Plants to avoid:

I love Centhranis Ruber. So much so that I feel sad when it gets cut back.

I keep it contained to the gaps at the bottom of my fence but it’s a great plant for intermingling with others I think.

 

@BellaBlue Glad you posted those photos, I was actually thinking of that first one as a nice example of Red Valerian being allowed to do its own thing from when you posted it in the roses thread! What's that white flower growing with it in the second photo? They go well together and it looks really familiar but I just can't remember what it is ATM!

Nick

 

I like centranthus good for poor soil or difficult spots, I grow it along the fence next to the road where their barely any soil .

 

Back in early summer, I posted a picture of large swathes of centranthus growing on the Towans.....metres and metres of pink, white and red. Amazing sight....Mother Nature does us proud at times.

However, it likes to romp and spread and not really a garden plant, esp if in small to medium gardens I think

I used to call on someone in Newquay...overlooking the sea......and her gardener had planted some in her garden. Within 5 years, as a guess, it had dominated her entrance. Lovely to look at in summer but it was bullying large shrubs and other perennials alike.

Whether it grows well in a container I don’t know

Seems to me Bella Blue has sited hers well and it does look good there

 

@Nickolaos That is the annual Ammi Majus. Lovely floaty thing. I want more of it next year.

@Verdun Thank you. The foilage isn't the prettiest after flowering so having it near other plants or containers gives you the best bits. The flowers. My garden sense is developing lol

 

BellaBlue....developing nicely though

 

Yes I am especially wary of the runners.

That's actually why I'm rather hesitant about Primrose/Cowslip/Oxlip (Primula Vulgaris/Veris/elatior).

There is a lot of information to suggest that whilst they do seed quite readily, they don't really 'take over' so much as slowly form little clumps in spots they like and stay confined there and then if it's too much then you just dig it up and divide them. However often not mentioned is that they (as I understand it) all to one extent or another produce runners, which then form new plants, which I don't know if that could pose a problem in terms of removal if they did turn out to be problematic.

Whether such a process, at least in this instance would be able to compete with/push out established larger plants like Fuchsia, Ice plant, Phlox etc or not I don't know? But it's a useful example of the problems involved in researching this as for all the positive comments about what a useful, trouble-free plants they are, there are always a few points to give you pause.

 

Umm, I’ve grown primroses and cowslips for years, decades even. (I have no experience of oxslips, so cannot comment). I have never known them to produce runners of any sort. Unless you are referring to the offsets that they, like other rosette-forming plants, produce. Ie a smaller rosette to the side of the main rosette.
My experience is quite the opposite - that they are frustratingly slow to form small colonies. Any seedlings are slow to establish, taking 2-3 years to reach flowering size. The seedlings can be very easily identified, pull out easily, and any remaining roots do not form a new plant. The seedling roots are also quite delicate, so do not transplant that easily.
Certainly they are not plants to avoid because of fears of invasive tendencies!

As to competing against larger plants, again, I think any fears are unwarranted. The three examples you give are summer/late summer flourishers. So the primrose /cowslip will be going into a semi-dormant state when the fuchsia/ice-plant/phlox will be coming into its own. These plants are also more vigorous, and with time would overpower the primulas...

Basically, don’t dismiss primulas as potential thugs!

 

Primulas are well behaved here....never thought of them as thugs at all. As Sian suggests, they will happily and modestly assort with all sorts of plantings.

 

Violets get everywhere in my garden, they crowd out things, pop up in the middle of clumps etc. Certainly nothing shrinking about them. Having said that they are an attractive flower under the trees and there are a couple of patches of white ones.

 

I can never see the point myself. To open up properly and do what they should they need good sunlight which has been rather lacking over the last few springs.

Not hardy

Forget them! Self seeding weeds in my opinion.

I agree!

I understand that D.purperea doesn't fit in with the more exotic theme but what about Digitalis ferruginea?
Digitalis ferruginea by longk48, on Flickr

Digitalis ferruginea by longk48, on Flickr

Other plants to avoid include the common forms of Crocosmia, Japanese Anenome, Teasel, Malva sylvestris (wild mallow), choose Daylilies carefully and Amaranthus if you don't want to have to be vigilant over seedlings.

 

Forgot about that

We do have ferruginea in a pot. Only one of the plants is flowering

 

@andrews - get it in the ground. It will make a fine but understated specimen.

 

One other aspect of mixed planting is allelopathy....the ability of some plants to produce chemicals which inhibit the growth of others nearby. Allelopathy - Wikipedia
Cistus and Salvias do really well here, but it's remarkable how the perennials and even other shrubs planted near them fade away. They are the two main examples, but I think there's a connection between all very aromatic plants like lavenders, thymes, Marrubium etc. and this ability to suppress the competition!