i've read about it, i think over in the square foot gardening forums. but never tried it.

Im currently doing that with a couple of Peach trees but not Citrus. I think it all depends on pruning. Do not let one tree over take the other and shade it out and you should be fine. Give them enough food :-)

There are some factors in how well the pair does that aren't apparent at first thought. The big one is what rootstock(s) are both of the trees on? Different rootsocks impart different performance to trees. Cara cara and trovita (the above ground portion of the trees) potentially grow with about the same vigor, that leaves the rootstock as a potential big difference.

So just from a balanced performance standpoint, you want the trees to be on the same type of rootstock ideally. Going past the differing performance of different rootstocks is an interesting aspect. Tree roots apparently have the ability to recognize if they are related to other roots they encounter underground. If they are genetically related, they will tend to give each other leeway. If they are unrelated they will tend to compete. The battle for supremacy isn't just above ground, it also happens underground for closely situated trees. The trees will get along together much better if they are on the same type rootstock. Trees on different rootstocks will be a constant pain because there isn't a good way to balance differential root growth by pruning like you can for the above ground portion.

Most likely, being in California, your trees are on Carrizo, or C-35 roots if they are full sized trees. If they are dwarf, they probably are on flying dragon unless they come from Four Winds. Four Winds uses cuban shaddock as their dwarf rootstock. Carrizo and C-35 won't compete or out perform each other too badly. A pairing with or between the other rootstocks is going to have more issues.

If you have a little time and interest, grafting is an easy technique that is very useful for a space limited gardener that wants more varieties. Youtube has quite a few videos showing how to graft and explaining the differences between techniques. It is easy to get good results if you pay attention to the calendar and don't push the seasons. The techniques used on stone fruit varieties and apples are very much the same as those used on citrus, so videos of grafting those trees are applicable to citrus (although the trees themselves are in no way compatible).

Tim, I love the look. I hope it works out well for you. Your trees are just beautiful. Keep up the good work

Mike:-)

Thanks for your comments, guys. I really appreciate it!

@houstontexas: I perused the site and it seemed mostly about high-density planting of vegetables, which I hadn't thought about before, either...

@blazeofglory: Hey, blaze. Yes, I had heard about doing it for fruit trees and this is what got me going. Did you get the idea from Dave Wilson Nursery in Nebraska? [link attached] Unfortunately, I only found them after I'd thought to put my citrus in the ground, LOL.

@bada_bing: I did think about grafting, but hadn't done it before (though may yet try!) I was thinking something more immediate & was also keen on doing the multi-planting thing and seeing what happens.

You bring up a really interesting point of rootstock compatibility(!), and one I'd only given very brief thought.

I bought the Trovita a year ago from Lowe's and figured that since it was labeled a 'dwarf' as was the 4W Cara Cara, they'd be compatible enough. Still not sure exactly what rootstock the Trovita is on (nothing on the Lowe's tag mentions this), but it probably is the Flying Dragon (orange) rootstock as opposed to 4W's Cuban Shaddock (lemon/lime). Do you happen to know which of the two is more aggressive (I'm thinking the Cuban Shaddock)? I may just leave in the ground to continue the experiment and see what happens (after all, Trovita may yet be on Shaddock?), but if the answer to the above is that Flying Dragon is more dominant, I might yet take out the Trovita and replace with a 4W tree. Thanks so much for your insightful comments!!!

@Mike: Hi Mike! How's it going? I promise to take some recent shots of my trees and add to your June photo post(!), especially as I've also just added a Bearss lime as well. This too is an experiment, as I'm seeing how it does indoors full-time (at the spot getting about 8 hrs direct light that I was able to previously flower plumaria). My potted IML is in the only spot outdoors that gets >10 hrs direct sunlight; however, it is also VERY windblown and seems to be hampering growth (you'll see on the photo). So, I'm trying the lime indoors...

Best,
Tim

Here is a link that might be useful: Multi-tree planting example.

I have done it. Like you I am running out of space or at leat good southern locations which are vital for Citrus. I read about it and saw a video on Youtube where some guy at an Australian nursery does it.

I am in Zone 7A so I am restricted to hardy varieties. I planted two Citrumelos in the same hole. Elsewhere I planted a Citrumelo and a Thomasville Cintrangequat in the same hole.

One year on, all 4 are fine.

Excellent, jacklord! I definitely saw the same video(!), although at the time I was thinking that there really was a whole lot of land around his demonstration planting area, LOL.

You wouldn't happen to have a picture of your plantings, would you? I (and I'm sure others here) would love to see your trees! To post photos here, you can place your pics in Photobucket, then copy the HTML that appears by hovering over the photo and paste this into the body of your message. When you hit 'Preview Message' you should see your photo(s).

Best,
Tim

Well, maybe if your trees are on true dwarfing rootstocks you can get away with this, Tim. Citrus are such high nitrogen demanders, I wonder if either tree will do very well. Not like stone fruits. Check with Tom Shea at the UC Riverside Extension Services. He might have some anecdotal experience, since he's out in the field in the S. California area, and may be able to share whether or not any other growers are attempting a "two in one hole" approach with citrus.

Patty S.

TimSF:
I have also double planted citrus trees, but not for lack of room but rather as an experiment for my cold climate.

The temps in winter here can get down to the low double digits (10-18F) so I am experimenting with two in a hole to see if they will act kind of symbiotically, where each only has to bear some of the cold winds, snow, etc.

Specifically I have two mandarin trees planted in my front yard I am doing this with. Also I am growing some Kumquats from seed and I have a pair that I have literally wrapped their trunks together. Once they get old enough I will plant these in the yard also.

A third thought is mixing species- An evergreen hardy bush of some kind with a citrus. The evergreen bush will help protect its neighboring citrus, of course the citrus would get less sun in the growing season, but I think it might be a good trade off if it allows marginally hardy citrus to grow here.

Aside from root competition or cooperation, it is important for this idea, as in cocktail (multi-graft) trees that the different varieties require the same sort of care... especially as to fertilizer. I would also try to lose the stake or tie it with a loose, non-restrictive tie if you are in a high wind area.

And lastly, I would add some dirt to cover those root flares; that is acceptable in container growing; but in ground it tends to attract roots diseases and critters who will chew them.

Any updates on these multi plant holes for citrus?

I have a pair of pear trees planted like that but they are 4 feet apart. I had 2 Bradford pear hybrid seeds grow there and I grafted ma Maxine pair to one and a Giant Turnbul to the other. I did not transplant either one so they will live as a pair.

6b Steve