Did you water thoroughly after planting? Transplanting annuals in full bloom in midsummer I'm not surprised they sacrificed some flowers. I don't think it's anything to do with sun, in fact they may have got too much too quickly.

Might be summer heat. Alyssum peter out here by mid-summer. For me they're strictly late spring-early summer filler plants.

@floraluk2 If anything they have gotten too much water.

If they were fully in flower, there could be some transplant shock. Try giving them a haircut and see if they'll set new flowers.

They bloom in every sun/shade condition in my yard. Even under the trees. Not nearly as full and beautiful, but still pretty nice. I would agree most with sandyslopes. Though, they do love it cooler. Could just be the heat.

Agreed. They flower intermittently even in winter here. Not too keen on them myself. They self sow and look fairly weedy.

I dunno. I like that they flower all winter here. Better than brown ground. I need to get some primula or bergenia... something that would get me over the hump. But alyssum looks good amongst pansies. Which also bloom all winter here.

We're in June. Only 3 weeks to midsummer's day. And OP is in California. I agree that transplanting them in full flower is not conducive to happy annuals.

Isn't midsummer the middle of summer? I.e. somewhere in mid-August? Isn't it three weeks to the START of summer? LOL am I missing something? Is there some traditional meaning ascribed to "midsummer" that really isn't the middle of summer?

:)

Dee

I think of summer solstice as the beginning of summer , in about 2 weeks

Mid August to me is almost Fall. I think of mid June to beginning of July as mid summer, or whenever summer blooming plants are blooming the most...lol.

Midsummers Day is June 24th. That's when we have the longest period of daylight. I used the term 'midsummer' to mean that time, not necessarily the hottest time of year.

Technically, the start of summer is a date in June. Among the peoples, where I live "summer" is June-August; Memorial Day kicks off the summer season and Labor Day wraps it up. So "midsummer" around these parts is the month of July.

Hot weather can occur earlier or later than that, though -- obviously. Cool season annuals, which alyssum is, do not do well in hot weather. A few days here and there no problem, but longer stretches and they're done. That's usually early to mid July for me; same with violas (Johnny jump-ups).

Astronomical Summer starts on the solstice, the longest day of the year sometime around June 22/23.

Meteorological Summer is based on average temperatures and begins June 1.

In *some* European cultures, the summer solstice marks mid-Summer.

So you can take your pick and you are all right :)

Here is a photo of my Alyssum. The three red oval areas are either dead or dying. They look like they are drying up, but the pot has been getting if anything too much water.

Those are toast. Remove and replace with something fresh.

Yes, they're not worth bothering any longer with. If the idea was to attract beneficials you could use something else better suited to your conditions. Don't ask me what that would be. Some more marigolds perhaps? But open faced ones, not doubles.

@floraluk2 I have Marigolds on the outside ring of the container, Sweet Alyssum on the inside.

@porkchop_z5b_MI Right they are dead, but my original question was why did they die.

Yeah, they look fried. Too hot for them. Try again in autumn or March-ish

Um, am thinking the OP's mentioning 'too much watering, if anything' is more likely to be the answer. Alyssum does not relish waterlogging in heat - suspect rotting rather than drying out is more likely to be problematic.

TBH, I don't really consider alyssum is an ideal candidate for pot culture either - it likes to spread out, with shallow roots, blooming in spring and again in autumn, doing nothing much in summer apart from surviving, but not really flowering.

Rotting. Oh. Ok then, I can see that. I never really took them for such sensitive roots, but maybe so.

"I have Marigolds on the outside ring of the container".

I know. I can see them in the picture. That's why I said "more" marigolds.