Most likely not, European normally don't pollinate Asian plums, [toka & black ice/hybrid]. You should be fine with the two you've got. [ I think you mean good pollinator for black ice and toka?]

I knew my language would cause confusion there, haha. No, I am wondering if I need anything else to pollinate the mirabelle. The black ice and toka are a good pair with good fruit, But I don't know if either of them will make babies with a Mirabelle. Or if I need to plant a fourth tree to make fruit on mirabelles happen.

I do have a bunch of sand cherries around. I wonder if those would work? Someone keeps telling me sand cherries pollinate tons of plums...

Mirabelle is self fruitful...and yes, another domestica/European can increase production but might not be needed.

Sand cherries can help on the asian/hybrid plums.

Oh! Man, the plum language is confusing. As I understood it, japanese plums did not grow in zone 5a, which is where I am. i thought the black ice and toka *were* European plums. Are you saying they are actually Japanese hybrid plums? And are you saying my toka Probably isn't what's fertilizing my black ice? The sand cherries are probably doing it already? (All bloom prolifically around the same time.)

Finally, do you think if I planted something like a greengage, that would help the mirabelle along?

Black Ice and Toka are complex hybrids with Japanese, [Black Ice has some cherry] and have no resemblance with European. They should pollinate each other. Greengage might help in production but I don't think needed since Mirabelle is self fruitful, in my experience.

What would you plant, if you were a zone 5a plum grower? You're quite the expert so I just want to get you talking. :)

Hard to say...everywhere growing conditions are different and one should try a few and try out...ax the ones which don't perform or graft over. Green Gage is still a top notch cultivar but can't handle too humid conditions but I found out this year with lots of rain that it wasn't too bad compared to other prunus domestica/European.

From today, Green Gage...been picking for the last two weeks..this one can heal in some of the hail damage.

Prunus Domestica Krieche...

Not so good in healing in hail damage, most rot and aborted.

Wow. I sense there are more pictures up your sleeve re plums. I've seen a few in other threads...anything to share?

The perfect thread :) so you don't festoon anything, huh. I was going to festoon mine for ease of harvest. Black ice is 7 ft tall (can't guess age) but I can reach the tallest branches pretty easily...

What do you mean by >>festoon<< free stone? if so, sure, take pits out when processing for freezing or dehydrating.

By festooning I meant, anchoring the longest branches to the ground for a season. Then removing the anchors and permitting the branches to grow in their new, permanently bent position. The new weeping shape permits easier harvest because the fruit is lower...I'm guessing you do not do this? I admit I am relieved because I was about to attempt it and the process appears frightening http://www.allotments4all.co.uk/smf/index.php?topic=16215.0

OK..no I don't, no need, our northerly climate don't allow to grow huge fruit trees.

That makes sense - I am fairly new to gardening overall and I have noticed none of my trees get as large as they are reported to do in warmer areas. I just bought my first property suitable for planting anything in 2013 and am beginning my orchard this and next year. My selections are:

Plums: black ice, toka, mirabelle

Cherries (sour): U of SK Romeo, Juliet, carmine jewel and cupid

cherries (sweet): Blackgold, van, Kristin

I have slightly alkaline soil ph = 7.1, but mainly it's a lot of well drained slope and the soil itself is black and not too clayey. I don't know if these approach ideal conditions for fruit but I plan to muddle through. Thank you for your advice!

Don't make the mistake I did by planting on lower ground, [better black soil and frost pocket]..the higher the better and clay is fine. Fruit trees don't like wet feet, hardening off better on higher ground which is important to get them through winter.