Even with a heavy dose of proper composting, many factors can lead to your plants becoming deficient in valuable nutrients. Too much rain could wash away valuable nitrogen, and not enough rain, well, could lead to a whole lot of other problems.
Here are some popular signs that you should be looking out for in your vegetable garden, their causes, and potential solutions.
Are the leaves on your vegetable plants light green to yellow? Does the
growth of your plant seem stunted? Chances are your soil lacks
nitrogen and/or sulfur. A good quick fix is adding blood meal or fish emulsion.
Speaking of the leaves, are they red or purple when they are supposed to
be green? Looks like your soil is low on Phosphorous. Add some bonemeal or rock phosphate to your soil.
If your vegetable plants are producing fruits have you noticed if they
are too small or production seems to be slow? Your soil may lack
magnesium or potassium. Greensand, Epsom salt, wood ash or seaweed are
all helpful answers.
A lot of the same symptoms noted above will appear for the lack of other
nutrients such as iron, copper, and manganese. You should get a soil
reading if you starting seeing a lot of issues. Your local co-op can do
this for you or they sell home kits where you can test the soil yourself.