It is a little realized fact – even with some experienced gardeners – that most trees will benefit from feeding. This is particularly the case with smaller ornamental and fruit orchard trees than with the large indigenous trees of parkland areas. Many trees grow well most of the time and rarely show recognizable problems associated with lack of feeding.
However, in a garden situation, things are different. For a start we normally remove most of a tree’s natural food resource – the fallen leaves! Added to that, the tree is almost always planted in an alien environment, with little thought given to its needs relating to feeding – and watering. The deep roots dive far enough into the soil to find the reserves that keep them looking reasonable for most of the time.
You may have noticed the first signs of lack of nutrients in the early summer, with the leaves not looking quite as good as they were in the spring; or as a decline in fruit production later in the year; or even as a poor autumn foliage colouring.
Those trees which are grown for food purposes – fruit trees and nuts certainly need additional fertilizer rather than that which they find for themselves. In fact, feeding of such trees will almost certainly result in extra yield of fruit, but more importantly, a better quality of fruit that eats and stores well.
All can be affected by lack of food. This is normal to a certain extent for all plants look brighter when first starting to grow after the long winter of dormancy. You will probably be agreeably surprised to see the improvement in your trees if you give them the basic feeds that they need – as you would with other plants!
Early spring is by far the best time – even earlier than you start to feed other plants. With trees, the feed takes longer to get where it is needed (in the growth areas. It has further to travel within the tree system, and also before it gets to the feeding roots. The tree will start its uptake of food from the soil long before the leaves and flower buds start to shoot.
Another good time for tree feeding, is in early autumn – just as the leaves start to turn colour. It will take a while for the feed to be absorbed into the tree, so too late to start new growth, but will be stored by the tree ready for a good start in the spring. This late feed is particularly good with fruiting trees. They will have depleted the available food in the ground, during a long growing season in which flowers, setting fruit and maturing of fruit will be carried out.
Tree roots extend out to the edge of the branch and foliage canopy and beyond. This is where most of the feeding roots are, though there will be feeding roots in all areas under the canopy. Feeding root – not the thick anchorage roots – are generally near the surface of the soil, where the topsoil is normally most fertile.
However, they also feed lower down in the soil – collecting the soluble fertilizers which have leached down without being taken up by other smaller plants.
With most ornamental garden or fruit trees, is will be sufficient to surface apply fertilizer and water well or allow the ground water to turn the fertilizer into a soluble state and thereby be soaked into the soil.
Tree feeding fertilizer plugs are available – with slow release chemical formula which will ensure that the feed stays in the feeding are longer, and is also released gradually throughout the growing season. These plugs are normally inserted into the ground, by way of a hole made with a crowbar or similar. Better to apply them at the perimeter of the root zone so as not to damage any of the large roots – which can then lead to other long term problems for the tree.
Liquid fertilizer can also be used as a short term fix, by pouring the feed into such holes. Do NOT use neat liquid feed. Make sure it is diluted according to instructions on the label.
Either organic or synthetic feeds will be suitable, bearing in mind the organic fertilizers take longer to break down into the chemical needed by the tree – and all plants.
The most important element for tree feeding is Nitrogen. There is normally enough phosphate in most garden soils. It will be easier to find compound fertilizers that have all three main feeding element – Nitrogen; Phosphate and Potassium. These will suffice unless you are going to carry out an extensive soil test, which is not very easy to test the soil down at root zone level!
Many trees get incidental feeding from lawn feed applications – in the spring at least. Do NOT apply a combined Weed and Feed mixture near trees. Though a lawn feed without added weed or moss chemicals will be suitable for sprinkle-feeding and watering-in. They are high Nitrogen, and well suited for tree feeding.
A good general guide is to double the dose normally applied for lawns, when using this type of feed for tree feeding. The same applies to general Growmore-type feeds.