1 junE 2018
Regularly in the month of June a massive germination of willows is observed in, among other things, the cultures of pot and container cultures. This appearance of willows is caused by the fact that during this period of the year willows deliver a large number of seeds in the form of the recognizable white fluff.
Characteristic of willow seeds is that it must germinate within a few hours. If seeds have not found suitable germinating circumstances within 24 to 48 hours, the germination percentage decreases to nearly zero. For germination an open, moist potting soil is ideal. Especially freshly potted soil fully complies with this condition.
Appearance of willows can lead to capricious situations, with one batch of plants that has to do with willow seedlings and the other batch that remains clean. Although this one is also contaminated with willow seeds. The cause of this is the difference in moisture content on top of the pot between the different batches. When the seeds with fluff get on top of the pot, they will soon be no longer noticeable. Watering of the dryer batches e.g. one day later, probably will not give germination of the seeds because the seeds have already died. In case of contamination the seed can originate from trees that are up to a few kilometres from greenhouses or container field. In the Western European region there are at least 12 willow species. Usually it is the grey willow, crack willow or white willow. Depending on the weather conditions, this problem may not occur for a few years.