So you're saying I shouldn't have thinned them out, like you do any other kind of seedling? They were growing pretty well until the aphids arrived. And did you see what Monty said about the seaweed product he recommended? I suggest you have another look at the link I gave you. I can always try growing more basil from seed by whatever method is recommended at the time, but it seems I simply can't get someone to recommend a commercial aphid killer that they know from personal experience works like the ones Monty Don recommended, so I can get rid of the aphids that will inevitably appear on them. I shall have to rely on online reviews instead, Lord save me.
GW and Monty Don are on air from end of March to mid to end of October. NOt all of us find him to be a fount of all horticultural knowledge but I very much doubt he recommended sowing basil seeds at this end of the year in the northern hemisphere and at this latitude when daylight hours are short, light levels are low and temperatures fall below growing temps for most plants. Having got that bit wrong, thinning seedlings out is unlikely to improve matters.
Vendée - 20kms from Atlantic coast.
"The price good men (and women) pay for indifference to public affairs is to be ruled by evil men (and women)."
The insecticidal soft soaps recommended by Monty might be worth a try - I haven't used them for years, and never indoors. I don't think there's much to choose between the brands.* They should be marked as "organic" and "safe to use on edible crops". However, they will only kill aphids they touch, so you may need several attempts. And it's possible your basil will be stunted by the aphid attack.
Alternatively, you could remove the badly affected plants and concentrate on the one which appears to be immune.
Incidentally, @Obelixx is quite right about there being potentially too much room for the roots in the planter you describe. We don't have a photo so we're only going by your description, but - though it's counter-intuitive - you can give a young plant too large a container. There is so much compost that it never dries out and the roots remain in soggy surroundings. So it's not as mad as it sounds, to re-pot the plants into smaller pots until their roots fill them.
*Edited to say: I think the sort I used contained vegetable oil...
Since 2019 I've lived in east Clare, in the west of Ireland.
To Obelixx: I never said that Monty Don said anything about when and where to plant basil, by Toutatis! I only referred to his video about aphids.
To Liriodendron: One of my plants is, as I said, aphid free and is growing straight and true without any problems, if the compost around its roots is too soggy then it shouldn't be doing so by all these arguments. The plants are close enough together for their larger leaves to be touching each other, which I guess shortens the aphids' journeys.
I shall probably rescue the healthy one, though, and put it in the so far aphid-free back bedroom with a growlight and a heating mat on a thermostat. Then use the rest to test out aphid-busters in the kitchen - even if it's only starting with different brands of washing up liquid.
While it may not help the OP one thing I have done with potted plants to kill insects is drown them. the plant can hold it's breath longer than the insects! Put the whole thing into a large pot/bucket/bath pick the size that fits and slowly fill it with water. leave it submerged for 2-3 hours (probably overkill) pull it out and let the water drain do not water again for a while!
It doesn't matter what it says on packets. If you don't have the right conditions, it doesn't work. According to packets I can sow all sorts of seed in February. No, I can't - because my conditions aren't appropriate. The biggest mistake you've made is pricking out the seedlings. It doesn't work with basil. You sow - pots or trays - then take a clump of several seedlings and pot those up to grow on. This forum regularly gets queries about it.
I'd think @Obelixx is pretty spot on about the conditions too, but if you'd offered a photo instead of being so hostile, it would have helped. A trough with seedlings in it will contain too much compost - far more than is suitable, leading to difficulties with drainage, whereas small pots [2, 3 or 4 inch] contain very little, and therefore tiny, fragile roots can cope because they aren't permanently wet.
It's a place where beautiful isn't enough of a word....
I live in west central Scotland - not where that photo is...
@michael.hooker - plants don't read the books, so the healthy basil is probably doing ok in spite of having too much soggy compost around its roots. Perhaps it had a stronger root system than its companions.
Look on the bright side. If your healthy plant proves resistant to aphids, you could make a fortune...
Since 2019 I've lived in east Clare, in the west of Ireland.
Thanks @Liriodendron. They were all looking as healthy as the healthy one until the aphid attack. One thing I am trying is to tip the water out of the reservoir under the container inside the planter base and see if a bit of drying out helps. My house is not centrally-heated. If plants don't read the books I can pretend I never noticed that the reservoir level indicator has vanished from sight, after all That said, the soil does not feel damp.
As a 70 year old with Alzheimer's I find it necessary to rely on easily available reference material I can lay my hands on quickly, because memory of anything learned recently disappears far too fast. My father was a professional gardener in the 1950s and 1960s after being wounded in WWII and having to find a different career. He could grow anything, vegetables, trees, flowers, fruit bushes etc, with the aid of a single large book published just after WWII, and I often had to help him read it because his reading wasn't too hot and there were a lot of long words no-one ever used in East End schools in the early '20s, or in the Army. Sadly I never inherited his green fingers.
Posts
Alternatively, you could remove the badly affected plants and concentrate on the one which appears to be immune.
Incidentally, @Obelixx is quite right about there being potentially too much room for the roots in the planter you describe. We don't have a photo so we're only going by your description, but - though it's counter-intuitive - you can give a young plant too large a container. There is so much compost that it never dries out and the roots remain in soggy surroundings. So it's not as mad as it sounds, to re-pot the plants into smaller pots until their roots fill them.
*Edited to say: I think the sort I used contained vegetable oil...
To Liriodendron:
One of my plants is, as I said, aphid free and is growing straight and true without any problems, if the compost around its roots is too soggy then it shouldn't be doing so by all these arguments. The plants are close enough together for their larger leaves to be touching each other, which I guess shortens the aphids' journeys.
I shall probably rescue the healthy one, though, and put it in the so far aphid-free back bedroom with a growlight and a heating mat on a thermostat. Then use the rest to test out aphid-busters in the kitchen - even if it's only starting with different brands of washing up liquid.
The biggest mistake you've made is pricking out the seedlings. It doesn't work with basil. You sow - pots or trays - then take a clump of several seedlings and pot those up to grow on. This forum regularly gets queries about it.
I'd think @Obelixx is pretty spot on about the conditions too, but if you'd offered a photo instead of being so hostile, it would have helped. A trough with seedlings in it will contain too much compost - far more than is suitable, leading to difficulties with drainage, whereas small pots [2, 3 or 4 inch] contain very little, and therefore tiny, fragile roots can cope because they aren't permanently wet.
I live in west central Scotland - not where that photo is...
Look on the bright side. If your healthy plant proves resistant to aphids, you could make a fortune...
As a 70 year old with Alzheimer's I find it necessary to rely on easily available reference material I can lay my hands on quickly, because memory of anything learned recently disappears far too fast. My father was a professional gardener in the 1950s and 1960s after being wounded in WWII and having to find a different career. He could grow anything, vegetables, trees, flowers, fruit bushes etc, with the aid of a single large book published just after WWII, and I often had to help him read it because his reading wasn't too hot and there were a lot of long words no-one ever used in East End schools in the early '20s, or in the Army. Sadly I never inherited his green fingers.