Spring's perfect combo of warm sunshine and rain means growth is at its most exuberant. All this activity needs fuel to keep it going, so now is the time to get feeding.
What do plants need?
The three 'major nutrients' that plants need in biggest volume are nitrogen (N), phosphorus (P) and potassium (K). As well, they need smaller quantities of a wide range of minor and trace elements.
Plants grow best when they receive all the nutrients they need without one overpowering the uptake of another. A complete balanced fertiliser is the simplest way to achieve this. To make it easy, a wide range of specific plant foods are available.
Organic or inorganic - what's the difference?
Organic fertilisers come from plant and animal waste. Inorganic fertilisers are manufactured from chemical reactions. Some products blend the two.
Organic fertilisers add to a soil's physical structure, improving water holding capacity and drainage, while promoting the activity of beneficial micro-organisms. They release nutrients over a period of time and are generally less concentrated than other fertilisers so need to be applied in larger quantities. The exact nutrient content of any one organic fertiliser is hard to ascertain, but using a range of different organic products helps to approximate a 'balanced diet'. Blood and bone, for example, is a highly effective and long lasting fertiliser for a wide range of plants, but it doesn't contain potassium. Exclusive use of organic manures works best when there is a local supply of free or low-cost manures, not always easy for city gardeners.
Chemical fertilisers do nothing to maintain the physical structure of the soil. However, because they are more concentrated, and we know from the label what's in them, they provide fast reliable results. The nutrient content in 100 grams of general garden fertiliser is roughly equal to 3 kg of organic manure. The risk is over-use, as high concentrations can burn plant roots. Also, any excess 'run-off' is bad for the environment. Over time, soils fed solely with inorganic fertiliser suffer reduced humus content and biological activity. This leads to reduced water and nutrient holding capacity, and the need to add even more fertiliser - a vicious cycle. It's important to strike a balance.
A fast-acting plant food applied as a liquid or powder (washed in with water) will provide a quick boost to growth and greenness. Liquid fertilisers are especially useful for plants grown in containers, and should ideally be added little and often. Use them as a supplement to longer lasting fertilisers.
Pelletised poultry and sheep manures, blood and bone, and inorganic controlled-release fertilisers release their nutrients gradually, more in sync with plant growth. They allow the convenience of feeding less often, while helping to avoid waste and damage from over use.
What about lime?
Adding lime to the soil has many benefits, but it must be used wisely. There are three main forms:
While not soley about feeding - Spring is an ideal time to get your patch of pasture into top notch condition. Support the spring growth flush with lawn fertiliser.
Feeding and frequent mowing is the best way to keep lawns free of weeds but if things have got away on you, spring is the time to act with a selective lawn weed spray. Prickle weed killer is best applied in October or November. Alternatively, try Fiskars Weed Puller for easy chemical-free weed extraction.
Thin or lumpy lawns can be revamped by top dressing with a mixture of topsoil and compost. Small packs of lawn seed are ideal for fixing bare patches.
Regular mowing promotes thick, healthy growth. But if cut too short, lawns are vulnerable to weed invasion. Keep mower blades extra sharp for a clean cut. In spring it's best to use a catcher as excess build up of clippings can invite disease.