Is blanch freezing vegetables required for short term storage?
Blanching is done to halt enzymatic action that would start to destroy the plant cells. You can freeze without blanching and the veggies will still be edible even after 6 months but their quality will decline faster.

If you are planning on juicing those veggies within a month then you are going to be doing a lot more damage than the freezer will and I don't think you would see much benefit from blanching. The spinach and celery might stay a little greener when it thaws- the carrots and zucchini would probably not be effected at all.

As for the sugar water. Are you planning on freezing them in the water? I don't think that would do much but dilute their juices when the ice crystals rip them apart. Of course you wouldn't be able to keep spinach in a bowl of water for a month- that would be more like a swamp than food.