We planted Vroma fava (a culinary, big-seeded variety) around our trees about six years ago, and they have multiplied each year. This time of year in our 10a California area (SF bay; east hills), we have a sea of blooming favas in our small orchard, growing thick enough to suppress weeds. They help break up the heavy clay soil and maybe provide a little nitrogen. We also get an excellent crop of fava beans annually, with very little effort. Some years I have “helped” them reseed (pushed some seeds into the ground here and there when I noticed them lying out), others not.
Favas were a favorite cover crop for Luther Burbank, who did his work not far from here. It really does seem to work in our conditions.
I will note that I have noticed that they turn black and shrivel in the fall. It occurred to me for the first time this past season that perhaps they could be introducing spores if I don’t chop them down at the end of their growth. I don’t actually know that this is from disease and may very well just be the way they look when they croak. And even if there are spores being introduced via fava, it’s unclear if this might be a threat to fruit trees.
This year I’m trying daikon (Groundhog) for the first time, as well as a dwarf fava (Robin Hood). The ship may have already sailed, but if I could do it again, I may have chosen a shorter fava to introduce. Some of the youngest, smallest trees can get a little shaded by taller favas.
That was my concern before I started using plastic sheeting, but, because it is used on crops, I figured it didn’t block the water. I note that water does collect on it, but I puncture it to let the puddles drain. Also, I apply drip irrigation under it, and, after all, moisture does seep in from the edges. The irrometers I’ve deployed show soil moisture waxing and waning underneath. The trees don’t seem to suffer. I’m pulling up all the plastic sheeting because it’s difficult to maintain, not because it wasn’t effective at preventing undergrowth.
It most certainly IS A THING! I was taught (without my questioning the concepts): A. To keep the graft union above the soil. Also, I was taught: B. To keep the graft union as close to the soil as possible.
If you don’t A, then the scion may grow its own roots, and you loose the desirable dwarfing character of the root stock. This is not to say that many growers will transplant nursery stock, burying the graft union to produce full-sized trees. I suppose many growers will manage tree size by pruning. I prune, but I rely on dwarfing root stocks to limit the ultimate vigor of my trees — hence my desire to keep the graft union clear of the soil.
I’ve never been really sure of the need for B. I’ve always assumed that the graft union would be stronger or less prone to wind twisting if it were closer to the ground. (All my dwarf trees are permanently staked, anyway.) Suffice it to say, however, that I was provided explicit instructions to transplant whips, feathered trees, and bench grafts deeply so the graft union was no more than five inches above the soil line. I now note that many growers will graft and transplant trees so that the graft union is at least ten inches above the soil line to allow for the build-up of mulch, but this is counter to my training (such as it is). Perhaps planting deeper affords some flexibility in the layout of the orchard. If you lose a bunch of trees to either side, it’s a simple thing to turn the survivor into a full-sized tree just by hilling it up.
JCutts, if you’re reading this edition you’ve no doubt seen the stories about rabbits and other rodents damaging fruit trees in our orchards. Putting down a thick layer of pine bark mulch in close proximity to your trees will help the retention of water and the propagation of soil friendly fungi. Just avoid mulching any closer than 2-3 feet to your trees. The ground covers offer voles an excellent hiding place. So that business about castor oil mixed with peppermint Castile soap sprayed close to and on the trunks of your trees might help keep deer and rodents away. A sharp hoe will help keep the weeds away from the base of your trees too. I hope that helps.
I do cardboard a few inches away from trunk covered in wood chip pretty deep. as it degrades I’ve been planting my garlic, chives, and walking onions into it. right up to the trees almost, on the bigger guys.
I have a lot of that field mallow and some clover that comes up among it all and that’s been ok too. I try to keep things back from the smaller trees’ trunks though.
I usually seed in winecap into the wood chip areas, especially if I’m topping off an older area where the cardboard is broken down and I can dig under to get the spawn right up against soil then cover with the chips
now this is all in the cooler areas of my place. I’m high desert so summer is dry from June-October and hot up 110F+ at least two weeks of that. so the sunny areas I tend to just mulch like hell from the drip line on in to a foot from the trunk. that foot on young trees is the only place I do real intensive weeding in the entire garden.
I grow the bocking #4 non-invasive type, and keep it below most of my trees. If it’s gets a little bigger than I prefer I just chop it down a few inches from the ground and spread the leaves for mulch.
Weed barrier fabric attracts rodents! A LOT! Also, over time, the soil under it (at least clay soils) gets more compacted, and grows a bacterial slime. I think the bacteria inhibit mycorrhizae.
I would mimic the forest and use leaves, decaying dead wood, and wood hips or mulch.
I initially place a hemp mat if the tree is small, followed by wood mulch later in the season. Outside of the mulch ring, I interplant fescue or a low lying clover, such as dutch.
If it isn’t a rowed series of trees, and more naturalized looking, I plant smaller perennial herbs and flowers near the drip line, and usually other fruiting trees and shrubs to separate species that can share multiple disease; alternating species.
I have guys that mow my orchard during the summer only 22 trees. They are super destructive, but I love them. if you ever need an extra layer of protection, this border that I buy from Lowes and just hold together with a couple of wood screws works really well. Might need to put a couple of anchors on it or pile a little dirt on the inside every spring, I just replaced what I need when they cut it
