Q: My neighbor and I have tried to grow radishes in pots on our decks but we have failed to get what we want. We get lots of green tops but undeveloped roots. We have grown the ones that are supposed to grow in containers such as ‘French Breakfast’ and ‘Cherry Belle’ but we have not had anything close to success. We are both stumped. Is it the soil, depth of soil, or moisture?
A: My bet is that poor soil drainage, and perhaps over-fertilization, are the problems. Try two experiments:
1. Potting soil tends to hold too much water to make a radish happy. For your next planting, mix high quality potting soil 2:1 with perlite in some of your containers, thus improving drainage.
2. If the potting soil is pre fertilized, let that be the extent of your feeding in a couple of your pots. In others, fertilize only once with a high phosphorus houseplant fertilizer.
One or both of these experiments should bear results, and radishes! See what happens and let me know the results!