Most severe gardeners know the perfect practices surrounding alternating plant households in your soil yr to yr. What this implies is that crops with comparable traits — crops categorised inside the identical household (like dahlias and sunflowers) — cannot be planted in the identical plot in successive years as a result of they entice the identical pests and unfold the identical ailments, having a detrimental impression on the soil over time. Nonetheless, not as many individuals are as accustomed to the idea of allelopathy, significantly as a result of allelopathic properties aren’t constant throughout plant households. That’s, not all allelopathic crops are in the identical household, not all crops in a single household are allelopathic, and allelopathy might have an effect on some crops in a household however not others.
Within the case of sunflowers, they’re extraordinarily allelopathic, with each a part of the plant producing biochemicals able to suffocating or inhibiting the expansion of neighboring crops. Not every little thing is prone to those biochemicals – impatiens and marigolds are wonderful companion crops to sunflowers — however sadly, dahlias are. The allelopathic chemical compounds of sunflowers act as nearly a dahlia-specific herbicide, stopping the expansion of the usually plentiful and brilliantly numerous dahlia flower. Strive mixing your dahlias with zinnias or lilies as an alternative.