Easy-peasy or a pain in the butt

I recently had a question about nasturtiums (Tropaeolum majus). A lot of gardeners don’t bother with these ‘easy’ annuals, leaving them for kids to grow. Anything so ridiculously easy to grow is not really suitable for serious gardeners, is it? I do use them here and there and, although they can self-seed too freely, I appreciate their volunteer seedlings, many of which I leave to grow. They are easy to identify and to pull out unwanted seedlings.

But are they actually easy to grow? The gist of this enquiry was ‘Over the last couple of years, I have nothing but disasters with my nasturtiums. One year black fly devastated them, and then cabbage white butterfly caterpillars destroyed them. This year I appear to have yet another problem, but I am not sure what is causing this.’

You can’t see the latest problem but it looked as though they were battered by wind or cold and the reason was probably caused by the plants being grown under cover, possibly on a windowsill, and then being planted out without being ‘hardened off’. Any ‘soft’ plant, coddled in warm, low-light conditions and then planted outside without being conditioned. can be damaged by cold, wind or scorching sun. Often the plants recover but it can be a check to growth. But back to nasturtiums specifically.

Because the plants contain similar, sulphurous chemicals to brassicas (to which they are not related), they attract some of the same pests. [the common name nasturtium is the same as the botanical name for watercress – which is a brassica – and means ‘nose twister’ because of the peppery taste – of both].

So nasturtiums are prone to cabbage white caterpillars and blackfly (aphids). I think that part of the problem lies in the oft-given advice that nasturtiums should be grown in poor, dry soil. This dates back to older kinds that have large leaves. Because they had large leaves, when grown in rich soil the leaves swamped the flowers, which were on short stems. This didn’t bother the bumblebees which flit among the flowers under the canopy but it does reduce their colourful impact in the garden. Plant breeders have worked hard to improve this state of affairs, most notably with the, now old, ‘Gleam’ hybrids with flowers that are better displayed. If you browse through any seed catalogue you can see new nasturtiums added every year so they must be more popular than I intuitively believe. There are now very dwarf kinds and the range of flower colours is quite compelling – who wouldn’t want to grow them?

Much of this is surely because of the belief that they are easy to grow and partly because they are the most edible of the edible flowers, which you would believe, if you listen to TV chefs, are an essential part of any meal! Take a piece of meat, vacuum-pack it in plastic, put it in a water bath so it is luke warm, throw away the plastic, flick a blow torch over it, burn a lettuce, cut tiny spheres out of an apple and compress them in another plastic bag and chuck the rest away, shave truffle on top, cover it in ‘cat sick’ (foam) and two drops of the litre of tarragon oil you made and sprinkle on some begonia flowers (and call them apple blossom if it is Masterchef) and voila – a Michelin star! Yes – can you tell it bugs me!


So we don’t need to grow nasturtiums in the poorest soil because they are now likely to be colourful even in rich soil. And then they will be less stressed and less likely to suffer from pests. But it remains a fact that these plants do get attacked by aphids and caterpillars. It is for this reason that they are often suggested for companion planting – planted among cabbage they may attract the butterflies away from your crop onto the ‘sacrificial’ nasturtiums. I am not sure. I will not get started on companion planting. But if you like the idea then give it a go – dwarf nasturtiums are unlikely to smother or harm cabbages and are better than bare soil.

Having said all this, although I did have some blackfly on nasturtiums in the first year, in this garden, I have not had the problem for the past two years and last year I didn’t even have any on the broad beans. And I had more nasturtiums in the garden last year than any other year and there was not even any caterpillars, though there were on the brassicas. How do I explain this? Well the nasturtiums are all in good soil or, in the case of the raised bed at the top of this post, well watered and fed. Maybe it is because I don’t spray (except for lily beetle when necessary) and I feed the birds. Blue- and great tits flit among the shrubs in the garden all year round. I have a spindle tree (Euonymus europaeus) in the garden that is the winter host of the black bean aphid. But I suspect that the tits eat these over the winter. I noticed overwintered aphids in clusters on a twisted willow last year, in dense clusters on the stems, but they were gone by spring. Although I often seem sceptical about ‘green gardening’, I am sure that tits and wrens are useful in the garden, mopping up insects – probably both good and bad.

I have rambled. The quick answer to the original question is that nasturtiums are generally easy but don’t abuse them just because they are easy. Give them a decent chance and if you do raise them under cover, harden them off gradually before planting them out in the garden.

And one more point. Although they are often classified as hardy annuals, they are killed, stone dead, by frost. The seeds will survive freezing soil, and they will self seed, but if seedlings appear too early, or if plants are put out too early in spring these will die.


8 Comments on “Easy-peasy or a pain in the butt”

  1. tonytomeo
    December 15, 2022 at 7:27 am #

    Dago pansies! I have been growing them since before kindergarten! They are both warm season annuals and cool season annuals here. Those that bloom through summer deteriorate through autumn, just as their seedlings come up to replace them for winter. Those that bloom through winter deteriorate through spring, just as their seedlings come up to replace them. They seem to be perennial.

    • thebikinggardener
      December 15, 2022 at 8:15 am #

      It makes sense that they would bloom, seed and grow throughout the year in frost-free climates. In fact, they are potentially perennial and there are a couple of double, sterile cvs rarely available here that have to be maintained by cuttings. You may well ask why bother but they are rather special and now I used to grow two of the three and hope to again soon now I think I have found a supplier.

      • tonytomeo
        December 16, 2022 at 2:05 am #

        I have not tried perennial types yet, but have grown some of the ‘annual’ types as perennial. At a former home, the mixed nasturtiums reverted to the common orange and yellow after only a few generations. Fortunately, those are my two favorite colors. Yet, there was a single red specimen that I wanted to retain. As it aged and began to deteriorate, I left the roots where they were, but buried much of the rest of the plant with only the tips of the stems protruding above the soil. They rooted and grew as new plants. As they deteriorated later in the season, I merely repeated the process. In the future, I would like to grow mashua, just to see how productive it can be.

        • thebikinggardener
          December 16, 2022 at 8:15 am #

          Yes the perennials I was referring to are cvs of T. majus. They are double-flowered so do not set seed but the species in all its forms can be treated as perennial – they just usually seed themselves to death. I have grown mashua (T. tuberosum) in the past and ‘Ken Aslet’ is the best form to grow here because it is not as daylength-sensitive so flowers earlier in the year – otherwise it only just manages before the frost. I would like it again but have never eaten it.

          • tonytomeo
            December 17, 2022 at 11:25 pm #

            Well, that is a good reason to grow it as perennial rather than replacing it annually, just like I kept my red bloomer going. (I know that they are potentially perennial, but they are more commonly grown here as annuals.) ‘Ken Aslet’ seems to be the popular cultivar for the mashua, at least among those who write about it. Pictures in catalogues often show a mix of cultivars. Since I do not know which to prefer, I might get a mix, and then subordinate those that do not perform well. Of course, I know that I can easier say that than do it, and will try to separate the cultivars and keep them ALL going. I will not grow them for bloom so much as for the tubers, which is ironic, since I grow the common nasturtiums for their bloom, rather than a vegetable. Incidentally, the primary problem with the common nasturtiums in my planter box downtown is that so much of the bloom gets taken (!). When I confront someone taking flowers, they simply remind me that the flowers are edible . . . as if everyone in the entire universe was not already aware of that, . . . and if that somehow makes it acceptable to harvest bloom that is there for the entire Community to enjoy.

  2. Paddy Tobin
    December 15, 2022 at 10:18 am #

    I’ll see how they go!

    • thebikinggardener
      December 15, 2022 at 10:27 am #

      I was thinking of you and your nasturtium seeds when I wrote that.

      • Paddy Tobin
        December 15, 2022 at 11:22 am #

        I’ll report progress in due time!

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