Kate WallEvery plant has a lifespan and needs care in old age

Yes it does happen. Like us, plants are living creatures and their days are numbered. For some their number of days may be a very large number, for others not so large, but regardless what that number is, no living thing is truly immortal.

Coleus - this plant tends to be fairly short lived (less than 5 years) but can die very quickly when things get too dry or wet, so by taking cuttings regularly a fresh young plant is always available to fill the parents space

Coleus – this plant tends to be fairly short lived (less than 5 years) but can die very quickly when things get too dry or wet, so by taking cuttings regularly a fresh young plant is always available to fill the parents space

 

A few times recently people have asked me what is wrong with their tree, to which the best answer is “old age”. I’ve had other gardeners complain to me that their flowers keep dying and on investigation I found they were growing annuals and the flowers lived exactly as long as they were supposed to, but not as long as the gardener expected them to.

When we plant something – tree or annual, we tend not to think about the plant dying. We are looking forward to its life and rightly so. Planting a plant is such an optimistic thing to do, so it seems very pessimistic to now remind you that it will die – eventually.

mustard - as an annual this plant will only live for a few months in my garden. It is flowering beautifully now attracting butterflies and bees, and then will set seed and die, making way for a new generation.

Mustard – as an annual this plant will only live for a few months in my garden. It is flowering beautifully now attracting butterflies and bees, and then will set seed and die, making way for a new generation.

 

Most gardeners who grow annuals do so knowing they are short lived and in the full knowledge that they will need to replace them at the end of the season. Although called “annual” they very rarely last an entire year. For many annuals, 8-10 months is extreme old age. Often we pull them out and replace them when they go to seed and start looking a bit ratty, rather than trying to care for them through their “old age”.

But even gardeners who are familiar with the short lifecycle of annuals often forget that other plants don’t last forever either. Often when we get a plant through its first year we tend to think of it as established and therefore there forever. Not so.

Most perennials tend to also have reasonably short lifespans – often only 3 to 5 years. If we are lucky, they will multiply for us. In this way the clump seems to live longer but each individual plant does not live any longer – it is just replacing itself as it goes. There is a lesson here for gardeners – replace our plants before they die. I find that fairly easy with most perennials – I simply split clumps or take cuttings so that I have more than 1 plant. By doing this every year or two, I have replaced the plant before it dies and often the passing of the original plant is barely noticed, as its offspring are happily filling its spot (and other spots) in the garden.

Salvia - this is an unusual variety of Salvia elegans with a purple tinge in the leaf and  magenta flowers. It is now over 2 years old and, as it finishes flowering, I will prune it and attempt to strike cuttings so that when the parent plant eventually goes, I will have plenty more and won't miss it.

Salvia – this is an unusual variety of Salvia elegans with a purple tinge in the leaf and magenta flowers. It is now over 2 years old and, as it finishes flowering, I will prune it and attempt to strike cuttings so that when the parent plant eventually goes, I will have plenty more and won’t miss it.

 

It doesn’t hurt to think this way about shrubs as well. Shrubs become woody with age, and although a good prune and a good feed will invigorate most old woody shrubs, it can only do so for so long, and the time will come when the shrub will simply not shoot back. By pruning the shrubs every few years and propagating cuttings, we ensure fresh new plants are available to assume its place as it ages. If seeds have come up under the shrub, or low branches have layered themselves, we may be lucky enough to have a “self replacing” shrub.

Many large woody shrubs can easily live for 20 years, or even more in good situations. Members of the rhododendron family can be very long lived and eventually some become more like small trees than large shrubs. This longevity makes it easy to see why we may not think about the shrub dying, and therefore why we may not recognise the signs of old age in the plant.

Indications of old age in a woody shrub often include reduced vigour so reduced flowering, less dense foliage as the plant becomes more woody and increased pest attacks. When we see this we usually respond with increased fertiliser and increased pest spraying. This extra effort may only give short lived returns for an old shrub, and it is likely to die soon anyway. Good care will most likely extend the life of the shrub, but not indefinitely, so if you are attached to it, now is the time to start thinking about its replacement – either buying a new one or propagating from it, so that the replacement has time to establish before the old plant finally kicks the bucket.

Just like old people and old animals, old plants become less vigorous and less resilient, so extra care can help make their old age more pleasant. If the shrub still has some good health, a hard prune may well be in order – followed by a good feed and water. A good feed for an old plant should be more than just fertiliser. If the plant has been there for a long while and largely neglected, the soil is probably somewhat depleted and adding fertiliser is a bit of a band-aid approach. The soil will also need a good boost of organic matter (compost) and possibly also a top up of minerals through trace elements or rock minerals. Fertiliser should be used in smaller doses. An old plant is less vigorous and that includes the root system which may not be able to take up the fertiliser as effectively as a more vigorous younger plant. The added organic matter will help the fertiliser stay in the soil and be available for the plant to take up slowly.

Plants which are past their prime will be more susceptible to waterlogging and drying out, and also to insect attack. This tends to make become them gradually more high care – a sure sign that the plant is ageing and it is time to think about the next generation.
All of the above also applies to trees.

Snow wood (Pararchidendron pruinosum) has been badly broken in the severe hail storm of 2014, however it is still very robust and the new growth is strong and healthy, there are many years still in this tree.

Snow wood (Pararchidendron pruinosum) has been badly broken in the severe hail storm of 2014, however it is still very robust and the new growth is strong and healthy, there are many years still in this tree.

 

When it comes to trees, we tend to think they will outlive us. Many certainly will. The saying that we do not plant a tree for our self, but for our children can be very true. Equally many trees will not last that long, and not because they were cut short, some simply do not have long lifespans. As a general rule, those that are slow growing and very large tend to be longer lived than those which are fast growing and not such giants.

We love to see and appreciate those ancient giants of trees and think of them as truly immortal, but alas they are not. In a dense forest old trees do die and fall over and that makes way for new trees to grow and take their place.

The beloved trees in our garden are also not immortal. Often we think because of their size they need nothing from us and that also is not true. Many an old miserable tree can be revived simply by a good feed and water. Good care can certainly extend the age of a tree considerably but not indefinitely, and the time will come when a new tree should be planted and given time to establish before the old one goes.

Many of the small trees we love in our gardens are not long lived trees – the grevilleas and acacias are a case in point. Ten to fifteen years is a typical life span for acacias and maybe 20 or so for some of the grevilleas. These trees are great for providing shelter while the garden gets established, but should not be relied upon forever – succession planning is important!

For those in the tropics and subtropics, the much loved Dombeya is also a sadly short lived tree (or large shrub), often only lasting around 10 years. This can be heartbreaking as they are not easy to replace and are so stunningly beautiful, we tend to become very attached to them.

Honey Gem grevillea - this poor old tree is being held by by blocks of wood, thanks to age and poor pruning when it was young. A new grevillea has been planted behind it as it will not last forever like this!

Honey Gem grevillea – this poor old tree is being held by by blocks of wood, thanks to age and poor pruning when it was young. A new grevillea has been planted behind it as it will not last forever like this!

 

I have recently planted a new grevillea beside my very gnarled old Grevillea ‘Honey Gem’, as I don’t know how many more storms the poor old thing has left in it, and I don’t want to end up with a large bare patch and no grevillea.

Rose of Sharon - this poor old shrub is on its last legs and it is time to let it go. It still provides some shelter for the garden below and is not dangerous so can stay a little while longer, plus the old branches are soft and make good homes for good bugs in the garden

Rose of Sharon – this poor old shrub is on its last legs and it is time to let it go. It still provides some shelter for the garden below and is not dangerous so can stay a little while longer, plus the old branches are soft and make good homes for good bugs in the garden

 

The Rose of Sharon hibiscus is lacking vigour and covered in mealy bugs – time to strike a cutting but being fast growing this will be easy to replace.

My native daphne (Phaleria clerodendron, a native rainforest tree) is also loosing vigour and looking less than its usual lovely self. So far I have had no luck with the seeds, but will keep trying, as I will keep trying to strike cuttings of my dombeya. These will both be very much missed when they inevitably go, and I would much prefer to have replacements ready before they do.

Tree waratah (planted by Jerry Coleby-Williams when Gardening Australia visited my garden recently!) will fill the space of the rose of sharon so that as it dies, a hole is not left in the garden - not for long at least!

Tree waratah (planted by Jerry Coleby-Williams when Gardening Australia visited my garden recently!) will fill the space of the rose of sharon so that as it dies, a hole is not left in the garden – not for long at least!

 

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Kate Wall

About Kate Wall

Kate has gardened since she was a child. Gardening as a profession came almost by accident - after volunteering to rescue flooded gardens and working in over 100 gardens, she felt her trial by flood had directed her to her true calling, and she has gardened professionally ever since. Kate is primary care giver to approximately 20 gardens concurrently (including her own), in addition to consulting, garden makeovers and creating new gardens. She lives and works in Brisbane, Queensland, and is passionate about gardening to suit our sub-tropical climate.

4 thoughts on “Every plant has a lifespan and needs care in old age

  1. Helen Young on said:

    Great post Kate, explaining some things that are rarely written about, but are really important. Life span is almost never explained on a plant label, and infrequently in books. Gardeners often blame themselves when plants die, not realising it’s just timing. Thanks.

  2. Clare bell on said:

    Hi Kate
    I garden and advise on the same principles as you do and I found your article very illuminating and wish all my gardening customers could read it- I tell
    them about the articles like this on Gardendrum in any case!
    I love to prune as this enables regeneration (in some cases), experimentation on my behalf to dare to test the boundaries of pruning and, if it fails, an opportunity to experiment with some other plant that takes my fancy!
    Cheers!

  3. Margaret Portell on said:

    Thank you for this lovely article. I’ve taken on a somewhat daunting project to rejuvenate an old straggly neglected hibiscus (not Rose of Sharon) in my neighbour’s garden. I’m sure it still has some life in it! I’ve already cut out a lot of the dead wood, still a long way to go. To be honest, I’m not being altogether altruistic as I don’t like looking at it over my fence. Should I use Seasol rather than fertiliser? How far back should I prune the living spindly branches?

  4. Many thanks for that useful article, Kate! You write about short-lived trees “This can be heartbreaking as they are … so stunningly beautiful, we tend to become very attached to them.” Yes, we can be very attached to plants and trees and be sad when they die. However, there is no “mourning” for gardeners, as stated by French gardener Pascal Cribier (who died recently):

    « Dans le jardin, il n’y a pas de deuil, c’est la chance des jardiniers  : ils se préoccupent de l’instant présent et pensent aux saisons futures. »

    Translation: In the garden there is no mourning, and that’s the gardeners’ luck: they are occupied by the present time and the thought of the seasons to come.

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