I think for now the solution is in how you set up your categories. Then do your searches by category. I only have 362 plants in my have list but I seldom have a need to search that. My most searched categories are my "Named Cultivar Daylilies" , "Daylilies on Order", and "Daylily Want List". I am not sure that is of any help, but I have found searching by category to be my best way.
Edited to add:
You could have a category for "Trees I Have", another for "Trees I Want" , "Trees That Grow Over Twenty Feet Tall" etc.
