The 'click in ' baskets I bought this year already have water reservoir space at bottom of basket, but I too saw water just flow away out of of 'trellis' portholes, and put plastic covers over the lower rim of holes and left them unused which allowed more compost to retain water, I also used water retention crystals, but I do not understand why as yet all my plants have gone haywire this year, the petunias are 'finished' already but they grew far to talll and went over (absolutely beautiful when first flowered), the trailing plants have really struggled to receive water much as I have tried ! I do not manure my perennial plants and they too have gone skywards this year, much much taller than usual, even the roses have gone over with the weight of the flowers (never had that before). Just looked at row ofleeks that 'bolted' earlier and I had left them just to see the seed heads which are enormous and at the moment covered with bees!. The leek stems stand between 4 - 5 ft. Is that normal? I have never grown them before.