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Some people say ts a good idea to plant Carrots , Onions and Leeks "together " to confuse pests and bad insects and confuse the carrot fly

I have 4 foot wide beds so do they mean plant them individually in a bed next to the others OR sow all in the same beds which to me seems stupid

Advice please Friends



The theory is that you alternate 2 rows of onions, one of carrots, two rows of onions. the onion smell is supposed to confuse the carrot fly. I must have intelligent carrot flies, because it didn't stop them. 18 inch high barriers of fleece or polythene work better.


Thanks FB

I cant see why carrot flies dont evolve so they catch on !!

I used polythene barrier this year and it worked


Stick to what works.If it ain't broke, don't fix it.


I've always grown alternating rows of onions and carrots and didn't have any problem with carrot fly for over 20 years until the last 2 or 3 when damage has appeared and steadily increased so it's barriers for me too next year.  Now they are present my normal crop rotation doesn't seem to help at all as the pupae overwinter in the soil so the emerging adults don't have very far to fly.  Lost 2/3rds or more of my crop this year to the little blighters.



From my limited experience of allotmenteering I would say that the unusual weather patterns recently have helped the little blighters to survive

I will use polythene sheeting again

I have spread horse manure on the beds ( not at home of course ) which may have an effect of the pupae

I have rotated my beds again and by choice I will grow onions , leeks and carrots next to each other

This is more complicated than being married !!




Onions and carrots side by side is good for many reasons....they complement each other. A good row of onions for me grows to more than 60 cm thereby providing another barrier to carrot fly.  The odour of onions does help confuse the carrot fly. 

Fleece is by far and away the best solution to carrot fly I think.  It is light, moderates temperatures and is aesthetically pleasing.  Polythene gets heavy with dirt and rain so can damage young crops and barriers look awful.   As soon as seed is sown cover with keeps off cats, etc., whilst germinating and warms the seed.  Being lightweight it does not weigh down the emerging carrots. It is easy to access when pulling carrots too.  I use metal U shaped pins to peg down the fleece

I agree that, along with everything in nature, pests are more savvy now.

Note that parsley too suffers from carrot fly.

I don't have a problem with carrot fly.....I use fleece early but have natural "barriers" around my veg patch, viz., a mixture of shrubs to one side, a lavendar hedge to another and a runner bean framework on another during the summer. 

My veg patch is smaller now so rotation is not really practised as well as it once was but, so far, it's effective 

I grow veg in rows grouped in 4.....viz., I have a tool that makes 4 rows 3" apart.  Each group of 4 is separated by 15".  I use this for carrots, spring onions, Beetroot, etc but onions are grown conventionally


Verdun......As usual brilliant advice and its recorded in my Lottie Notebook already

Thank you



I wouldn't put manure on the bed you are growing carrots in. It will make them fork.

Well said fidget .....I forkot to say that.......


FB & Verdun...............I have already manured the intended carrot bed on Dec 8th

Should I fork it in now or leave it

? What do you mean "Fork " and why will this happen please

Hello newboy

Carrots will not like freshly manured soil....they "fork" meaning they form fingers trying to divert away from the manure.  Stones in the soil too make carrots "fork"

For those carrots I would dig in your that it's already in the ground......and try to break up every lump.  Try to get at least 9" or so of the top soil as fine as possible.  Even on my sandy loam I cultivate further to get well crumbly soil.  I would do this 3 or 4 times before you sow carrots.  Also apply fish blood and bone prior to sowing and rake this in well too.


Ideally, carrots are sown on ground manured the previous year.


Thanks Verdun

I have now realised why the majority of my Lottie Neighbours say they dont grow carrots as it seems a lot of work but I will give it a go and start over the w/e with the first part

Think I may try a full bed or  half a bed....4 foot x 7 foot

The finer your soil the better your carrots will be Newboy ....hmmmmm, I can taste my carrots already 



What's your soil like, newboy2?  For carrots I add a *lot* of sharp sand as I garden on clay and it works well.  Carrots don't need a huge amount of food (unlike onions) so I just add a bit of FB&B like Verdun.  For clay soil, this method works well:

Dig a trench the width of a border fork (ie about 6") and about 10" deep, laying the soil at the side.  Sprinkle plenty of sharp sand on the removed soil so that it is about 50/50 soil and sand.  Mix well by raking over a few times, adding a couple of handfuls of FB&B.  Once mixed, rake back into the trench, firm a little and sow the seed, finally covering the seed with about 1/2" of the sand soil mix.  Any of the mix left over can be raked over the rest of the bed or removed and stored for later use with compost as a general potting mix.

A few years ago I saw a TV programme where a lighthouse keeper grew the most wonderful large carrots in the virtually pure sand of his little island.  All he used was a bit of composted seaweed mixed with the sand so they don't need that much fertiliser to grow well.  I think he was on one of the Scottish islands so the growing season must have been relatively short, too.

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