digging is new to me. With breaks, there was no issue.
The hardest part was dealing with some redwood roots that were still in the ground from a tree that’s no longer with us, but hacking away at it with the other end of the pick was mostly enough. I could see how an ax would have helped tho—a couple holes were relocated to avoid old root I couldn’t quite tackle.
We also lined most holes with a double layer of chicken wire, as we live in Gopher City. We didn’t line the holes of our 6 kiwis, and we have already lost two to gophers. Skipping that step is not recommended if you have burrowing critters around! They do seem to be letting the berries be tho 
Won’t be skipping this step again.
To be fair, the digging was quite physical and taxing, so I don’t want to give the impression that it was a breeze. If you have good technique and lots of practice, I’m sure one could do all the work we had in a single day. For those of us maybe not used to this particular task, i think breaking up the work by digging ahead of time is a great idea!
Thank you to all of you for the help! 
Sounds like you did a great job!
Here’s a tip for the future. You can buy small cordless reciprocating saws that are great for dealing with buried roots. Much less effort than an ax, and they can also be used for pruning. I used to have only very basic tools, but I am just one person with a seemingly unlimited amount of gardening work, and I need every timesaver I can get. So now I buy any tool that I think might be useful. There have been a few that have turned out to be duds, but the majority of them get used more than I thought they would.
That and a 3-pack of pruning blades for ~$12 at a big box store. I abuse one of 'em for cutting roots like that and still have 2 for regular pruning duties.