Your choice of mulch dramatically affects plant growth and yield!

Thursday, December 14, 2023

 This year we carried out demonstrations on 3 biodegradable mulches and 3 non-biodegradable mulches to see how they compare in a sweet potato production system here in Nova Scotia.

As horrible as this year turned out to be, it was the perfect year to trial plastic mulches as for many they made the difference between growing a marketable crop.. or not. Sweet potatoes are a challenging crop to grow in N.S, they need a long season with warm soils to produce tubers that make grade.

We demonstrated six different mulches, 3 biodegradable, and 3 nondegradable to test a variety of colours and thicknesses/material. There was a 30% difference in yields between the highest and lowest performers as well as differences in tuber grades (sizing) for each mulch. Before I talk about the treatments, it’s important to remember that this is not a replicated trial; the results highlight striking differences between mulches, but this is by no means conclusive.


-          Dubois, black, 1 mil embossed plastic (non-degradable)

-          Heartnut Grove, green, 1 mil (non-degradable)

-          Solar Shrink, black, 0.5 mil (non-degradable)

-          Film Organic “88”, black, 0.8 mil (biodegradable)

-          Dubois Bio360, black, 0.5 mil (biodegradable)

-          Dubois Bio360, clear, 0.5 mil (biodegradable)


-          3 rows, 400ft long, of each of each mulch was laid on June 13, 2023. Raised beds were 10" high, 28" wide.

-          Slips planted in late June. Management practices identical to rest of field (fertility, pesticides, etc)

-          12ft sections from each row were harvested Sept 19. Weighed for above and below ground biomass; tubers graded with a standard sizing board (<1.5”; 1.5” – 2.0”; 2.0” – 3.5”; >3.5”).


The table 1 below details specific results, with green highlighting showing the best performer in each category/column. Here are some brief takeaways:

-          The three non-degradable mulches produced the highest grade A (2” – 3.5”) tubers.

-          The green mulch produced the highest average weight per tuber (160 g) and stimulated root growth over shoot growth (root to shoot ratio).

-          The two Dubois biodegradable mulches were slightly too thin. The black 0.5 mil adequately controlled weeds but was severely degraded by September. The clear 0.5 mil had ruptured by July 20th and was overrun by weeds.

-          From these results I would recommend choosing a black biodegradable mulch no thinner than 0.6 mil and a clear biodegradable mulch no thinner than 0.8 mil.

-          We did not assess the cost difference between each mulch or consider the added cost of removing nondegradable mulches at the end of the season. These costs needed to be factored in to determine the profitability of using each mulch.

Table 1. results of mulch demonstration

    Please reach out to me at to discuss mulches, our results, or your plans for next year.