Is it necessary to provide a hard divider between two different crops sharing the same bed ? The crops will be onions and potatoes.
In this case I would say no need as the two crops don't suffer from the same pests or diseases. In fact onions and carrots would be an even better combo as the carrot fly relies on scent and the Onion would mask that.
A very interesting link @shiney , I have read little bits about this before but we'll worth exploring more. Especially relevant now as a way of avoiding the need for pesticides and fungicides.
A lot of these have been used for hundreds of years. Something I was told, but didn't believe, 50 years ago was how to stop ivy coming through the hedge from next door. This was told to me by the man who used to come round on his bike to sharpen garden tools and knives with his bicycle powered grind stones and hand used stones. He said that ivy detests being near turnips and if I plant a row of turnips, close together, along the hedge the ivy was unlikely to come through. To my great surprise, it worked He said although turnips are not fully hardy the roots may even survive the winter as they would be partially protected by the hedge. They lasted about three years.
I think that the only caution would be to ensure that the onions are not shaded by the potato tops, especially when the potato haulms are fully grown. A string run along the potatoes to prevent them flopping down across the onions would help. As you may be harvesting the potatoes as earlies, leave sufficient distance between to enable you to extract them without knocking the onions down prematurely.
I just wonder how big the bed is, potatoes take up lots of space, are very hungry and water dependant. If the bed is fairly small I see the spuds just taking over.
I can't say I've ever considered a hard divider. I just plant with 12 to 18 inches between rows and then rotate the crops round each year on a three to four year cycle. What sort of divider where you thinking of?
