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Which fertilizer should I use to grow larger leaves on coriander plants?

I have read this question - What could cause my coriander plant to start browning? Which talks about over water logged soil causing rotten roots that cause brown leaves. But it did not answer my question.

Thank you for any advice you may give.

6

Use a fertilizer high in nitrogen. This is true for most herbs and grassy plants like corn because

Nitrogen is primarily responsible for vegetative growth.

it is also responsible for

increased yield and quality

source

Nitrogen, Phosphorous, and Potassium are the three major macro nutrients that plants use. Fertilizers show what percentage of each of these nutrients they have with an N-P-K number that is usually highly visible on the bag. So if you fertilize your coriander with a fertilizer with an NPK of, for example 5-1-1 or 10-0-0, that would be a good choice.

  • Yep, nitrogen is the main one... the others are important too, I'd personally go with a high nitrogen, with fair amounts of the others as well. – J. Musser Jul 10 '15 at 22:19
  • Rock phosphate certainly seemed to increase the size of my indoor Rocoto pepper leaves, but it didn't seem to help my outdoor coriander much. Maybe I didn't use enough on it. Nitrogen should certainly help, though, as J. Musser says. Whether or not it helps best with leaf size, you should get bigger, more vegetative plants. I would still experiment with phosphorus, personally, though, for leaf size. However, it may also help the plant to mature faster, which may not be as desirable with coriander, since that potentially might help it go to seed before it grows very much. – Shule Jul 11 '15 at 10:49
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You should use rich soil and a balanced NPK fertilizer but supplement it with additional N and add calcium.

This promotes good, fast growth, but leaf size is a matter of the strain of coriander and especially the temperature. In many regions it is considered a spring and fall crop because once temperatures get above about 75F and the plant has matured a few weeks (at most), it will bolt and produce much different looking thin lobed leaves.

If you're growing it for the cilantro leaves, not the coriander seeds, then your best bet is having a lot of grow area. Rather than trying to get each plant large for more leaves, you want more plants in total, but you don't want them spaced so closely together that more energy is put into stem length.

When harvesting leaves, thin each plant such that leaves aren't overlapping each other as much. This tends to mean pick them from the middle, not the ones hanging out on the edge which are a quick lazy way to get some to use, but will make the plant produce more stem to (lower) leaf ratio.

As far as watering goes, if they are in pots, try not to water enough that any water runs out the bottom of the pots. If they are in the ground, try to resist watering until they show signs of droop, then give that soil a good 1" X area water volume as a start, then adjust to more water at a time if you find that you have to water more often than once every two days.

When watering, try to avoid getting the leaves wet as they are thin, delicate leaves and water can easily cause magnified sun damage. Also avoid foliar feeding since that makes it all the more of a hassle to rinse the leaves sufficiently prior to consumption, as they are easily bruised in handling.

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I'm not an expert, but since previous answers seem to be pushing nitrogen I thought I would point out this document out of Utah State University, which warns against going heavy on the nitrogen:

http://extension.usu.edu/juab/ou-files/ez-plug/uploads/Horticulture/herbs/cilantro2006-04.pdf

Your mileage may vary.

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This article (http://hortsci.ashspublications.org/content/30/4/884.4) says N & P at equal ratio are effective, K not significant. This will also depend on growth stage (veg., fruit.) - Good Luck

  • 2
    The link abstract says P is not significant for cilantro, but useful for dill. Did you read it differently? – Graham Chiu Jan 15 '17 at 19:31

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