An Alternative Method of Rooting Oleander Cuttings

The experiments with this method apply to regions with cold winters; that is, where oleanders are grown in pots, not the Mediterranean area or the southern USA (although of course this method can be used there as well). 


Premise and Questions.

It's said that it's best to take cuttings in the spring. That is when the plant is at its most vigorous - the sap is flowing after the winter rest period and the cuttings root most easily. This is correct. However, for the "oleander gardener", it is the wrong time. The plants need to be pruned in late autumn or the beginning of winter. The available space in the overwintering location is always too cramped; therefore the mass of foliage should be reduced and the branches cut back. This also allows the plant to be tied up more easily; diseases and pests are easier to combat. 
In the spring, there is already enough to do: moving the oleanders out of their winter quarters, acclimatizing them once again to light, fresh air, and sun - especially if one has a lot of plants. So why not postpone rooting cuttings until the winter months? 
If one inserts cuttings, individually or several together, into soil (the correct soil mixture, which is as sterile as possible), one has no way of checking the rooting progress. Some cuttings will sprout, obviously developing roots; others dry out above the soil and rot beneath the soil surface, contaminating still others.    

If cuttings are placed in water (with or without covering, according to the amount and the effort expended), one does indeed see the progress of the rooting process; but then, if several cuttings have been placed together in one container, one soon has to deal with the inevitable tangle of roots, mixed up with the failed (rotting) cuttings.  

The basic thought: Propagation by cuttings should be undertaken at the time of year when the mother plants are resting in their overwintering location. 


Moisture, Warmth, Darkness.

What does a cutting need in order to root well, quickly, and as reliably as possible?
Moisture. This means a humid atmosphere, that is, air which is as moist as possible. If the cutting is located in a humid atmosphere only and not in a wet medium (water), it has less contact with its surrounding environment and can be kept more sterile. 
Warmth. 25 - 30 degrees C (78 - 87 F) is optimal for stimulating the formation of roots. the temperature should be kept as constant as possible.  Depending on the number of cuttings, this could mean anything from a warm propagating box to an incubator. In our case, the location was in the boiler room where the central heating is located, and in practice the temperature fluctuated between 20 and 30 degrees C (69-87 F). 
Darkness. A cutting planted in soil also has darkness; the root area lies in darkness. In practice, a cutting placed in constant darkness tends to form roots along its entire length. However, if the cuttings now and then receive a bit of light and through the moisture source, they'll know very quickly where they should form roots - namely, at the lower end. 
In short, this means: "Rooting under controlled conditions, independent of the season".   

No rooting aid (rooting hormone) was used. 


The  Method.

The method, easy to apply even for a large number of cuttings, involves rooting in test tubes. Under these conditions, one can check precisely what is happening throughout the entire process, and it does not depend on the time of year. 


Test tubes measuring 100x20mm are used.  Styrofoam blocks with corresponding holes were used as bases to hold them.  For a mosture-retaining medium, perlite is used, and specifically absorbent agro-perlite, not the water-repellant perlite used for insulation purposes. 

A small amount of perlite is placed in the test tubes; this is moistened (optimally with an injection syringe or a pipette), then the cuttings are placed into them individually. The perlite supplies a moist atmosphere within the test tube; a covering "bonnet" insures that the cuttings sprouting outside of the tubes have enough moisture in the air to keep from drying out.  

Cuttings of Splendens Giganteum are known to be easy to root.

Cuttings of Petite Salmon are rather difficult to root.