The soil doesn't look to deep. I think tongs with small grabbers and something like a long wooden spoon. The spoon could be used to loosen the soil around/underneath the plants nearest that hole before they are tonged out. Then it could be used to slide the whole mass of rocks and soil from the neck end toward the hole and work them out as they come into position. Hopefully, the one on the far right will slide to be more in front of the hole when others are out of the way. They went in, so they can come out. A long piece of bamboo might work in lieu of the spoon. I just like the idea of the spoon end and I use one here to cook with that's very small on the on the spoon end; others I have would be too wide I think. Alternatively, if worse comes to worst, you might try shaking them out (as gently as possible) like pennies from a piggy bank. All the above is assuming you don't want to bust the glass to extract the plants.
