It's done routinely by both home and commercial growers alike. As with all cucurbits, they don't like MAJOR root disturbance (wouldn't tolerate bareroot transplanting), but are fine with minor root disturbance (such as losing the trailing roots coming out of the bottom of the cell pack). I start them either in cell packs or 4" pots, about 3 to 4 weeks before planting out. They grow so quickly that there is never a problem with the root ball not holding together. Make sure they (like all transplants) are properly hardenend off before transplanting, and be sure to water them and mist them several times a day the first few days to make sure the wind and sun don't do them in before they become fully acclimated to the weather.

The grow bags do have drainage holes at the bottom of the bag although I could put more holes in them if necessary. What I consider to be a lot of sun is sunshine from 9am until about 7pm perhaps not directly shining on these plants the whole time. For direct sunshine Id say they get about 3 hours afternoon sun shining straight on them. The growing medium is basically what come in the grow bags with no added nutrients. They are Levington grow bags and I couldnt imagine that is what is causing the problem because 1) I have more cucumber plants growing in exactly the same type of bag which are growing fine and 2) the pea plant that has the same problem\symptoms are growing in a pot filled with John Innes No. 2 . I am watering with tap water apart from when it rains obviously. Again if it was the water that was cauing the problem I would think a lot more plants would be affected. They wree planted outside about 2 weeks ago just after been hardened off for a week because they were grown from seed. I am located in southern England. I dont know if this would have anything to do with it but these plants are situated near the rubbish bin store which can attract a lot of flies at times.

Cucumber and zucchini plants tend to get diseased after a few weeks of production, no matter what you do. Both are susceptible to mildew, cucumbers will get bacterial wilt from cucumber beetles, zucchini can get attacked by vine borers. You can check the base of your zucchini plants for holes and an orange frass. Dig inside and you'll find the larvae. I succession plant every 2-3 weeks and when the plants look bad i tear them out. You may want to try a fungicide on your plants, especially in the type of wet weather you're dealing with. Liquid copper or Serenade, or some have had luck with homemade fungicides made from baking soda or milk. It won't cure the disease, but will help protect any new growth. If it's bacterial wilt, there's no cure for that. Infected vines will die. It's very common with cucumbers; one bite from a cucumber beetle is all it takes.

This was cross-posted in the FL gardening forum, so I am presuming you live here, somewhere? FWIW, this is just the beginning of vegetable gardening season in much of the state. It's been way too hot, humid and buggy to grow much of anything. Some fruiting veggies like tomatoes cannot set fruit when temperatures are too high. They will still bloom, but no fruits will develop. Also, cucumbers are not always self pollinating, and even when they are, they have separate male & female flowers, so if there are female flowers(tiny fruits at the base) but no males(no tiny fruit at the base) pollination cannot occur. Looks to me like caterpillar damage is destroying your plants, as well. If you examine the undersides of the leaves, you might find tiny bright green caterpillars that blend in, along the ribs of the leaves. IMPE, it's often not worth the trouble, effort and expense to try to fight the bugs at this point, since the plants may already be so weakened they will never do much better. You might consider starting over. Here's a link to the University of FL's veggie gardening handbook, with recommended planting dates for our different zones: edis.ifas.ufl.edu/vh021