Mulching...
Posted: February 1st, 2011, 12:14 pm
This topic may be of use to you if you have a large collection of trees in training. Please note that I am in Melbourne and this method may not suit a sub tropical or tropical environment.
The past few days of weather is what I was waiting for from Summer. Finally there is some fire in its belly.
I have been feeding my trees regularly for the past 12 months and have seen them put on a lot of foliage which means in hot weather that the tree will lose a lot more water with transpiration through the leaves.
I have been prepared for this by mulching all of my trees that are in plastic tubs, styrene or wooden boxes with about 40-50mm layer of 20-40mm pine bark mixed with mushy compost at approximately 50/50. The idea being that when watering, the tree will get a little feed each time I water, the mulch is open enough to allow water to travel freely through it and into the soil.
The mulch has the following benefits,
1.Water conservation through evaporation by reduction in wind action
2.Slight reduction in air movement through open gravelly mixes which reduces evaporation through air movement without suffocating the roots or soil.
3.Evening out of soil temperature through insulation which can benefit root formation.
4.Increased activity from micro-organisms in the soil.
4.Reduced watering time, on an average of sustained 35-40ºc days watering can be done on a 48 hour basis rather than 12-24 hr basis.
5.More time to admire your plants and tend to other issues.
I have of course found some problems and these can be ironed out through observation and a good memory of each plant.
1.Mulching is no good for plants on shelves with soil level at less than 20-30mm below the rim of the pot.
2.The mulch must be pushed aside at a couple of spots inside the container to check the moisture level of the soil, eg at the edge of the container, the middle and near the trunk.
3.Some species won't take to it very well, I have a fairly stable lot so I am able to apply the mulch as a consistent mix for them all.
4.The mulch should not be piled up against the base of the trunk as it may cause collar rot on some Genus.
5.Vermin such as Blackbird (Turdus merula) can get into the mulch and scratch it away looking for food but they are not so active during hotter months. The Blackbird can sometimes break fine twiggy growth around the edge of the canopy. This can be solved by having a net over the mulch or over your collection. A cat doesn't really help as they can do more damage when trying to catch the birds
With a genus such as Rhododendron I have found no trouble with root rot providing you are using a open free draining mix and that yo are not over watering. In fact they seem to like it.
There are no doubt other pro's and con's relating to mulching but these are just off the top of my head through observation over the past 3 years.
The ph of the pine bark is acid at around 4 and the mushy mulch is around 6 based on the Manutec soil test kit chart. I don't expect the ph of the mulch to have any great bearing on the ph of the soil as I have used some well rotted leaf as compost in my mix as a buffer against ph change.
A composted woodchip mulch can also be used. Whether it be a purchased one or made from composting a pile from a cut down tree. If you are using mulch consisting of cut down trees, it is important to check periodically for seedlings which can pop up from seed capsules in the mulch. For ethical reasons I have stayed away from non sustainable materials such as Red Gum Chips as much as possible.
It would be a good thing if you have been practicing this to add some problems or success to the topic.
The past few days of weather is what I was waiting for from Summer. Finally there is some fire in its belly.
I have been feeding my trees regularly for the past 12 months and have seen them put on a lot of foliage which means in hot weather that the tree will lose a lot more water with transpiration through the leaves.
I have been prepared for this by mulching all of my trees that are in plastic tubs, styrene or wooden boxes with about 40-50mm layer of 20-40mm pine bark mixed with mushy compost at approximately 50/50. The idea being that when watering, the tree will get a little feed each time I water, the mulch is open enough to allow water to travel freely through it and into the soil.
The mulch has the following benefits,
1.Water conservation through evaporation by reduction in wind action
2.Slight reduction in air movement through open gravelly mixes which reduces evaporation through air movement without suffocating the roots or soil.
3.Evening out of soil temperature through insulation which can benefit root formation.
4.Increased activity from micro-organisms in the soil.
4.Reduced watering time, on an average of sustained 35-40ºc days watering can be done on a 48 hour basis rather than 12-24 hr basis.
5.More time to admire your plants and tend to other issues.
I have of course found some problems and these can be ironed out through observation and a good memory of each plant.
1.Mulching is no good for plants on shelves with soil level at less than 20-30mm below the rim of the pot.
2.The mulch must be pushed aside at a couple of spots inside the container to check the moisture level of the soil, eg at the edge of the container, the middle and near the trunk.
3.Some species won't take to it very well, I have a fairly stable lot so I am able to apply the mulch as a consistent mix for them all.
4.The mulch should not be piled up against the base of the trunk as it may cause collar rot on some Genus.
5.Vermin such as Blackbird (Turdus merula) can get into the mulch and scratch it away looking for food but they are not so active during hotter months. The Blackbird can sometimes break fine twiggy growth around the edge of the canopy. This can be solved by having a net over the mulch or over your collection. A cat doesn't really help as they can do more damage when trying to catch the birds
With a genus such as Rhododendron I have found no trouble with root rot providing you are using a open free draining mix and that yo are not over watering. In fact they seem to like it.
There are no doubt other pro's and con's relating to mulching but these are just off the top of my head through observation over the past 3 years.
The ph of the pine bark is acid at around 4 and the mushy mulch is around 6 based on the Manutec soil test kit chart. I don't expect the ph of the mulch to have any great bearing on the ph of the soil as I have used some well rotted leaf as compost in my mix as a buffer against ph change.
A composted woodchip mulch can also be used. Whether it be a purchased one or made from composting a pile from a cut down tree. If you are using mulch consisting of cut down trees, it is important to check periodically for seedlings which can pop up from seed capsules in the mulch. For ethical reasons I have stayed away from non sustainable materials such as Red Gum Chips as much as possible.
It would be a good thing if you have been practicing this to add some problems or success to the topic.