Soil and Drainage:
A good foundation
Proper Soil and Drainage is a MUST!!
The key to a successful Japanese Miniature Garden is the soil and how well it drains. This creates the foundation for your garden. If you are creating your mini garden in a trough, angle the trough towards to drainage holes, and cover the holes with broken chine or earthenware large enough so they do not fall through the holes. Create a layer of pebbles or washed gravel at the bottom of the trough, make sure to avoid any material that hold water.
Soil:
Start by placing peat, moss, or a leaf mould over the drainage layer, you can also use dead leaves or old turf as a cheaper means. Check all materials before you place them in the container, and remove any roots larvae, twigs seeds or insects of any kind before placement. Press this layer firmly into the trough so that all corners and edges are well packed in. This layer works to keep the soil at the desired level of moistures, and prevent soil from being washed away during watering.
Suiting the Soil to the Plant:
Often plants have different needs, making the soil that works for one plant unsuitable for another plant. Soil is also affected by various factors. Lime loving plants go well with chalky soil, like rock and alpine plants. Acidic sandy soil is best for corn and bulb plants, heathers, and flowering shrubs. Shrubs and moisture loving plants prefer a peat soil. Loam, a combination of clay and sand is a garden soil that is enriched with hummus. This is a very basic quality and suits mostly all plants. You can use this soil and just add plant specific fertilizers to it. Many successful Japanese miniature gardeners use loam as the garden soil.
Compost:
If you have rare and expensive plants in your miniature garden it is well worth it to invest in compost. You can buy already mixed compost or mix it yourself to suit the needs of the plant. Nurseries are well equipped to recommend a particular type or mixture. The best formula for creating compost is to have three parts sterilized soil, one part granulated soil and one part of a course silver sand. You may need to make adjustments based on the plant needs. You may need to add particular fertilizers based on the plants you have as well.
Filling your Japanese Garden:
Layer your prepared compost or soil over the peat, and sprinkle on water. Press this layer down firmly. The next layer should be for the stones or rocks to be set. Use the same soil mixture and press down firmly again. Check the soil level in the first week to make sure it does not subside.
The Top of the Garden:
After the operational level is finished, you will want to add a top dressing of bone meal over the surface, along with some light chippings of limestone and granite. This prevents your soil from eroding with wind.
Filling a Dish Garden:
When creating a dish garden, it is best to use a porous earthenware type of bowl. You can always place the earthenware dish into a more decorative container. Make sure there are drainage homes, and that they are filled in particularly. It is best to cover the bottom with a thick charcoal layer. The drainage layer should be placed over the charcoal.