Gardens are like kids. They need time, attention and discipline to make them behave as they should.

But there's another simple secret to soil success and gorgeous gardens.

Gardens, just like kids, 'are what they eat' - feed them the equivalent of McDonald's all the time and you'll have a major problem on your hands.

However, unlike dealing with kids, preparing the right 'food' for your garden is a simple exercise - and best of all, there's no moaning about all those greens!

"The first order of business," says gardening expert, Henri Ham of Awapuni Nurseries, "is deciding what to plant.

"Then it's a question of feeding your garden specific nutrients depending on the outcomes you've got in mind."

For example, Henri says, an even balance of nitrogen, phosphorus and potassium (NPK)-based fertiliser will boost the growth of your vegetable and flower garden. These nutrients are vital for developing roots, flowers and fruit.

"But if you're fertilising your lawn that's the last fertiliser you want to use!" laughs Henri. "That's when you use a potassium and nitrogen-based food."

And here's another similarity to feeding the kids - check the product labels to see which synthetic fertilisers contain what nutrients and in what proportions.

All fertilisers list the ratio of nutrients on the outside of the bag. For example commonly used Garden Galore has a NPK ratio of 4:1.4:3. Blood and Bone, another great natural fertiliser, has a NPK ratio of 6:6:0.

Whereas Garden Galore is just great for kiwifruit, ornamental and fruit trees, shrubs, roses and vegetables, Blood and Bone is best suited for use around leaf crops such as lettuce.

You can use the following list to work out what nutritional elements are best for which garden/plant conditions or outcomes.

• Nitrogen (primary nutrient) - provides green leaves
• Phosphorus (primary nutrient) - vital for the development of roots, flowers and fruit
• Potassium (primary nutrient) - for fixing poor root development
• Magnesium (major nutrient) - important for seed development and photosynthesis (the process plants use to convert sunlight into food)
• Calcium (secondary nutrient) - use for vigorous growth and formation
• Iron (minor nutrient) - without this photosynthesis would be impossible. To little iron results in yellowing between the veins of leaves
• Boron (minor nutrient) - this is needed for normal growth of stems and leaves, including fixing yellow leaves
  For example, Henri says, at this time of year many gardeners have problems with their rhododendron, daphne and camellia leaves turning yellow.

"With a quick shot of boron this problem can be fixed in no time at all!

"However for a general all round mix of fertiliser you can't go past a combination of nitrogen, phosphorus, and potassium, like Nitrophoska Blue," Henri says.

For new gardens, fertiliser should be applied approximately two weeks before planting - with the first day of spring just gone, now is the perfect time to begin.

It should then be re-applied every six months.

If you want to take a more organic approach to your fertilising, Henri recommends spreading either home-made or store-bought compost 50mm to 100mm deep over your garden and digging it in.

Another organic alternative, if your garden is already planted, is to use woodchip mulch.

"Mulch made of woodchips and leaves is brilliant at providing soil with essential nutrients. But try to avoid placing the mulch too close to plants to prevent plants rotting," says Henri.

And to really get the soil kicking along Henri recommends introducing worms to your garden.

"Worms are great at making fertile, healthy soil. They aerate the soil and distribute organic matter and nutrients. They also produce their own fertiliser, called castings."

So for a garden which behaves as it should, and grows healthy and strong plants, soil nutrition is the simple secret you've been searching for.