Large Scale Basil Growing and Problem with Fading Leaves
Answered by: Inge Poot
Question from: Marlon Ortiz
Posted on: January 18, 2008

I just started to plant basil (on 5 acres rented by my father) and already the colour of the leaves is fading and the leaves are not growing as well as they did at the start. Can you help me out with what type of fertilizer I should be using -- maybe an organic one?

You do not say where you are located, so I do not know what climate you are exposing the basil to. If you transplanted seedlings that you started indoors, it may be too cold for the plants or too sunny compared to the conditions they were exposed to before. You would have to harden up the seedlings before planting them, by gradually exposing them to the full sun over a period of two weeks. If you are farming in a cool climate, make sure you do not plant out basil until the outside temperature is over 15 degrees Celsius even at night.

If you direct seeded outside and the plants were doing fine for a time, but then started to go downhill without any root disturbance, then I would expect disease. Basil is attacked by a fusarium wilt that eventually kills it. The spores remain in the soil for a long time and once the field had the problem, the only remedy is to use fusarium tolerant strains of seed. Richters sells at least two types and I can only recommend it.

Another possible problem might be lack of adequate drainage. A dense soil would be loose from cultivation at first, but soon pack down again especially with rain or irrigation and kill the plants slowly by suffocating the roots. In this case you would have to work either lots of humus into the soil or solve the problem once and for all, by working lots of sharp sand into the soil.

I think organic fertilizer is always the better choice, since you are growing a food product and will get a healthier product. A fertilizer high in the first number, the nitrogen would in general be your preferred choice, since you are growing leaves not roots or flowers. If the soil has some sort of mineral imbalance that recommendation may not hold true in such a case. You would need an analysis by a laboratory to find out what your soil is missing and then add the missing minerals. In Ontario, Canada this service is available from local county agricultural offices, but I cannot advise you who to turn to in any other area.

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