The perfect seedling substrates. Chapter1 - White and Black peat.

In this series of article, I am going to cover basic information about?? seedling substrate types, and how to choose the perfect one for your needs. Substrate consists of mixture from white and black peat, which are available at different fractions, furthermore mixed together with limestone to adjust the pH, wetting agent and ??fertilizers.

So, let’s break it down one by one to understand what kind of difference each of it provides. Today we are going to review the peat types. Other articles will follow, so don’t worry if you didn’t get the full picture right away.

White and black peat.

Every peat field has both of these. White peat is usually on the surface of peat field, and the deeper you ?? harvest, the darker the peat gets. It also varies ??geographically because different countries have different sphagnum species. For example, Ireland has darker peat in general, therefore their peat is more popular for ??mushroom casing soil, because for mushrooms ??moisture holding capacity is the priority number one.

Advantage of white peat is that it provides a lot of ???air porosity and drainage in the substrate. If the substrate consists of just black peat, the roots will simply get rotten due to the lack of air.

On the other hand, black peat has the opposite that plants need – it can hold much more water comparing to the white peat and it dries out much slower. And in the seed sprouting phase that is actually more important factor. But black peat also weighs a lot more which is a disadvantage for multiple reasons. The plastic packaging used for peat cannot hold such a heavy weight. The bags and bales simply won’t hold such weight. They will break. Adding lots of plastic just to hold the weight makes the black peat even more expensive. Also, the ??container cannot be overloaded in terms of weight because ?? trucks simply are not allowed to carry such weight on the ???roads.

All these factors considered; the peat types have always been mixed together in different proportions depending on the ??climate conditions where the peat will be used, road weight limits etc. In countries which have very ??hot climate, black peat is more preferable, otherwise it needs to be watered a lot. And watering the soil too much causes the valuable NPK to be washed away from the soil.

However, there is one peat mixture that is the most popular of all for the ?? seed trays. It’s not necessarily the best, but let’s just say it’s the most used one because how cost effective it is. It’s approximately 80% white peat and 20% black peat (number may vary a little). This proportion makes the MIX possible to be packed in 250L and 300L bags. For these bag types more black peat cannot be added due to weight. Also, this weight per container in many cases might reach the maximum road weight limits.

The second most popular mixture is 70% black peat and 30% white peat. You might wonder – why such a difference all of a sudden? The reason is very similar – this is the maximum weight that bags of 70L and 50L can hold. This is certainly better substrate for seed trays, but smaller packing is much more ??expensive and might exceed road weight in some countries. But for some plants it just pays off since they have higher requirements, or in some countries access to water is limited etc.

So, there you go – we have reviewed the basics of first chapter, which is peat proportions. Feel free to ask any questions, or share information how is it in your country!

Many more articles will follow.