Why do my herbs get yellow leaves?

Question

i am growing my herbs in small pots in the balcony, now its august in scandinavia. so why do the leaves get yellow. like rosemary, and thyme and coriander? thanks!!

Answer 1

Older leaves at the bottom of plants turn yellow & fall off naturally, but there is a possibility that the leaves may be turning yellow because the plants may be over watered or the plants may have "wet feet," a result of  lack of drainage.  They may have grown too large for their pots & may need to be separated and repotted.

http://www.apinchof.com/basilqanda.htm

This forum also discusses herbs leaves turning yellow from over watering:

"Over watering is the biggest cause for plants death. A good indication is 'chlorosis' that makes leaves turn yellow and drop off."

http://forums.gardenweb.com/forums/load/...

http://forums.gardenweb.com/forums/load/...

Of course, if you neglect to water or water inconsistantly, or pests are sucking the life out of your plant it will also cause it to be stressed out & its leaves will also turn yellow & fall off.

But the fact  that you mentioned that your plants were growing in small pots ...& I'm assuming for quite a while...brings me back to the possibility that they may be over crowded, have "wet feet"  & may need to be repotted.

Make sure that your herbs have good drainage & are getting enough sunlight & check to see that you're not overwatering or underwatering.  Different herbs have different moisture requirements. Rosemary & thyme can take dryer conditions better than coriander. "Thyme is most fragrant and flavorful when grown in dry, lean soil. Too much moisture will rot the plants."

http://gardening.about.com/od/herbsspeci...

"Rosemary likes it on the dry side":

http://gardening.about.com/od/vegetablep...

"Water coriander in dry periods and ensure the soil never dries out.  Coriander enjoys a sunny position but appreciates a little shade during the hottest part of the day."

http://www.herbexpert.co.uk/GrowingCoria...

Good luck!!!    Hope this is helpful.