Perennial annuals

Sunday, 05 October 2014

Mystery Tagetes in my garden

This week my thoughts have turned to some plants that I find confusing. Plants that don't behave as we might expect them to - plants that I have always thought of as annuals that behave as perennials. My first example is a marigold plant, which I obtained as a cutting last November. It has gorgeous tawny-orange single flowers, each petal edged in yellow - and has grown into a small shrub! I fully expected it to die off over winter but it emerged unscathed and is covered in blooms. It is not the true shrubby perennial Tagetes lemonnii, which has quite different foliage. I don't know what to make of it - but I adore it!

Yellow wallflower that acts as a perennial; garden of Margaret Chedra in Sydney

This spring I have noticed many gardeners growing a brilliant yellow wallflower in their gardens - some sort of Erysimum. There are definitely perennial wallflowers (such as Erysimum mutabile) but there are also those that I have always thought of as annuals or biannuals - most likely to be Erysimum cheiri. One friend who had this yellow one growing said it had been raised years ago from seed and said to be an annual, but had never died! And that it would grow from a cutting. Like the traditional perennial type, it likes sun, good drainage, a little lime in the soil and trimming after flowering. I now have a piece myself to try. In its native habitat, it is regarded as a short-lived perennial.

Dianthus Olivia

Another plant that seems to blur the distinction between annual and perennial is Dianthus. I have never had any success with the silvery-leaved perennial Dianthus, which look like mini-carnations and I think are referred to as 'Modern Pinks'. The only perennial form I have had luck with is a superb and vigorous green-leaved one with hot-pink flowers (ht 30 cm), which I have had for years - possibly a strong cultivar of Dianthus barbatus or some sort of hybrid form. I never thought to grow the annual bedding Dianthus chinensis until I noticed a white form in the garden of a friend, which never seemed to get pulled out! I took a cutting and it grew into a large, flat mat, which seems to flower all the time and has lasted more than two years. Possibly it too is some sort of hybrid form. Like the wallflower mentioned about, both Dianthus barbatus and Dianthus chinensis are actually short-lived perennials in their native habitats. Buoyed by my success, I have just bought another low-growing one, with burgundy-edged white flowers, called Dianthus 'Olivia', which is a hybrid. Dianthus likes the same conditions as wallflowers.

Flowers on our freaky tomato plant

Yet another example is Salvia splendens, which I always regarded as an annual; however, it is perennial in my garden, flowering all the year round in colours of red, pink, purple and salmon. It reaches the dimensions of a small shrub, and is pruned back in late winter. Nicotiana is another genus that lives on from year to year in my garden, and can be propagated by cuttings. I even have a tomato plant that survived this past winter (in a pot) and is bursting into growth again after a pruning in late winter! It originated in the compost heap, from where it was rescued by an enterprising daughter. It had an abundance of fruit last summer and I am hoping it will do it all again this year. It is already flowering!

Browallia americana

Other annuals in my garden are basically perennial because they drop such a huge amount of seed each year that I have hundreds of seedlings that come up the following year, so I am never without them. Chief amongst these are Browallia americana, Amaranthus caudatus, Orlaya grandiflora and Atriplex hortensias 'Rubra'. I do shake the plants around as I pull them out, to make sure I get more seedlings next year!

Plants we regard as annuals and perennials are often not based on absolute definitions - their growth patterns depend on where they are grown. Whilst there are no doubt plants that always complete their lives within a year, no matter where they are grown, many traditional 'annuals' are in fact perennial plants in their native habitat; or in the case of others, are perennial in places that are warmer than their native habitat. In the days when more space was allotted in gardens to grow bedding plants, they would be pulled out at the end of one season to be replaced by the next season's seedlings, and were so easily grown from seed that people made no effort to keep the old plants. In our modern gardens, with less focus on massed bedding displays, we perhaps have more freedom to allow plants to linger on and show us what they are really capable of in our mild Sydney climate.

This pink Salvia splendens is like a shrub, not an annual, in my garden

In colder climates, Salvia splendens, for example, would not survive the winter, so would definitely be classed as an annual. Similarly, plants we in Sydney regard as resolutely perennial, such as zonal Pelargonium, marguerite daisies, Verbena hybrids and even Pentas are treated as annuals in cold climates. It is really worth experimenting with many 'annual' plants to see if they can be coaxed into living longer in your garden; and also trying to strike so-called annuals from cuttings, especially if you see something unusual in the garden of a friend! It is possible that it is just some very strong specimens within a species that survive, like my hot pink Dianthus: these are surely worth preserving in our gardens.

I am still confused about my strange shrubby Tagetes but I am enraptured by it as it adds such a bold smudge of hot colour at the moment, alongside brilliant yellow, long-flowering Osteospermum 'Voltage', the slim lemon spires of Bulbine frutescens, orange and red Gaillardia and smouldering purple Babiana.

Reader Comments

  • By margaret 2122 Monday, 06 October 2014

    I agree with your comments, having a selection of the plants mentioned survive for years in my garden. As well, each year, so-called annuals - primula, poppy varieties, linaria, cornflower, calceolaria and viola self-seed, adding their welcome colour to the mix. I always cut back petunia and pansies when they finish flowering, and always have a second (or more) season from them. It is well worth knowing that this can be done. I think I was always in the mindset of pulling them all out at the end of each season! Deirdre

  • By yvonne 2154 Monday, 06 October 2014

    i love seeing the plants you have all got i have a piony which i bought two years ago i am still waiting for it to flower ,i am allso a lover of salvia i have a ilac one but mainly red , allso i didnt know there were so many colours of zinnia ,can you tell me if i just cut them back when they get stragley or pull them out Yvonne I think it is worth cutting them back just to see what happens. Give them some liquid fertiliser at the same time that you cut them back. Deirdre

  • By Norman 2653 Monday, 06 October 2014

    hello; i found the bit about annuals = perennials most interesting. all the best wishes to you & your family. Thanks, Norman! Deirdre

  • By Patricia 2100 Monday, 06 October 2014

    Some scented pink Dianthus Candy Floss which were bought in flower in 2012 produced not one bud last year. This spring they have masses of them and flowers are eagerly awaited. It will be interesting to see what happens next year. Biannual flowering is just another new and joy-filled gardening event. Always appreciate the lovely photos and plant info. Great that your Dianthus have flowered so well this year. I am hoping my new one will survive for a few years at least. Deirdre

  • By noeline 2081 Wednesday, 04 October 2017

    I have had 3 different coloured flowers on dianthus chinensis come up in my garden for the past 4 years and am waiting to see if they pop up again I also have a second flush of spreading petunia which i planted last spring it is flowering better than last summer goes to show sometimes not ripping annuals out quickly pays off in Sydney. Thanks, Noeline. That sounds great re those dianthus and petunias. It is interesting to see how things can survive from one year to the next and worth experimenting! Deirdre

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