Earlier this year I bought a lean-to greenhouse no. 69 (5'4" x 6'8") which was erected in May by my son-in-law who is adept for such an intricate and precise a job. Now that the growing season is over I am able to congratulate you on such an excellent product that looks well and oozes quality. One possible improvement is suggested in the attached sketch. The re-arrangement of the glass panels on the door-side so that the door is a "narrow panel width" from the wall would provide access to a three-slat shelf along the wall and thus increase the versality - of particular value to those who, for various reasons, have difficulty in bending.
In a previous greenhouse which I built of wood I was able to adopt a capillary system by being able to slide a water container under the slatted shelves. I think the same system can be fitted to your shelving slats given that a simple Z shaped slide with appropriate bolt holes is available - 2 pairs would meet the needs of a 7' length. I leave you with the thought for what its worth.
EXTRA NOTE - A SEPARATE SHEET WAS ENCLOSED WITH TWO SKETCHES SHOWING DETAILS OF THE TWO SUGGESTED IMPROVEMENTS. THIS LETTER WAS FORWARDED TO THE PRODUCT DEVELOPMENT TEAM IN THE TECHNICAL DEPARTMENT.