J. A. of Gianyar writes: I recently moved into a new villa whose existing garden was not in good condition. I have decided to start again from the beginning, but as parts of the garden are low-lying, I have raised the level with in-fill.
This in-fill has come from digging a well and is mostly sub-soil. I realize that this soil is not ideal for plants to grow in and intend to import topsoil to spread over it. My question is how deep should this topsoil be?
The short answer is a minimum of 15cm; a better answer would be to make it as deep as you can afford. Other things do come into consideration, but as you have not supplied me with more details I can only work on certain assumptions – ie:
How big is the garden area? This (and the depth of your pocket) will decide the amount of topsoil. How deep is the in-fill? Do you intend to garden intensively, or are you setting aside areas for grass and/or paved areas? Have you considered an ornamental pool situated in the lowest part of the garden? Are you concerned principally with trees, shrubs and flowers, or are you also planning a kitchen garden area?
Before spreading topsoil, I would suggest that you spread fertilizer over the entire garden. The best all-purpose fertilizer would be super-phosphate (Phoska). I do know that rice farmers use both Urea, and Phoska. Sometimes they add some aluminium sulphate and sulphur (5% of each). The rate of application is about one handful per square metre. Do not overdo it! Too much can burn the root system. Unless you have the cast-iron hands of a rice farmer, use gloves - protracted exposure can also burn skin.
If your in-fill is deep (12cm+) this should prevent any weed growth, but remember that you will also import weed seeds with your topsoil, so it is better to allow these weeds germinate and destroy them before any planting is done.
Paved areas will not require topsoil and native grasses will usually grow quite well in sub-soil, though a thin skin of topsoil seeded with a desired grass will provide a better turf.
If you want flower and/or vegetable beds, I suggest that you raise these above ground level and fill them with topsoil (at least 30cm high – 40-50cm is better) plus as much compost as you can scrounge. Cow or poultry manure should be added, but be careful with poultry manure as it is very ‘hot’ unless already 3-4 months old.
Raised beds may be as long as you want, but no wider than you can comfortably reach into the centre for the purposes of weeding. A double row of local bricks is good (but don’t mortar them so that repairs or re-adjustment is easy). Coconut palm trunks can simply be cut to length and staked into place. Unless they are monsters, use two – one on top of the other.
The very best beginning is to sow a green manure crop first. Any legume (peas, beans) may be used. When they just begin to form flower stems, dig the plants into the soil, as you do not want them to set seed and re-grow. Legumes fix nitrogen into nodules on their roots, adding this valuable chemical to the soil, as well as providing compost.
As a former nurseryman, I know that most people want ‘instant garden’. This is more possible here than in any temperate climate. Relatively mature trees and shrubs can be transplanted (to wit the coconuts planted less than a year ago in Jl. Bypass). These are more expensive than young plants. Young plants also establish quickly here if given good care – you can almost watch them growing. Some seeds take as little as 48 hours to germinate.
There are many toko bunga (plant nurseries) along Jalan Hang Tua and Jalan Hayam Wuruk; some specialist suppliers - others with general stock. A wide variety is available and on taking a casual look, plants seem healthy and well-grown.
A further question about frangipani; this reader has many mature frangipani in her garden – some over ten metres in height. She complains that flowers are mostly borne at the top of the trees and their perfume is blown out of her garden. Can she cut them back?
The answer is yes! Evergreen in the tropics, frangipani are at their most dormant here in the middle of the dry season (June/July). They may then be cut back hard, from 50%-75%, safely. Re-growth is then rapid and flowers will soon come again. Regular small quantities of fertilizer and regular watering will hasten this process.
Please send all your gardening questions to
E-mail: writers@baliadvertiser.biz
