Naturally, the main, and most straightforward way to see if your substrate supports your needs is by checking the performance of your plants. If you are entirely happy with the growth, health, and yield of your crops, it likely is a near-perfect match. However, when you’re not entirely satisfied, there are a couple of characteristics of the substrate that you might want to investigate. Let’s take a look and make sure that the substrate matches your needs.
The porosity of a substrate
The first thing we’re going to investigate is the porosity of the mix. The porosity tells you more about the ratio of “open” pores to the total volume of the substrate. Simply put it tells you how much space for air and moisture is available within the substrate. This characteristic is largely determined by the distribution of different pore sizes within the mix. The distribution of larger and smaller substrate particles throughout the mix correlates to the distribution of pores.
If the mixture has little porosity, it has little space to store air and water within the substrate, which generally isn’t helpful to your crop. If the substrate offers high porosity the roots are provided with larger amounts of water and air, benefiting most nutritional, and growth processes.
All of this is closely related to the coarseness of the mix. Read more about this property in this related article.
Uptake of water
The second topic worth investigating is how water behaves within the substrate. Does the substrate take up irrigation water easily? In other words, is the re-wettability on a good level? If you’re struggling with that, you might want to take take a look at this article about wetting agents.
Then it’s also good to know how water flows to the roots of your plants. Small pores within the substrate typically fill with water (due to capillarity). This in turn means that it will cost your plants energy to get that water out of these pores, into their roots.
Then, thirdly, try to keep in mind that the exact same substrate mixture performs differently in differently-sized containers. The water and air ratio for example doesn’t stay the same in every container size. Not even when you take great care to fill the pots correctly because the size of the container itself influences the pore-size distribution that we’ve investigated earlier in this article.
External factors: your nursery and methods
Finally, you should also always keep the circumstances at your nursery in mind. These matter when evaluating the performance of a substrate mixture. Your irrigation methods, the climate zone, your type of controlled (or less controlled) growing environment and your feed schedule are all influencing factors that can be supported with the right type of substrate, or that can influence the performance of your substrate.
Make sure to discuss the details of your cultivation methods with your Kekkilä Professional distributor. Together you can find the substrate that matches your needs.