Brassicas

Question

I have a small raised bed which I use for growing vegetables. The soil has had quite a large amount of multipurpose compost added to it so has a fairly light peaty texture. The only nutrients I have added are my own compost from my bins and chicken pellets. Over the last year, any brassicas planted in the plot have generally only developed a small root system and the plants have failed to thrive. I don’t think it is club root, as I have not noticed any swellings on the roots. I have applied a collar to the plants to prevent cabbage root fly attacks but may have not done this soon enough. Also, high winds have blown the collars off regularly. The problem has worsened as the season has progressed. Can you help at all, please? (The plants worst affected have been recently planted sprouts and purple sprouting broccoli. I have also planted kohlrabi earlier in the year and have had a reasonable but not great crop from these)

Answer 1

Small root systems without a pest or disease normally indicate a phosphorous deficiency. I would add bone meal to the soil. Just as a precaution, I would also add potassium in the form of potash. It won’t hurt and may help the plants better use the phosphorous in the soil.