We moved last autumn. The veg patch was covered with black plastic but on peeling it back we found that the previous owners had had a bonfire on part of the patch. Anyway dug the lot over at the start of the season and all is well at the moment apart from my courgettes. I planted four plants, two are fine but two have yellow leaves. I don't know if it has anything to do with the bonfire (they are planted roughly in that area), or whether they need a good feed. Any ideas anyone? What should I feed them with? They have been in about 3-4 weeks and are growing. Haven't a clue if anything was grown on the land last year and if so what.