Want to grow weed in soil? This starts with choosing a good soil. You cannot just open up any bag of garden soil and put your weed plant in it. It is more complicated than that. Can you use universal potting soil for weed, for example? What is a good soil enhancer? What about seedlings and when should you transplant weed? In this article we will tell you all about the best potting soil for weed!

In this article:

Types of potting soil for Weed

There are many different kinds of potting soil for weed. The most common type is, of course, earth. Growing weed in earth is traditional, relatively easy and effective. You can also choose hydroponics or hydro growing. You can do this with stone wool, coconut fibres or hydro granules as a medium. Each medium has its own advantages.

In this article we look at the best potting soil for weed if you want to grow in soil. Would you like to know more about hydro growing on rock wool, coconut fibre or hydro granules? Then check out our blog “growing weed on coconut?”.

What characteristics should potting soil for weed comply with?

There are many different types of soil. Not all of them are suitable for growing weed, as a number of factors are very important. The most common types of potting soil when growing weed are earth, coconut fibre, hydro granules and rock wool. They are all different and each medium has its advantages. Yet they all have a number of things in common. These are the characteristics that potting soil for weed must comply with:

Structure of the soil

A weed plant and her roots need sufficient space to grow. Therefore the soil structure is very important when growing weed. A structure that is too firm can prevent the root system from developing properly because there is little oxygen available to the roots. That is why a loose structure is preferred, in which roots can grow freely and are constantly supplied with oxygen.


This may not have much to do with the composition of the soil, but it is certainly important. The amount of potting soil you use affects the size of your weed plant. A weed plant needs enough space to grow. We recommend that you always use more than 5 litres of potting soil for weed. The best is 12 litres or more. With this volume your weed plant will have enough space to reach its maximum plant height. The maximum height depends on the strain.

Water retention & Drainage

This may sound contradictory. But good potting soil for weed must be able to both retain and drain water. This ability to retain water is called water retention. This ensures that the soil can hold the water and nutrition you give your weed plant. This prevents the plant from drying out. The removal of water is called drainage. Without good drainage the water stays at the bottom of the pot, making the soil too damp and therefore blocking fresh air. This increases the chance of bad moulds and dying roots. You ensure good drainage by making holes at the bottom of the pot so that the water can drain away. A loose soil structure is also very important.

Large pots with holes in the sides for drainage.


The pH-value indicates the degree of acidity of the soil. Nutrients can only be absorbed by a weed plant if the acidity level in the soil is favourable. That is why you want to create a stable pH-value, so that your weed plant can always take maximum advantage of the nutrients from the soil or the nutrition you give it. In reality this means that the water you give your weed plant must have a good pH-value, so that the acidity of the soil remains optimal. With soil the ideal pH-value is between 6.0 and 6.5. With hydro cultivation (rock wool, coconut or hydro granules) between 5.8 and 6.0.


Your weed plant needs nutrients to grow and flower. Potting soil for weed must therefore contain enough nutrients. When you buy universal potting soil for weed, it usually contains enough nutrients for the first 4 to 6 weeks of growing. By the time your weed plant has reached flowering this buffer is depleted and it needs extra nutrients. Therefore we recommend every grower to give extra nutrients to the plant by mixing plant nutrition into the water.

In the first two weeks of growing - when your weed plant is still a seedling - you do not want too many nutrients in the soil. Read more about this under the section “Seedling and Transplanting”.

Growing weed in earth

Traditionally, we grow weed in earth. But why? Growing weed in earth requires relatively little knowledge compared to hydroponics or hydro growing. Simply because it is the natural way of growing weed. Moreover, a weed plant in earth indicates in a gentle manner when something is wrong. Earth is the most forgiving. It is okay to make a mistake when growing weed in earth. And perhaps even more important: you have enough time to recognize the problem and solve it. 

With other mediums such as hydro granules it is different. Do you leave your weed plant dry for too long or make some other mistake? Then your plant can quickly die. Is your weed plant standing in earth? Then she has a buffer, so to speak, which allows her to take a few blows before she dies. Another important advantage is the taste of weed. When your weed is grown in earth or another organic medium, the taste of the end product is said to be better and fuller than when growing hydro.

Healthy weed plant in soil.

Growing weed in earth is relatively easy. If you know the basic rules, you can grow weed in earth yourself. But what is the best earth for weed? What is the best potting soil for weed to buy? Do you have to prepare the soil yourself? You have several options. For beginners we recommend the use of universal potting soil for weed.

Universal Potting Soil for Weed

Universal potting soil is ideal for weed because it contains nutrients, but not too much. This gives your weed plant a good buffer to get through the first four to six weeks of growing. When the nutrients are nearly all used up, you can start using special plant nutrition for weed. With universal potting soil you can also choose to give extra growth nutrients or a root stimulator during the growth phase. Do you choose soil with extra nutrients? Then over-fertilization (too much food) is a real possibility, resulting in unhealthy leaf problems.

When you buy potting soil with extra nutrients then this often contains general plant food. This is generally not ideal for weed plants. It is therefore better to supplement the amount of nutrients yourself with special weed nutrients from Plagron or BAC. This way you will get more out of your soil and you do not need to look for extra rich potting soil.

Seedling and Transplanting weed 

Potting soil for weed ideally contains a lot of nutrients. But there is a downside. You do not want a seedling to grow in a soil with lots of nutrients. In the first two weeks of growing (the seedling phase) the plant is not yet big and strong enough to handle a large amount of nutrients. So it is best to let your seedling grow in special sowing or seedling soil. This contains less nutrients. An ideal product that can help you is the Spongepot. These small blocks of earth are perfect for seedlings. After you have let a weed seed germinate you put it in a piece of Spongepot. In a little time you have a healthy seedling that is ready to keep growing in a richer soil.

Sowing or seedling soil is the best choice, but it is not necessary. Your seedling will probably also do well in universal potting soil for weed. However, do not use potting soil with extra nutrients. This is not suitable for your seedling.

A full-grown seedling - from this moment on you can transplant weed.

Transplanting Weed

Are you going to grow your seedling in sowing or seedling soil? Then you can use a small pot, since seedlings do not need much space. It is important, however, that you put your weed plant in a large pot when the time comes. The larger pot should be filled with weed soil that is much richer in nutrients. Transplanting weed is very easy. You just have to know the right moment.

If you use cubes of sowing or seedling soil like the Spongepot, then you can tell it is time to transplant when roots appear. If you are using a small pot and you can't see the roots, we advise you to wait until there are 4 leaves on the weed plant. This usually takes 1 to 2 weeks. Then you can transplant the weed into a larger pot. Do not wait too long with this. If the roots do not get enough space and start to grow together, this will have a negative effect on the growth of your plant.

Make your own potting soil with a soil enhancer

Do you want to get the best potting soil for weed? You can choose to buy special potting soil from brands such as Plagron. However, you can also make the best potting soil for weed yourself by using a soil enhancer and universal potting soil! It is very simple and relatively cheap. You can choose from various soil enhancers such as Plagron Supermix, BAC Funky Fungi or BAC Bio Tablets.

The word says it all: with a soil enhancer you can improve the quality of your potting soil for weed. Soil enhancers contain all sorts of natural fertilizers that ensure a rich soil life and better resistance for your weed plant. Soil enhancers usually contain all sorts of moulds, bacteria, vitamins, minerals and spores. BAC Funky Fungi mainly contains moulds, including four special types of mycorrhiza. These are fungal roots that search for water and minerals underground and then pass them on to your weed plant. These helpful fungi make the life of your weed plant a lot easier; they make each other stronger. Soil enhancers mainly promote the growth of the root system and ensure that nutrients from the soil can be optimally absorbed by the weed plant. In other words: a rock-solid foundation!

Soil enhancers usually come in powder that you can mix through the soil or tablets that you can dissolve in the soil. Super simple! Mix a soil enhancer with universal potting soil. As soon as your seedling has grown in seedling soil, put it in this optimal weed soil mix. You have now created the best potting soil for weed. It now contains enough nutrients for the entire grow. You can combine soil improvers with a growth stimulator or flowering stimulator for the best result!

The best potting soil for weed is made with a soil enhancer!

Other Natural Soil Enhancers

In addition to soil enhancers, you can also use other natural soil enhancers. Take perlite, vermiculite and worm compost, for example. These nutrient-rich additives do an excellent job as an addition to the soil. 

Perlite is a very well-known one. These are the white grains you often see in bags of potting soil or garden soil. Perlite provides a more airy soil and good drainage, but it also helps the soil to retain water. Worm compost contains all sorts of microbes that are useful during the growth phase of the weed plant and they ensure a better soil structure and water retention. Vermiculite is similar to Perlite, but is mostly used when you want a looser soil structure. Never use too much of these natural soil enhancers. Excessive use can cause your medium to become too airy or to retain too much water.

Want to know everything about growing weed on coconut? Click on the link for an extensive article on hydroponic growing on coconut fibre. Do you still have questions about the best potting soil for weed? Do not hesitate to contact our customer service.