Simple solutions are in demand

Three news stories from the recent past illustrate the attention that the topic of peat reduction is receiving from the public:

• In September 2018, a peatland in Emsland burned - the column of smoke could even be seen from space - and caused huge CO 2 emissions.
• By the end of 2020, the last peat-only power plant was online in Ireland, which has since phased out peat production.
• "Planting with peat is like heating with coal," German Agriculture Minister Cem Özdemir put it in spring 2022.

Peat use has a significant impact on the climate. The draining of peatlands and the extraction of peat emit large amounts of CO 2 in a short time, so the use of peat-based soils contributes to global warming. In Germany, therefore, the use of peat in commercial horticulture is to be largely reduced by 2030, and in the hobby sector it is to be ended as early as 2026.

In this context, a wide range of research is underway into substitutes, production processes and methods of use. In the meantime, nurseries can handle peat-reduced or even peat-free substrates quite well and are adapting fertilization and irrigation strategies.

In the hobby sector, on the other hand, there is still comparatively little knowledge about consumer attitudes, purchasing behavior and functionality in use with peat-free substrates or potting soils. In this context, consumers are just as crucial for a successful system change as producers.

If peat-free potting soil does not provide a good supply of nutrients or if potted plants cannot be watered well in peat-free potting soil, this can lead to earlier plant death and dissatisfaction among customers.

Consumers know little about potting soils

And what role does the change in appearance of peat-free potting soil play? It is possible that the lighter appearance of wood fiber- or coco-based substrates is less attractive for use on balconies and in flower beds than one made from darker peat, leading to reluctance to buy.

Geisenheim University of Applied Sciences conducted an online consumer study in December 2021. For this, more than 1,000 people from different age groups and all German states were surveyed, so the composition of the sample is very similar to that of the adult population in Germany.

The survey shows that potting soil is basically a product that is bought rather rarely compared to other consumer articles. Only just under 12% of respondents buy potting soil more than twice a year, while almost 40% never do so or only every few years. The purchase frequency of potted plants is significantly higher. In a previous study from the summer of 2018, more than 80% of respondents said they had purchased an ornamental plant in the last quarter, and a third had done so within the last week.

About one in four people have already purchased peat-free potting soil in a bag, and one in six have also purchased a potted plant in peat-free potting soil. But more than a third of those surveyed do not know whether they have ever bought peat-free potting soil.

When buying potting soil, the price, instructions for use, nutrient content and substrate composition are particularly decisive factors. For two-thirds of respondents, price is rather important to very important (top 3 levels on a scale of 7). 58% of the study participants attribute this importance to the composition of the substrate in terms of peat and substitutes. The substrate color, which is, after all, dependent on the composition, is important for only 43 % of consumers.

When the color of potting soil is explained

The color appeal of potting soil was also tested in an experiment (Figure 1).

For this purpose, all respondents were first asked to state their purchase intention regarding light or dark potting soil. For this purpose, they were shown pictures without further explanation. The dark soil achieved a significantly higher purchase approval than the light soil.

The sample was then divided into groups, each of which was shown the pictures again, but now with further information. One group was told what type of potting soil it was, namely peat-free potting soil made from wood fiber (light) or potting soil made from peat (dark). Again, the purchase intention for the dark peat potting soil was higher, although not as strong.

In other groups, respondents were given statements about the environmental impact, namely that the production and use of peat-free potting soil produces significantly less greenhouse gas emissions than that with peat. The purchase of peat-free potting soil therefore meant environmental protection, whereas the purchase of peat soil promoted environmental destruction. The purchase intention then changed in favor of the light-colored, peat-free potting soil. It did not matter whether the respondents were confronted with statements on environmental protection (positive statement) or environmental destruction (negative statement).

Nutrient supply and water balance must function

The peat-free potting soil purchased is mostly used for planting in tubs or balcony boxes. 68% of the respondents named this purpose. In addition, the substrate is also used by 62 % of consumers for potting individual plants. In such containers, the root space is rather small, so that nutrient supply and water balance must function well. Only 19 % of hobby gardeners also use the potting soil for beds or graves, so that the application in the area - where the substrate color may play an aesthetic role - is not so significant.

Consumer experiences with peat-free potting soil are predominantly positive. Almost three quarters of respondents rated it as rather good to very good (top 3 levels on a 7-point scale).

When asked what had not worked out so well during use, 52 % of consumers said that everything had actually worked out well. Only just under 18% each mentioned problems with watering and poorer plant growth, followed by difficulties with fertilization and mold infestation of the substrate with around 15% each.

These positive findings on consumer experience are contrasted by questionable findings on consumer knowledge. The statement "I know quite a lot about potting soil" met with only 17% agreement (top 3 levels on a 7-point scale). This subjective assessment was compared with an objective knowledge test in which the study participants were asked to assess six different claims about potting soil (Figure 2). Only just under a third of the respondents had correctly assessed more than half of the statements. And the proportion of those who did not know the answer to these questions averaged almost 38 %.

Precise information and ease of use needed

The following findings emerge from the research:

• Potting soil is mainly used in pots, boxes and tubs. Spreading in the field is less common.
• Substrate color no longer plays a role when potting soil ingredients and their environmental impact are well informed.
• Subjective and objective knowledge about potting soil is quite low, but conscious experience with peat-free potting soil is quite good. However, because almost half of the respondents named problems with its use, deeper insights should be gathered on this in practical studies (e.g. observational studies during use).
• Potting soil is a so-called low-involvement product. It is rarely purchased and consumers bring little knowledge and interest in the product. Therefore, product information regarding environmental impact must be very precise and use must be trouble-free and reliable.

The authors work at the Chair of Horticultural Economics at Geisenheim University. One of the research foci is the sustainable consumption of horticultural products.