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Using Worm Casts

Updated: Mar 8, 2022

When you read our #indoorplantcaretips it is hard to miss the fact that we are fairly keen on worm casts. This is because they provide an #organic supply of micro-nutrients to #indoorplants without risking a build up of salts or root 'burn' which can result from using other types of plant food.

What are they?

Worm castings are the end product of worms digesting soil. The result is a rich source of micro-nutrients which are small enough to be dissolved in water & hence are accessible to your plants. If your plant was growing in the wild it would be part of a wider ecosystem & would therefore have independent access to these nutrients through its root system. Growing in a pot it is isolated & therefore entirely dependent on you to feed it.

How much should I use & when?

Plants need access to food when they are growing. Most of their energy comes from sunlight & water which they combine to create carbohydrates. However they need other nutrients in minute quantities to build & repair cells. One way of providing this to them is to #topdress your pots in spring. How much you put on will depend on what kind of plant.

For a #fastgrowingindoorplant like a lightly variegated #pothos such as #scindapsusepipremnumaureum (#DevilsIvy) a #Monstera or a #Syngonium 25mm of worm castings will provide up to 6 months of food. As you water from the top the casts will, over time, dissolve into that water thus feeding your plants. With a highly #variegated #cultivar (a nursery selected plant) which are generally slower growing a thinner layer is better. An example of this is #epipremnumpinnatummarblequeen .

For #slowgrowing plants or those adapted to harsh or arid conditions a more meagre diet is needed. Over feeding is harmful to your plants & although the risk of salt build up in your growing medium is reduced it is always best to attempt to emulate a plants natural environment as close as you can. Indoor plants which come into this category include succulents like #Seneciorowleyanus (or as it is now #curiorowleyanus) but also many epiphytes such as #hoyas *

As well as using #wormcasts directly as a #topdressing you can also use them to make a #composttea. Use around 6 heaped table spoons to 750 ml of water & let it stand over night. This gives you the flexibility of feeding plants throughout the growing season every time you water. Dilute to a third for #succulents

A final note of caution ...

We joke that the first rule of #plantyhaus is that there is no such thing as a #houseplant & that our only real care advice is that 'it depends'. The latter is getting more & more true. In times gone by indoor plants in the Western Hemisphere all but stopped growing in the winter & so you stopped feeding them. However, of late, in warmer midwinter times, some of ours don't stop. So just keep your eye on them & be prepared to adapt your care regime in the light of the evidence in front of your eyes. Generally speaking, your plant will tell you what it needs or dies trying :)

* of which we currently have some stunning specimens Easy Care Plants | Planty Haus)

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