Month: September 2013

When talking about how to grow a certain succulent, the question asked most often is : “How much water does it need”. Unfortunately this is also the question which is the most difficult to answer, because of the numerous factors involved.
The following remarks are intended to give you some general background information in order to point you in the right direction:
__ More succulents die from too much than from too little water
__ Lack of water is much more easily remedied than too much of it
__ A small plant has less substance than a big one and therefore dries out more easily. For that reason young seedlings should always be kept slightly damp
__ The more leafy a plant is the more water it generally needs
__ The fatter the leaves and/or stems are, the better the plant is able to withstand drought. The same applies to the presence of wax layers, hairs etc.
__The larger the pot, the longer the soil will stay wet
__ At lower temperatures the soil will stay wet longer
__ Plants that even during the growing period tolerate little water, are best given a small pot and an extra porous soil
__ Many plants show when they want to be watered again after their resting period, e.g. by forming new leaves (also see next remark)
__ If you don’t know the growing period of a plant it is best to proceed as follows: Every few weeks mist the plant and see how it responds (if at all). If it shows signs of renewed growth, start watering carefully. if nothing happens after the misting, repeat this a few weeks later
__  Allow the soil to dry out before watering again
__ WHEN IN DOUBT DON’T WATER

To be continued.

As soon as we take plants into cultivation, we- by definition- change their environment. When we grow them in the open, we may change the amount of water they receive and the period in which this happens, the quantity and quality of the nutrients; we may take measures to protect them against bugs and other animals, diminish competition from other plants; we may also change the alkalinity of the soil, the influence of wind and sunshine, the slope of the plot and so on and so forth.
If we go one big step further and bring the plants into a controlled environment like a greenhouse, we can influence even more factors.
With or without human intervention, the way a plants responds to its environment is subject to 3 ecological laws.
The first one is known as the law of limiting factors: if any factor reaches a certain minimum, this diminishes the plant’s potential and cannot be compensated for by other factors. Let’s say your plant does not grow well because the soil  contains far too little nitrogen. However much phosphate or potassium you add, this will do nothing to get the plant growing well again.
The second one may be called the law of compensating factors: as long as the minimum is not reached, other factors can partly compensate for a deficit. This explains the fact that certain shade-loving plants will happily grow in sunny open places, as long as the air is very humid, as is the case near the sea or next to a waterfall.
In cultivating plants, the combination of these two laws means that:
A.  (most) plants will grow reasonably well even if not all growing factors have reached their optimum.
B. the more factors do reach their optimum, the less influence unfavourable factors will have.
We should also keep in mind that each species has its own minimum, optimum and maximum with respect to all external influences, and that some species are much more tolerant than others. Under natural circumstances one encounters the phenomenon that certain species occur “everywhere” and others only in very special situations. In cultivation this is reflected in the fact that some species are “easy” and others “difficult”.
The third law only applies to cultivated plants and partly contradicts the first 2 laws.
I call it the law of equilibrium: for a successful cultivation, there must be a certain balance between the three factors water, light and temperature. Because of that the following lines may be read from left to right as well as vice versa.

more water necessitates more light and more heat
more light necessitates more water and more heat
more heat necessitates more light and more water

less water necessitates less light and less heat
less light necessitates less water  and less heat
less heat necessitates less light and less water

This means that if a lot of water and heat is supplied, the plants must also get a lot of light.
When plants are kept dry because it is their resting period, they need less heat and light.
Once you understand the principle you can figure out other combinations for yourself.

To be continued.

 

Many years ago, when I ran a nursery in Holland, I was often asked by clients how a certain plant had to be cultivated.
Of course I could have answered that question along the lines of a colleague of mine whom I sometimes met at a trade fair in Germany. A potential client would ask him if one of the plants on display would do well in a shady spot. The answer would be something like: “Yes of course madam, you could not find a better plant for a shady spot than this one” .  Usually this was enough recommendation to sell the plant and when the happy client had moved on, a new specimen of the same species was put on the table. Before long, another person would ask him what kind of plant that was and if it was suitable for a very sunny spot in the greenhouse. And the answer was -you have already guessed it- that no plant was better equipped to cope with a lot of sun than this one.
It was quite hilarious to witness this kind of conversation, but it was also embarrassing because at least half of these plants would not stand a chance to survive for more than a few weeks.   Luckily for the seller, this fair was only once a year and the chances of running into a client dissatisfied by last years’ advise were minimal.
Still, apart from the fact that this not a nice way to treat people (and plants),  I considered it to be bad business practice.
To return to the opening sentence, giving useful advise is difficult, especially when the buyer is new to the hobby and therefore has difficulty understanding and remembering all the various aspects involved.  After a while I decided to put together a cultivation guide covering as far as possible all the different factors: how much water to give and when, what the minimum temperature should be in winter, how much light was advisable etc., etc.
Like in other situations, just applying a set of rules, without knowing and understanding the basic principles, does not lead to the best possible results.
In the next post I will therefore discuss some of these principles.