Potted plants may need to be moved into a new pot with fresh, dry potting mix.
For in-ground plants, hold off on irrigating until soil has had a chance to dry out.
Poor Drainage
Poor drainage also leads to root rot and yellowing of leaves.
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Loosen compacted soil with aged compost or sand prior to planting.
A mix of compost and potting soil also allows for good drainage in potted plants.
Leave plenty of space between plants; 12 to 16 inches in the garden bed.
Avoid crowding too many plants in one pot.
Basil grows best in large deep pots with about 3 gallons of soil for each plant.
Nutrient Deficiency
Feed basil withbalanced NPK fertilizerslike 10-10-10.
Nitrogen deficiencies can cause leaves to yellow.
Add compost to garden soil before planting to boost available nutrients.
Potted plants benefit from regular feeding every two to three weeks throughout the growing season.
It does not tolerate frost.
However, extended periods of temperatures above 80 degrees F. can cause leaf burn.
Edges turn brown, and leaves yellow, eventually die, and drop off.
This, in turn, promotes branching and more leaves.
Look for webbing underneath or between leaves.
Depending on how bad the infestation is, severaltreatments with neemor a horticultural oil might be needed.
Pull the infected plant, remove any usable leaves and put the rest of the plant in the trash.
Fusarium wilt is another fungal infection identified by yellowing leaves with brown spots.
There is no cure for fusarium wilt, so plants should be removed and disposed of.
A basil plant could have yellow leaves with brown spots because of downy mildew or fusarium wilt.
For fusarium wilt, best to pull the plant and throw it away.
10, 2022, pp.
1466-1479. doi:10.1080/01904167.2021.2014885
Basil downy mildew.University of Minnesota Extension.
Fusarium wilt in basil.
University of Maryland Extension.
