Courtesy of Lois Thompson, Sprout Consultant, Mumm’s Sprouting Seeds
A SPIN farmer who has gotten off to an impressive start with a microgreens business, Mary Ackley of Little Wild Things City Farm in Washington DC, posted an SOS in the Backyard Riches forum about yellowing micro basil. She has both an indoor and field grown operation, and reported that suddenly two different batches of tray grown micro basil have exhibited yellowing leaves. There is no sign of infectious diseases (fungi or bacteria) or any pests.
If you can’t get advice from someone who has experienced your exact problem, you may have to troubleshoot crop problems like this one your own. Lois Thompson the sprout consultant at Mumm’s Sprouting Seeds,outlines a 6 step troubleshooting process which involves reviewing soil, light, watering and atmosphere to identify changes in any of these condition which would cause a good crop to become a bad one.
>>Starting premise: If 2 kinds of seeds have the same problem, it is likely not the seed.
Assess what has changed from when you were able to grow the leaves green. The change can be subtle.
1. Start with the soil.
– Did you get in a new lot of soil? – Anything new about the soil? –
Yellowing could be a nutrient deficiency in iron, magnesium, manganese, zinc, or nitrogen, due to high or low soil ph.
o if there is an strange pattern to the yellowing, like if the veins on the leaves are green and the tissue is yellow then it is almost always a nutrient problem.
o Try some kelp fertilizer
o Try some worm castings or compost into the soil
2. Look at the roots. – – – Damaged roots, compacted roots, injured roots, poor root growth could lead to nutrient deficiencies showing up in leaves
– Try adding a soil amendment like mycorrhiza – Try adding sugar to the water or the soil try different concentrations
3. Look for moisture stress – Any new drainage problems?
4. Look at your watering – Any signs of the crop getting too much or too little water? – Any change in water temperature? – Call the city to ask if the water has changed? Has salt been added to the water? – Any subtle seasonal water changes?
5. Look at your light – Has the light changed? Try some extra light. Try additional LED lights
6. Look at air circulation and temperature
– Have there been seasonal changes in temperature?
Farming is never steady state, and disciplined experimentation is a tool of the trade. It’s much easier to deal with SPIN-scale production challenges, and it’s important to note that while indoor production has been extolled as the 21st century solution to feeding the world, controlled climate growing does not mean that the grower is always in control.