Hello! I have a small suburban lot in the San Francisco Bay Area. I have my dwarf fruit trees ready to plant into my Zone 3. Any suggestions for understory nitrogen-fixers? I really don't have room for cropping Acacia trees. Thanks!

Lupins? Flowers much loved by bees.

Or if you want something really low, clover or birdsfoot trefoil?

You can also keep some N-fixing trees to a shrub size with pruning, I have shrub sized elaeagnus

I'm also working with a suburban lot. I tend to try and squeeze in plants that either have flowers or are edible. I like my elaeagnus bushs in my front yard. In late winter/early spring they're covered with small, delicious berries. Goumi are in the same family and also fix nitrogen. I'm growing false indigo below my espaliered peach trees.

If you're willing to plant each season, there are a lot of productive bush forms of beans. They'll not fix as much nitrogen as if you were tilling under before beans form but would provided another option.

TO: Chris Ferguson
FROM: Eric Koperek = erickoperek@gmail.com
SUBJECT: Ground Covers for Dwarf Fruit Trees
DATE: PM 7:47 Monday 23 May 2016
TEXT:

1. Seed Dutch White Clover = trifolium repens at 12 pounds per acre. Dutch White Clover grows only 6 to 8 inches high so you never have to mow it. Dutch White Clover grows vigorously = it is highly competitive = it blots out most weeds. Dutch White Clover also tolerates shade and field traffic so it is a highly persistent living mulch. Remember to inoculate clover seed with nitrogen-fixing bacteria before planting. Dutch White Clover is often used as a ground cover in commercial orchards. Other low-growing clovers include: Crimson Clover = Trifolium incarnatum and Sub Clover = Trifolium subterraneum.

ERIC KOPEREK = erickoperek@gmail.com

Thanks for your responses. I will try the clover and beans. Casie, do you till the false indigo into the soil? I did try Palestine Clover under my trees in Las Vegas area but they were too thick to easily till into the soil.

False indigo is a perennial, no tilling. I wouldn't be inclined to do any tilling in the root zone of a tree (why I mentioned that you would have reduced benefits from annual legumes)

With the clover and the beans what you probably need to do is actually chop and drop. When you cut the top, the corresponding root die back releases nitrogen into the surrounding soil. Your tree roots are also growing there, ready to immediately access this resource. No tilling required, in fact you benefit from minimal root disturbance all around.

With perennial plants you have the added benefit that the still living plant will regrow and capture more nitrogen to repeat the cycle with in the future. With annuals you have to replant to repeat.

Sorry- San Fransisco/Bay Area- Zone 3?

If you are in the bay area and zone 3, you must have a snow machine or defunked icemaking business. I'm guessing you're really zone 7. See: http://www.sfgate.com/business/article/USDA-releases-new-Plant-Hardiness-Zone-Map-2699544.php#photo-2170804 for a map.

Looks like most of the suggestions so far are appropriate for the bay area though. There are also perennial pea vines I would check out, as well as some clovers. the pea vines are often edible, or part of the plant is edible (hyacinth, runner beans) but clovers are usually not. Your season might be long enough for peanut. There's also apios (potato bean), but that one you have to disturb root area for, unless you just focus on the pods. Dry beans may also work or chickpeas (which used to be grown not far from there as an ag-crop)

Good luck!

Amit Enventres wrote:Sorry- San Fransisco/Bay Area- Zone 3?

Must be permaculture zone, rather than USDA Zone.

Thank you Amit and Seva: Whoops, I meant Permaculture planting Zone 3, i.e., Zone 1: out the kitchen door, Zone 2: close in the yard, Zone 3: fruit trees out in the back, right? Suburban lot doesn't allow for outer Zones. Our "back forty" is "back ten" - feet not acres. : ( I like the pea idea. And we are USDA Hardiness Zone 9b. USDA says 5b - 10b for peanuts. So I think I could grow them. Sorry for my inexperience - don't we cut the plant to have the nitrogen nodules fall off the root zone in the soil.? Would I then cut the peanuts before I could harvest them? I'm new at posting so I'll be sure to be more clear. Thanks again for great advice.

Oh, I see. Casie, I was confusing chop and drop with tilling into the top inches. So when we chop and drop, then the nitrogen nodules drop off. Okay. I'm off to the plant store. Thanks again.

Chris! I was just about to post a bit from Dave Jacke about fruit tree polyculture and ground planting when I saw this. You should definitely come to the Forest Garden Design Intensive course this June!! It's in Nor Cal at Heartwood Institute. We have scholarships available and with this style of course you will get to ask questions specific to your lot, climate, etc. We would love to have you here and to know more about what you are doing!
Also, stay tuned cus i'm about to post that poly culture thing
Best,
Ellen

Course Link
Heartwood

Ah! Chris- that makes more sense Permaculture zone - lol. Good luck with the plants. I'm no expert on root nodules, but I think the science isn't perfect on them. I believe that when you grow an N-fixing plant, no matter what you will get some additional N in the soil. If you chop and drop the top of the plant, what you drop is going to add N to the soil. Some say the nodules will fall off and add more N to the soil too. I'm susupicious of that- I would think the plant would just use them to make more leaves. Some studies show plants and soil buggies share nutrients, so there's another possibility.

Amit Enventres wrote:Ah! Chris- that makes more sense Permaculture zone - lol. Good luck with the plants. I'm no expert on root nodules, but I think the science isn't perfect on them. I believe that when you grow an N-fixing plant, no matter what you will get some additional N in the soil. If you chop and drop the top of the plant, what you drop is going to add N to the soil. Some say the nodules will fall off and add more N to the soil too. I'm susupicious of that- I would think the plant would just use them to make more leaves. Some studies show plants and soil buggies share nutrients, so there's another possibility.

My understanding is that when you chop the top of the plant, you have root die-off and those root nodules die too and add N to the soil. The roots that are still alive contribute to the plant growing back and growing new leaves, as you said.

Todd Parr? The author - one and the same?

Chris Ferguson wrote:Todd Parr? The author - one and the same?

Unfortunately, no

I've tried lupines, dutch clover, crimson clover, favas, seaberry, and autumn olive. As far as nitrogen fixing goes, I'm not sure what has been the most successful. The lupines are certainly the easiest and prettiest once established. I've been helping them seed new plants by taking the seed pods and sprinkling the seeds around in the spring. That has been successful. I had to replant the dutch clover this year, but I think the crimson clover will reseed. I plant favas every year both for the beans as well as a chop-and-drop mulch once the seeds are harvested. People will say you need to chop them before they go to seed, but it seems to have been working out pretty well so far. I put in six new fruit trees this year and planted a seaberry or autumn olive right next to the roots along with a comfrey plant. My plan is to cut them out once the trees are established, particularly before the autumn olive gets too big. The seaberry might get to stay. It's all actually a lot simpler that you think at first. Just get some nitrogen fixers in the soil and let them do their work.

I don't think they add nitrogen back into the soil, but my strawberry plants love it under my dwarf apple trees.

I am not familiar with all the nitrogen fixers recommended here. But I have Dutch white clover under my apple trees. Another advantage of this is the clover blooms throughout the summer and keeps the bees fed. So I have a healthy population of pollinators in the area when my trees bloom. There are probably other plants that continue to bloom.

Also innoculating the area with mycorrhiza can help your fruit trees access that nitrogen in the soil.