On 5/7/04 9:02 am, in article , "Jeannie"
wrote:
snip
I have absolutely NO IDEA of the science behind the Epsom Salts but all I
can say is that I have been given this remedy by more than one fellow
gardener and it works, so that's good enough for me!
snip
It's a very old 'remedy' and I found this on a web site
Soil pH
How well plants grow can be strongly influenced by whether the soil is acid
or alkaline. Itıs best to get the pH right before dealing with other
nutrient problems.
Lack of magnesium
This appears as a lack of green in the leaves. The area between the veins of
leaves, especially the lower older ones, goes yellow. Sometimes the leaf
margins also lose their green colour. Plants of the cabbage family sometimes
develop a purplish colour.
Sandy soils are most likely to lack magnesium. This deficiency is also seen
when there is plenty of magnesium in the soil, but the roots cannot take it
up because of poor soil structure, drought or water-logging. When the
underlying problems are resolved the magnesium deficiency disappears.
Fast-growing plants may show a temporary magnesium deficiency in the older
leaves. This usually sorts itself out when the plant begins to grow more
slowly. There is no need to add extra magnesium.
Common magnesium fertilisers
The amount of magnesium in fertiliser has to be stated on the packet.
However, few compound fertilisers contain it, as plants need much less
magnesium than nitrogen, phosphorus and potassium. Both Epsom salts
(10% Mg) and kieserite (16% Mg) are fast-acting, water-soluble fertilisers
containing magnesium sulphate.
Kieserite contains less water in its crystals than the more frequently sold
Epsom salts and is usually cheaper to use when treating large areas. Because
it is less soluble, it can be used in seedbeds, where Epsom salts could
scorch delicate young roots. Epsom salts are used for foliar feeding, as
they are more soluble in water than kieserite. Neither fertiliser is
organic.
Magnesium is easily washed out of soils that contain little or no clay.
Since these soils are often acid and need lime, maintain the pH using
magnesian limestone. This ground limestone, derived from magnesium-rich
rocks, is also known as Maglime or Dolodust. See the Lime Factsheet (GWF394)
for details of how much to use and where to get it.
Magnesian limestone is acceptable to organic growers, but do not use it
where you intend to grow acid-loving plants like rhododendrons and heathers.
Foliar-feed these plants instead * especially rhododendrons which can suffer
from magnesium deficiency.
Some liquid fertilisers contain a little magnesium * these are a useful
pick-me-up for container-grown plants * tomatoes in growing bags, for
example.
Manure, seaweed, compost and mushroom compost contain small amounts of
magnesium. Cattle manure, for example, contains 0.04%Mg.
Magnesium and potassium
High levels of potassium (K) in the soil suppress plantsı uptake of
magnesium, so avoid overdosing with fertilisers containing potassium.
Conversely, overfeeding with magnesium fertiliser can induce a potassium
deficiency in plants. Foliar feeding helps overcome this imbalance.
General guidelines
If your soil has not been analysed recently and you believe that plants are
showing magnesium deficiency, try a foliar feed in the first instance. If
this has some effect, the soil may be deficient, and applying a magnesium
GWF395
Updated Dec 2003
Magnesium
fertiliser should be worthwhile. Spreading 30g a sq m (1oz a sq yd) of Epsom
salts or kieserite will provide sufficient magnesium for most soils.
Suppliers
Magnesian limestone, Epsom salts and kieserite:
LBS Group
Cottontree, Nr Colne,
Lancashire BB8 7BW
0870 873300
www.lbs-group.co.uk
Garden Direct
Dept MO Unit,
40 Hillgrove Business Park, Nazing Road, Nazing,
Essex EN9 2BB
01992 890770
--
Sacha
(remove the weeds after garden to email me)