I managed to get over 100 Zen Eggs in less than 24 hours. The 146 seed packs were all from today.

As I'm nice, I shall share the method which I had read about on reddit I think.

Buy a BUNCH of Zen Flares. They work best since they grow the fastest and are easy to get. Plant them all down around a single area.

Wait for them to be ready to be harvested, which will be quite a lot. Once ready, place all the Komadas you can (since they have a chance to turn a harvested zen type crop into tranquil). Using a team of 8 Komadas can get you a minimum of 50% chance for each harvested crop.

Once you have harvested the zen flares, go down to the zen channeler and give him all your fruit. Hopefully, you should manage to reach 325 Zen each time which will grant you multiple rewards. Just do this on repeat and keep getting more Zen Flares.

I also use Sakura bushes since they give more zen than Zen flares so I recommend that as well.

Reached 70 Zen Seed Packs, it's taking ages so I'm going to stop there for now. Best I got was two Hinomais.

Hope my eggs grant better luck!