Planting partnerships to avoid

I was unaware of this as well Mamzie, but apparently marigolds give off a chemical that suppresses growth in some plants especially brassica and beans, the effect is called allelopathy and though the effect can stay in the soil for up to a year but adding compost to the soil increases the biological activity which will break down the chemical, you could ofcourse grow marigolds in pots close to the beans etc. as it's the roots which give out the chemical

I was unaware of this - maybe that's why my cavalo nero didn't do so well, given I planted some pot marigolds and French marigolds in nearby gaps!

The main one I pay attention to is alliums right next to legumes, for the same reason - allium roots give off chemicals that can affect legume roots, maybe because alliums are naturally antibacterial and they affect the nitrogen-fixing bacteria?

I think this year I may sow my marigolds along by the fence a couple of metres from my veg beds, where they will only have the new lawn and rose bush to compete with!