Fertilizer on herbs?

annewaldron(SoCal,10)September 9, 2005

Okay, I fear I'm going to get an "it's all about the soil/drainage" reply to this post, but my container-grown herbs more or less just don't look all that great. I have a bunch: basil, parsley, oregano, thyme, dill, cilantro.

- Basil used to look good, but then it got woody. I chopped it back and it just looks terrible now! Yellow-green looking leaves with blemishes on them..

- Parsley actually looks OK but I haven't had a lot of new growth lately and the leaves aren't exactly the rich dark green color they used to be...

- I overwatered the english thyme and it went woody, now it looks terrible and doesn't seem to have a lot of new growth

- the silver thyme has got dark spots on the underside of all the leaves and just looks generally unhappy

- cilantro immediately bolted, so I'm letting it go to seed

- the others are too new to look bad, but I'm sure they'll go downhill eventually too!

I potted in nursery bought potting soil. I've added wicks to the shallower pots. I've learned not to water so much and have been letting them get a bit dry between waterings.

What next? Fertilizer?



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andy_e(SF Bay CA 9/14)

I'm not sure if it's seasonality or something else. In general though, you should fertilize herbs in containers because they have no other way to get additional nutrients once they've used up what's in the pot. You could try 1/4 strength once/week to start off with and see how that goes.


    Bookmark   September 9, 2005 at 5:31PM
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Since I'm a newbie, could you be more specific about what it is that I need to use at 1/4 strength? Is there a certain fertilizer type I should be using?

    Bookmark   September 9, 2005 at 7:40PM
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katwomn59(8b-Austin, TX)

I use organic stuff: Neptune's Harvest's seaweed/fish emulsion (2-3-1), and some other organic stuff made locally. It has low numbers so I use it full strength every other week on my herbs. If you use chemical ferts they usually have higher numbers so that is why you should dilute them. Most herbs dont need a lot of fert. I didnt fertilize my herbs when I first planted them either and after a month they started looking pretty sad. But once I started fertilizing they looked a lot better. I am pretty new too and never planted anything before this season. I have learned a lot here. Keep posting and asking questions, there is a huge knowlege base on these forums!

    Bookmark   September 9, 2005 at 8:00PM
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katwomn59, I looked up the fert you mentioned and found their web site. How do you buy yours- did you find it locally or purchase online? I'm willing to give it a try...I get nervous about all the chemical-looking ones I see at Home Depot...


    Bookmark   September 9, 2005 at 8:09PM
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tapla (mid-MI z5b-6a)

Stop with the pessimism already!! ;o) First, basil & thyme are woody perennials & you should expect them to grow woody. Cilantro always bolts - and it's not unusual for plants to look a bit rugged in the heat of summer, so take it easy on yourself. ;o) It could be drainage/aeration, or it could be a combination of a number of possibilities. High root temperatures can create all sorts of physiological difficulties for plants. It affects root metabolism and slows photosynthesis for extended periods, even when temperatures return to a favorable range. You can help by allowing soil to remain on the dry side, but not allowing plants to wilt. If plants DO wilt, check soil to see if it's still moist. If it is, resist the urge to water & move the plant to shade. I'm not sure of what your climate is (humidity) but I avoid wetting foliage when I water - especially late in the day. When you do water, watering during the hottest part of the day can reduce root temperatures by as much as 30* or more, a great benefit to o/a root health.

You'll find nothing written in any credible texts to indicate that fertilizing at the recommended concentrations and at the recommended intervals will "burn" roots. Most tender of all roots are newly formed adventitious roots on cuttings. I have used full strength concentrations on cuttings for many years with no ill effect. If you come across a starving animal, would you feed it 1/4 of what he could eat, or a full serving. If you were sick, would you take only 1/2 your prescribed medicine? Fertilizers are carefully crafted to be delivered in a concentration of salts that produces a specific range of electrical conductivity in which nutrients are most readily absorbed by the plant. Changing the solution changes the range. IF your soil drains well & you are watering properly, you should be able to fertilize at recommended concentrations and intervals. It makes much more sense to look to a soil that allows you to water and fertilize freely and properly than it does to systematically under-fertilize to avoid fertilizer salt build-up because a soil falls short in the drainage dept.

To illustrate: I grow many pines and junipers in 5 gallon nursery containers whose ht has been shortened by half. The soil I use for these plants is 10% fir bark, 45% Turface (a baked clay granule - kind of a porous ceramic) and 45% crushed granite. This soil has only a 10% organic component. For the plants I want to rapid growth in, I fertilize with a full strength concentration of 20-20-20 granular fertilizer plus, I add 5-1-1 fish emulsion in full strength concentrations to the solution. Because all my soils are highly aerated and drain very well, I am able to do this weekly. I have never seen a single sign of fertilizer burn. I use a similar strategy in my other floral garden containers that are in a 90% organic mix. At the first sign that leaves might be showing some yellowing, I fertilize with a full strength mix of 3-2-1 fish emulsion plus 20-20-20 granular. If leaves show good color, I use 5-1-1 fish emulsion plus 10-50-10 granular to increase bloom profusity. (I'm not suggesting you or other readers adopt this nutrient supplement program, but it suits my growing habits very well.)

Don't get discouraged Anne. I see your questions all over the forums. You'll succeed because you want to learn. While you're gaining more & more knowledge, your growing success will grow exponentially as the pieces of the puzzle & procedural keys fall into place.


    Bookmark   September 9, 2005 at 9:44PM
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tapla (mid-MI z5b-6a)

Sorry - the fish emulsion I listed as 3-2-1 should have been 2-3-1 and is the same product that Lydia mentioned. I consider this product particularly good at stimulating blooms on flowering plants for those who want an organic. For other than floral display plants, you may wish to consider alternating or combining it with a 5-1-1 fish product which is higher in N. Both these products are slow-acting as they must be broken down by microbial activity before they are able to be utilized by plants.

    Bookmark   September 9, 2005 at 9:57PM
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username_5(banned for no reason)

Your plants sound normal to me. Herbs are kind of... wildflowerish. They do their thing, but they don't all have long seasons. Growing herbs in pots is just fine and yes they ought to be fertilized much more than in the ground herbs, but no matter what they are going to decline in a single season.

If you get a book on herb growing you will find advice on when to harvest each herb. It does make a difference and if you wait too long they are past their prime.

The fertilizer you use isn't terribly important as they all work more or less, but for potted plants a liquid fert is prefered over granular ferts for efficiency. Personally I prefer organic ferts over synthetic, but that is only because synthetics usually contain a lot of salts and this can build up over time in potting soil. In the ground it isn't as much of a concern.

With herbs you really need to get a book and read about each type you are growing as their needs are not all the same nor is the optimum harvest time the same. A good book will not only tell you how to meet their needs, but will give you all sorts of ways to preserve and utilize them.

This isn't rocket science and while there is a learning curve, it is a shallow one. A couple years of growing, harvesting and using along with a good book will turn you into an herb guru.

    Bookmark   September 10, 2005 at 2:33AM
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tapla (mid-MI z5b-6a)

Clarification: The granular products I mentioned, 20-20-20 and 10-50-10 are both products similar to Miracle Grow and Miracle Grow's blooming plants formulation and are meant to be applied in solution.


    Bookmark   September 10, 2005 at 9:25AM
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Ah, all of your replies are making me feel better! Obviously you could read the sense of failure in my post! And yes, I am asking TONS of questions because it feels like I'm learning a new language! A new lesson every day it seems...I'm also reading The Idiot's Guide to the Middle East Crisis- perhaps I ought to put that one down for a while and concentrate on my plants- hahaha!

Anyway, I found a reasonably-priced fish emulsion 4-1-2 that I'm going to dilute according to the directions for potted/house plants (1/2 tsp:1 qt. water) and add to my herbs at their next watering.

And I'm going to breathe deep and know that it's not about perfection!


    Bookmark   September 10, 2005 at 4:20PM
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No mention of controlled release fertilizers? I think it is difficult to adequately fertilize container plants by relying solely on water soluble fertilizers of any type. These can create a "roller coaster" feast or famine effect for the plant--nutrients are abundant when you apply the fertilizer, then flushed away at the next watering without fertilizer. Controlled release fertilizers (osmocote, nutricote, multicote, etc.) on the other hand, provide a consistent nutrient base for the plant. I prefer to use the slow release pellets in conservative amounts, while adding soluble fertilizers during peak growth periods. By doing this, the plants are never completely without nutrients at any time. Slow release fertilizers alone can also be problematic--too much nutrient release in extreme heat when many plants are semi-dormant. This is why I prefer to use them conservatively while using soluble ferts to adjust the nutrient level according to a plants needs. Also, most slow release fertilizers commonly available have no micronutrients, while many soluble fertilizers do--especially important if you are not using a granular micronutrient supplement.

As for the 1/2 strength, 1/4 strength, full strength question--I like to apply in 1/2 strength or less, the thought being that I can apply more often and avoid the feast/famine effect. (But I'm not yet familiar with the electrical conductivity effects of changing fertilizer concentrations, Al will have to fill me in).

In short, and to make this pertinent to Anne's original question--I suggest sprinkling in some slow release pellets in your herb pots, then use the fish emulsion on occasion as you see fit.


    Bookmark   September 11, 2005 at 6:39AM
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