does anyone have any allotment/ vegetable planting advice they can give me? I have a small patch in my garden (~6m2) by a fence with ~6-8 hours of full sun in the summer and it is a clay soil. Ive been adding some mulch to rot in over winter and I want to grow potatoes, onions, tomatoes, brassicas and some other stuff and want to know how best to make use of the small amount of space to get a good and healthy yieldzylphide
this got kinda long i'm sorry, i'm a plant biologist jksdfsd
clay soil is dense and needs to be aerated somehow to introduce air into the soil and improve drainage. mulching might be enough, but i would look into it some more to make sure.
certain plants HATE being planted next to each other, for a variety of reasons. either they produce compounds that another plant can't tolerate, or they attract similar/the same pests and you'll get a horrible infestation that hurts both plants. (look up companion planting and maybe allelopathic plants if you want more details)
recommendations for the plants you've listed:
since your available space is not that big, i'm not sure you can follow all the reccomendations and still plant all the crops that you want. you can definitely try, but i'm not sure if you can space antagonistic plants far enough apart to avoid the adverse effects.
each plant has its own reccommended spacing between rows. bigger plants will generally need more space.
to grow potatoes, you probably want to grow them "upwards." idk how to properly explain it, but the potato part of a potato plant is actually a modified stem, so what you want to do to get more potatoes out of the plant is to plant the initial tuber into the ground. after that, as the plant grows taller, you need to add more soil around the stem. you can use something like a canvas bag with holes cut into it to keep the soil in place (the holes are to check the tuber growth status/harvest the tubers). this vertical farming helps to maintain empty space for other plants.
highly reccomend any kind of tomato cage for tomatoes to grow on, which may take up some extra space depending on the type of cage you buy.