With such a small boring rectangular space, you certainly come up with many creative ideas to try things outside of the box.
Especially love the ways you consider using perennials to aid the new annuals.
Last year I had a long horizontal shoot from my grapevine, and it worked well with the other vinning annuals, like pole beans, to climb over. It is so fun to pick off the beans when grown like a string of christmas lights within arms reach.
Last year, my second year sage plants were also over producing. I was just discarding old leaves and completely forgot you can burn them to cleanse the air of toxic stress. The scent of the sage and lavender I have witnessed also calms the air for nearby vegetables by warding the aphids away. Especially helpful beside new plants in the brassica family.
I still have a hard time with cilantro. For me they only sprout in very rich, wet soil kept in the heat, yet everyone says they like the cold and shade. Know any secrets to get strong roots for tall leafy branches? I have tried planting many seeds close together, and they do seem to benefit when young as they tend to fall over otherwise. My guess is they probably need a constant dose of liquid fertilizer to energize the growth, because organics top dressing fertilizers do not spread deep enough into the soil later in the season.
Yes, I definitely need to think outside the rectangle, hehe!
I have some lavender plants I started indoors a year ago. Maybe I plant one outside in the bed, on the herb side but they get really bushy, I've seen, and I don't want it to take up a lot of my precious space but I guess it's worth it, isn't it?
Grape is something else I want to try growing! I had that Christmas light effect too and it was arching over my pathway beautifully. Makes me think I need an actual arch....
I actually avoid planting brassicas altogether out of (an irrational) fear of attracting cabbage butterflies!
As for cilantro, I don't know what to tell you. One gardeners ease is another's bane I guess. I just scatter the seeds on the ground and they all sprout, grow strong, and then go to seed without any supervision or babying. They are so successful that I actually have to cull many of the new year's seedlings to make space for my favorites (I can't even enjoy raw cilantro due to a gene I have).
Let me think. My soil is not particularly rich, I think. I'm trying to build it, but then again I've been saying that for the last few years so maybe it is! They do need water though. The plants that sprout in the corners never do well due to the dryness...
If all else fails, maybe try scattering some seed in the fall before light mulch or even now but I guess you can't really work it into the ground right now if the soil is frozen.
Sorry I couldn't be of more help
Try growing invasive rooting smelly plants in small pots. Then you can move them around to benefit any plant in the garden without worrying about root competition.
Thanks for all the follow-up comments!
Did not know there is a gene responsible for how we taste cilantro. Many people who dislike it believe it tastes soapy, to me it is more like mild parsley. I love it raw too.