What causes radishes not to bulb?

ania_caMarch 7, 2011

I have 2 very large containers with radishes. They are next to each other, same soil and same care. One container full looks normal and the ones in the other container are not bulbing. I'm not sure why. Any ideas?


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Some of the variety's are the same and some are different. I think I planted a row of cherry bell's in both though. The ones that are not bulbing are cherry bell, black, french breakfast, watermelon and white icicle.

On the other side, cherry bells, white and purple are bulbing nicely.


    Bookmark   March 7, 2011 at 12:25PM
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girlgroupgirl(8 ATL)

i have this problem sometimes. It seems to me, usually to be soil temp. I now grow specific radishes at different times of the year and have had less trouble.

    Bookmark   March 7, 2011 at 1:48PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

Too much nitrogen in the soil causes big tops but no root bulbs on most root vegetables, radishes included, as does too deep planting.

But if both pots are the same - same size, same potting mix, same watering and fertilizer, same planting depth, and same seeds then weather/exposure remains the only variable I can think of. But the odds highly favor one of the other variables being the problem.


    Bookmark   March 7, 2011 at 1:58PM
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The one planter gets a tad more shade, but not significant. They are pretty much both full sun except the one gets a tad of afternoon shade cause it's closer to my wall. And I have not had any trouble with it's location before with sun loving plants.

Most of the radishes that are bulbing are faster maturing radishes but I'm concerned that the ones in the other planter are just not going to bulb. The plants look leggy.

I can't figure out how long to wait to see if they will bulb or just pull them and plant something else. If they are not going to bulb, I could use the space.

What's normal for french breakfast, icicle, and black radishes. Is it normal for them to look like this while others are bulbing?

What concerns me most is I'm pretty sure I planted a row of the cherry bells in both planters that those look way different. The ones in the other planter are almost ready to be pulled.


    Bookmark   March 7, 2011 at 2:22PM
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Icicle, Black Spanish and Watermelon are long season radishes. French Breakfast should compete with Cherry Belle for earliness. Icicle takes about about a week to 10 days longer. Black Spanish and Watermelon take about 20 more days. These are normally considered winter radishes.

    Bookmark   March 7, 2011 at 3:58PM
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Thanks, that is very helpful. If I don't see bulbing in 20 days, I'll pull them up and put some squash in there.


    Bookmark   March 7, 2011 at 6:12PM
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One final caution, The latter three are large radishes. Icicle gets carrot size or larger , Black Spanish Round and Watermelon get turnip size or baseball size. They don't take to crowding.

    Bookmark   March 7, 2011 at 7:01PM
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They are well spaced. Their planter is 4 ft long, 3 ft wide and 2 or 2.5 ft deep so plenty of space and I spaced the seeds out a lot. They shouldn't need thinning until they are regular radish size....if they would just start bulbing :)

    Bookmark   March 7, 2011 at 7:16PM
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Sometimes radishes just won't bulb. I had very different results with the same variety from different suppliers. You never know. But this year I realized something. Do you know the rat-tail radishes, the ones that are grown for immature seed pods rather than roots? They are fairly big for radish plants and just "bolt" at once - that is what they are supposed to do. Well, what I realized is this: all immature radish seed pods are edible. The trick is not to let them overgrow and become tough. This year, when my radishes refuse to bulb and start bolting instead, I'll try and wait for the pods. If it works, I'll never be upset about bolting radishes again. It will be one way or another.

    Bookmark   March 8, 2011 at 12:06PM
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I have a question about this as well. With daikon radishes (big Asian white radishes) will they not bulb properly if overcrowded? Are asian radishes (NOT ICICLE!) considered a winter radish (one that grows well in spring and fall). On the other hand is it something that won't develop the root properly if it's grown in hot weather, or can it be grown year round and doesn't care?

The reason I ask is because I tried to grow radishes last year and they were spindly with the root portion. I'm wondering if the hot weather caused this? I grew these in early to mid summer, which for my zone (gardenining zone is 5) is early to mid May. Live in the upper part of the lower peninsula in Boyne City Michigan. Summers are milder compared to summers in southern climates, but still hot in summer.

    Bookmark   March 8, 2011 at 12:45PM
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jimster(z7a MA)

The question about failure of radishes to bulb up is raised here frequently. Many reasons have been suggested but there seems to be no positive answer. One seemingly sensible answer is failure to thin them soon enough and widely enough. Another is failure to maintain soil moisture. But it remains a mystery to me. A search of this forum will lead you to previous discussions of this topic.


    Bookmark   March 8, 2011 at 12:51PM
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I'm pretty sure now that it is too little K in relation to N. I just got to my florida place, and radishes that I planted in early december with a little very aged compost and a good dose of oak wood ash made colossal roots - about as big as I've ever seen. The french breakfast are some of them nearly the size of tennis balls. Some are still edible, amazingly. I wasn't here to thin and some are crammed right up together, still huge. Planted as the daylength was declining: so much for that theory.

Wood ash is quite high in potassium, and has some P. No N. I now realize that K is critical for all roots and tubers. It gets sucked up very rapidly in gardens - using enough wood ash to keep up could result in overly high ph and possibly P. Sul-po-mag could be a good option, unless one has plenty of good finished compost, which most of us don't. One needs compost with mineral salts - including wood ash - in any case, to buffer.

    Bookmark   March 8, 2011 at 6:06PM
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Here is one:

    Bookmark   March 8, 2011 at 7:21PM
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I think it was lack of sunlight. I was looking at it over the weekend and the radish container where they are not bulbing gets less sun. I trimmed a few branches back above it and it should be OK now. Hopefully, they bulb.


    Bookmark   March 14, 2011 at 3:09PM
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Radishes are interesting because they are the easiest thing to grow, except when you run into the problem of them not bulbing... Keep a pH of around 7 (neutral) for your soil. Use new soil and not just a random bad area in your yard. Radishes like a sandy loam as well, so mix in some sand with your soil, and keep it "loose"... They have to be able to push the soil so having it compacted won't do you much good. Keep soil moist at all times. Great information can be found using the link I attached. Recipes, growing, preservation, etc.

Here is a link that might be useful: Radish Garden - Healthy Snacks, Recipes, Growing & Preservation

    Bookmark   March 31, 2011 at 4:09PM
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They are bulbing now. The cherry bells look good and the big guys....the icicles, french breakfast etc...look to be starting to bulb as well.

No sign of the watermelon radishes bulbing yet.

    Bookmark   March 31, 2011 at 4:21PM
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OT but I will post anyway because I think others have properly addressed Ania's radish dilemma and the discussion needs no input from me. I hope the OP can solve the problems. :-)

KatyaKatya mentioned the young radish seed pods being edible. A person can also let some of the seed pods mature to harvest the seed for edible sprouts and for planting next season.

For such a lowly, somewhat disrespected little vegetable one gets a lot of bang for the buck. Roots, leaves, pods, and seeds can all be consumed. Sprouts from the seeds can be consumed, and the seeds can easily be harvested and saved for next season. (Being mindful of cross pollination issues of course.)

If interested, check out the link below to see my slideshow.


Here is a link that might be useful: How to harvest radish seed.

    Bookmark   March 31, 2011 at 4:41PM
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seysonn(8a WA/HZ 1)

Lots of posts. I just glanced through.
Let me tell you an old world secret to make your radishs, especially the long season ones, to bulb;
When they have about 4 big leaves, STOP watering them. Let them to get really really thirsty. You will see their leaves get darker, laying down on the ground. What happens is that the roots dig in deeper and deeper searching for moisture. Then comes the time to deep water them.
The problem with this method that I have had is that what can you do if it just keeps raining? I dont do anything the. just let it go. I am not going to fuss too much.

    Bookmark   March 31, 2011 at 9:05PM
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I planted Cherry Belles back on 6 April. It has been a cool damp spring here. I attempted to harvest the radishes today - and this is what most of them looked like. I got about half a dozen radishes that were about 1/2" diameter - but the rest was this.

Is this a soil problem? Or the fact that the leaves were close to 2" high before I thinned?

    Bookmark   May 25, 2011 at 7:41PM
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Pixie, you can cut off the leaves to eat and put that root back in the soil. It may grow leaves again, and may bulb up later, if there is enough P and K to bulb.

    Bookmark   May 25, 2011 at 9:34PM
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