Perennial plants are generally known for being hardy (which makes sense, as they are perennial...), and if you purchase them from a reputable nursery, their establishment is almost guaranteed.
Therefore, it’s not particularly easy to fail at planting perennials. But rest assured, with a few appropriate actions, any reasonably skilled gardener can still almost certainly mess up their plantings.
Here is our reasoned guide, consisting of 6 lessons: follow it step by step, and you won’t be disappointed!
Lesson 1: Plant perennials at the wrong time.
It’s very easy to plant at the wrong time: just listen to your instinct and plant… when you feel like being outside, usually when the weather is nice in the garden: from June to September in the northern half, and over a slightly wider range in the south. The heat will weaken the young plants already stressed from moving from their cosy nursery.
Experienced gardeners, those who annoy us by succeeding at everything, plant hardy perennials from late September to November and from February to April. The more delicate ones, like Mediterranean varieties, are planted from March to early May: this way, they settle in gently, in cooler conditions, without thermal or water shock, making it almost impossible to fail.
During this time, as there is no visible vegetation, they perform the odd act of gently scratching the surface of the soil to check for a solid root stump beneath the surface and remove the clump from its pot to ensure it is well-rooted.
One alternative is to plant in mid-winter, from late December to mid-February. This method is much less reliable for failure: most perennials will survive, quietly dormant. However, if you choose a period of hard frost and somewhat fragile varieties, you still have a fair chance of successfully killing your plants if you’ve taken care not to mulch them.
Note: this winter planting method is rarely used, as it requires leaving the warmth of the fire to face the cold wind, and it demands certain tools to break through the frozen soil in the cold regions of the east, north, or mountainous areas: a pickaxe or jackhammer for occasional gardeners.
And if by chance you forget to follow this first lesson, you can still redeem yourself by neglecting to mark the planting spot: most perennials are non-persistent, making them invisible until late February or March; you will thus have the opportunity to give a good spade to the stump while turning over your flowerbed.
Summary of Lesson 1: to properly fail with perennials, plant them between late spring and early autumn.
Lesson 2: Plant perennials when they are in bloom (preferably forced).
Nature does things well: it’s just when they are in bloom that we want to plant perennials; and it’s just the time when it’s not good to plant them. This is therefore a very intuitive way to fail at planting: putting all their energy into blooming, these beauties tend to, like a proper fashion model, neglect their nourishment and live off their reserves. Weakened, they will struggle to settle in the garden.
If you make the wise choice to plant beautiful forced flowers from a heated greenhouse, such as those you find from March or April in many garden centres or shops, you significantly increase your chances of failure. Indeed, raised in cotton at 28°C, the plants will face thermal shock at the time of planting, which, if late frosts occur, are likely to be fatal. How can you recognise forced flowers, you may ask? It’s simple: they are not (at all) in bloom in the neighbouring gardens, and they are (a bit) too beautiful to be quite real.
Old experienced gardeners, remember, those who succeed at everything, have the annoying habit of planting empty clay pots (with dormant roots beneath the surface), purchased from good nurseries, and, as irritating as it is, it works.
But, we say this to console you, even they sometimes crack in front of those adorable bodybuilder plants from the local garden centre...
Takeaway from Lesson 2: to fail every time or almost, plant forced perennials that are in full bloom.
Lesson 3: Plant anywhere
A rose would look so lovely to brighten up that dark corner that never sees the sun… or a beautiful hosta in the dry rockery, it would create such a beautiful contrast with the cacti in the garden of the house in Saint Raphaël… Well done! Since roses love the sun and hostas prefer very cool soil, they will surely die.
Planting anywhere is the most effective method for failure: with rare exceptions, perennials have a defined biotope in terms of sunlight and soil type.
Follow your instinct, and don’t read the growing instructions provided on the label or care guide: exposure and soil type. Plant a heather soil plant in chalky soil, and it will disappear after having lamentably yellowed for a few months. Plant a fresh soil perennial (fresh soil is a well-drained, dark woodland soil that doesn’t dry out too much even in summer) in pure clay or in the gravel of a vineyard soil, and you’ll have roughly the same effect.
And if you want to prolong the plant’s agony, which can be a pleasant exercise in sadism with a clear conscience, add a small handful of suitable substrate, such as potting soil, to your unsuitable soil: the plant, delighted to find itself in familiar terrain, will start a lovely establishment… before hitting the hostile environment after a few days or weeks.
If you install a shade perennial in full sun, it will wait for the first heatwaves to die. And if you plant a sun perennial in the shade, there’s a risk it may not die. However, you will almost certainly prevent it from flowering properly.
If you are unfortunate enough to lack the instinct to fail (this can happen with long gardening practice), choose only varieties you don’t see thriving in the surrounding gardens. Opt for varieties admired during your travels in Morocco or Sweden, and plant them respectively in cool shade and dry sun….
Don’t laugh, we try every spring to dissuade Mediterranean customers from planting delicate Himalayan blue poppies they admired in the peat gardens of Scotland...
Remember this Lesson 3: the best approach is to buy randomly, based on the beauty of forced flowers, and forget about plants suited to the climate, soil type, and sunlight of the place where you will plant them.
Lesson 4: Do not respect planting distances
In general, plants are delivered with a maturity spread indication: for example, ←→ at 40 cm
This means that the spread of the plant, in time, will be about 40 cm, and therefore, to achieve a dense mass, they should be planted about 20 cm apart.
To properly fail, do not respect the distances recommended by your nursery. Pack the clumps tightly against each other; this will create a very nice effect at planting… and will ultimately kill a good portion of your plants that will be too busy fighting each other to have time to grow. Indirect effect: your partner or other heir may have a fit when calculating the price per square metre of your flowerbed... But, I admit, this can be a pleasant side effect at times.
You can also, to save money, space the plantings excessively. This will look ugly, but in itself won’t kill your perennials, which will be comfortable. So, note this tip: just let the adventive plants grow, as the knowledgeable folks say: in simple terms, the weeds. They will feel right at home in a terrain that suits them perfectly and will quickly smother the intruders in a form of nationalism tinged with xenophobia, especially the first spring. Once your perennial is established, it will become part of the landscape and be respected by the local flora. Those of us with Italian ancestors know what we’re talking about…
Don’t forget Lesson 4: to fail with your perennials, plant very densely or, for those on a budget, let the weeds smother your well-spaced young plants.
Lesson 5: Don’t bother with planting
The advantage with perennials is that pots are generally small; so it’s just a matter of making a small hole, which isn’t too tiring. And then, if you really underestimated, just push a bit to fit the clump in. And there you go, never mind if it sticks out a bit!
Experienced gardeners, we need not introduce them, claim that you should make a hole three times the width of the pot and twice its height, and even a bit more for varieties with large or tap roots, so that the plant can push its young roots into soft soil. For the same reason, they damage the plant intentionally by gently undoing the root ball (the roots that on some varieties wrap around the edges and bottom of the pot, leaving the top of the clump flush with the soil or covered by a few millimetres of soil).
An alternative for those who are unfortunate enough not to have a garden to fail in: plant a plant with a strong root development in a small pot. How to recognise them? Generally, they are the tallest at maturity.
Summary of Lesson 5: make a very small planting hole and push hard if the clump doesn’t fit.
Lesson 6: Neglect watering
We really like this method, as it is spontaneous: you just have to do nothing to apply it. We have practiced it a lot, and still use it occasionally, even if the rather rainy nature of our Flanders complicates it a bit.
Let’s explain: a plant without water dies. For a cactus, this can take several years. But for most varieties in our regions, it’s enough to forget the pot before planting for a week in the sun to cause serious damage or to neglect watering in the weeks following planting, especially if it’s hot.
So don’t do like the old gardeners, who after removing the clump from the pot, soak it for a few minutes in water, and then pour a few good litres of water on the freshly planted plant even when the soil is moist.
Note, this method has a near 100% success rate at the time of planting, as all perennials, even those for dry soil, need water at planting. However, the method becomes very uncertain afterwards: once the plant is well-rooted, after 3 to 6 months, it will be difficult to make it die of thirst (unless you planted it in the wrong place, see Lesson 3): once its root system is developed, it will resist your negligence by seeking its water deeper.
An interesting variant for very watered areas is drowning: except for water’s edge plants, equipped for a big bath, perennials do not like having roots permanently submerged in completely soaked soil. This is particularly true for well-drained soil plants (soil that doesn’t retain water, where there’s never a puddle even after a heavy storm, often stony, sandy, or very light), which will die suffocated under very regular and substantial watering in heavy soil. This is a technique that requires more effort, as you need to think about watering very often and a lot to really drown a plant, which is hardly practicable in a Mediterranean climate. However, it works like the icing on the cake if you have properly followed Lessons 3 and 5 in a rainy region, heavy soil, by ensuring to plant in a hollow to create a small pool.
Lesson 6 is simple: forget watering… or drown your plant.
In conclusion
If you reasonably apply at least half of these tips, especially those regarding planting and watering, you should succeed in making the majority of your plantings disappear within a few months.
And a note for the pessimistic minds who will shrug at these “obvious” anti-tips: are they really sure they have always planted the right plant in the right place at a reasonably favourable time, with appropriate watering? Let them come forward; we’ll hire them. Immediately!
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