I am in a (unimportant - prize is worth $5) competition to grow the biggest radish within 4 weeks. All of us have seeds from the same packet (10 seeds each), but other then that we have cart-blanche as to how we do this.

The only metric that matters here is weight of the biggest radish "bulb".

There seems a paucity on how to grow radishes and optimize for speed on the Internet - so any advice would be useful. Some questions I would appreciate any insight on -

  1. Are the ideal conditions "as much light as possible" with an ideal temperature of about 20 degrees C in a loam soil that is kept very moist?

  2. What do I want to do as far as fertilizing goes? I've read that Nitrogen rich fertilizer is good for growth, but also read that it makes for a very leafy radish with not much root growth? Somewhere I read about radishes wanting phosphorus? (Will Phosphoric acid help, and if so at what kind of quantity - I happen to have some available to me). How do I balance its pH if I add phosphoric acid?

  3. What is the minimum amount of darkness I need for radishes to grow (i.e. if I take them out when its sunny and bring them inside when its not? I don't exactly have a grow lamp, but I have some bright white LED's which may help at night.

  4. It is spring here, so temperatures outdoors range from 9 to 25c. How much do I need to care about temperature fluctuation?

  • 1
    That sounds like a fun competition, good luck! :)
    – MackM
    Oct 17, 2023 at 12:52
  • 1
    Hmm. There should be some info (or closely guarded secrets?) since people do enter other competetions for prize-size vegetables, though some end up being a bit silly (i.e. longest carrot, and getting the longest bit of tiny root at the end of it is part of the winning program - but they are still unnaturally large carrots... anyway!
    – Ecnerwal
    Oct 17, 2023 at 21:47
  • 2
    Whatever happens, we want photos and perhaps a self-answer. Thanks for a fun question!
    – Stephie
    Oct 18, 2023 at 5:29
  • 1
    Meh. I'm having trouble getting to actual pages of people doing it which were a delightful read when I stumbled upon some years ago (they are usually not time-constrained as you are, though I suppose with radishes they'd go to seed if given a lot of time, but e.g. atlasobscura.com/articles/growing-giant-vegetables Now I keep finding bot-scraped nonsense pages with lots of ads for most results...
    – Ecnerwal
    Oct 18, 2023 at 13:17
  • 2
    @Brōtsyorfuzthrāx We have 21 days which started 26 Oct 2023. We were given 10 seeds (not packets, just 10 seeds) of the "Mila" variety. This is described as "An early variety producing cylindrical red roots..." Packet says they can be sowed all year round. I'm currently pondering limiting their sun exposure to 12 hours per day - which sounds counterintuitive, but I have read that Radishes are "long day" plants and will bolt if they receive too many sunlight hours - and going into summer we get more then 12 hours already.
    – davidgo
    Oct 21, 2023 at 5:12


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