Posted: 05/05/2015 at 07:23
Rain won't hurt them beyond wetting the foliage. Aim for air circulation as a means of helping against fungal problems.
Plenty of room between the plants, and as they grow upwards, nip off the lower branches and foliage to keep 12-18" of clear space between the lowest foliage and the mix. Fungal spores will turn up, there's no escaping them, and they can and will drop from the foliage down onto the mix. Watering can splash them back up again. The clear space helps against this.
And don't be afraid to thin out foliage across the plant. Judiciously, obviously, you don't want to denude the thing, but you want to be able to see light through all the foliage. Impenetrable clumps of foliage work against air circulation and are heaven for fungal spores.