Id also add basil to that list. It just produces so well!
Dill, cilantro, and basil are annuals. Youll need to replant them every year. All of these will reseed if let to go to seed and you manage that area so they can sprout. Youll also have to learn how to recognize that sprout from a weed. They can take over an area if you dont remove a lot of plants and control them. Or you might learn to save seeds. I sow cilantro seeds where I want them to grow but use transplants for dill and basil. If volunteers are in a good location I might let them go or maybe transplant some.
Dill is a tall lanky plant. It may get 2 to 3 tall and spread out, oh how much, help me people, maybe 3. They are so lanky and the leaves so small, they dont provide any shade whatsoever. If you allow them to go to seed theyll die. I grow dill mainly for the seed heads for dill pickles. If you cut those seed heads off as soon as they open out, theyll keep producing for a long time. They are subject to dying if they get too dry. I recommend mulching to keep weeds down, cool the roots, and preserve water.
Im not sure how well Rosemary will overwinter in zone 5. That may have to be a container plant for you. I havent had much success with rosemary so Ill let others talk about that. During a garden tour this spring I picked up some hints from people here that have tremendous success with it but I want to try them before I talk about them.
Chives will keep coming back year after year. They need sun and dont like to totally dry out. Id give hem maybe 12 diameter to grow in plus whatever room you need so they can see sun. Maybe a southern or southwestern exposure.
Oregano is one that will take over if you let it. Its a perennial that may start out as a single plant but will become a huge clump. Every spring I cut back the outside roots of that clump to try to keep it under control. How much room? Depends on how vicious you can be trimming it back, but give it at least an 18 diameter for the clump plus some room for separation from the others. With oregano, as long as you keep cutting it back it will keep sending up new growth, but maybe a month before your first frost let it go so it can toughen up for the winter.
For some reason I have trouble with thyme but I shouldnt. Maybe I shouldnt talk about it much because of that. It should act a lot like oregano, forming a clump. There are different varieties that grow a little differently, some more upright, some more spreading, but all are pretty low to the ground compared to most of the others. If someone else tells you differently go with what they say but Id suggest a southern or southwest exposure so the others dont shade it out and give it maybe 18 diameter to grow plus a little shoulder room.
Cilantro will get maybe 18 tall and spread out a little, maybe 12 to 18 or so, but you can plant the plants closer together than that. They dont seem to last real long and will die real quick if you let them go to seed. Ive had success this year cutting them practically back to the ground, just high enough so they have room to send out new buds, just when they show the first signs of flowering. Ive let a couple go to seed so I can plant them next year. The seeds of cilantro are coriander if you want to grow them for that.
Basil is another that will keep producing as long as you dont let it go to seed. It will send out a bud at every leaf, so when you cut it back, just leave one set of leaves on that branch below your cut. It will keep growing and producing practically all summer. There are different varieties that will get different sizes. I grow the Italian types, Genovese and Lettuce Leaf. They can get maybe 3 tall and spread out close to that much. I think the sweets like Sweet Thai are smaller but they still need room.
I grow mine in a row at the end of my garden, herb row, not in a bed like you are talking about doing. The sizes I gave are the sizes of the plants themselves when grown in rows and given room. I dont know how tightly you can pack them in a bed but they will get big. Especially be careful of oregano. Its a bully and will take over. The cilantro, dill, and even basil could be overlapped a little if you plant more than one, but especially on the basil, dont overdo that. And layer them by height, short in front, tall in back, so they can get sun.
Good luck. I love having fresh herbs. And listen to those that grow them in beds more than me. My experience is a bit different.
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