Hello, my son and I collected acorns in the fall and kept them in the fridge till spring when many started to grow roots. We placed them in vases and they have been growing well until recently when two developed brown spots on leaves that then started to wither. Now all the seedlings have brown spots. We would love to know what this is and how to deal with it.
Thanks for contacting Toronto Master Gardeners with your question. Growing plants from seed – especially seed that you collected yourself – is so exciting!
It looks like you have the oak seedlings growing in water, so it is highly likely that they are experiencing a nutrient deficiency, as water may not contain the micronutrients required for proper photosynthesis and growth. Based on your photo, it could be an iron or magnesium deficiency. The simplest possible remedy would be to move your seedlings into soil. If you haven’t yet decided where to plant them in the ground, plant them in pots for the time being and use a good quality bagged potting soil. Either way, you will want to gradually expose them to outdoor conditions – a process known as hardening off – as they have been growing in very protected conditions indoors and have not yet been acclimatized to fluctuations in temperature, wind, sunlight, etc.
You can find some additional information on planting and growing oak trees in one of our previous Ask a Master Gardener posts.
April 26, 2024