I have to sow alot in guttering including sweet peas.............. I know don't shout, they need a deep root run, but the mice I have, don't appreciate that. But a lot gets grown in strips. I sow all sorts, Carrots, all climbing beans, lettuces, beetroots, swedes, turnips, kohl rabi, a row of annual flowers for the egde of footpaths or borders. You name it, i've grown it all in guttering. Never had a problem and is easy to scrape out into trench when they have grown a little.