Summer Vegetable Garden Nutrient Deficiencies

The yellowing of this formerly green pepper plant is a sign of nitrogen deficiency that often crops up at the end of the growing season when soil is depleted.

Organic gardeners must be readers of signs, which are the silent and often subtle ways plants communicate their needs to us. Summer vegetable garden nutrient deficiencies appear as changes that indicate something isn’t right.  They’ll show up during the heat of midsummer vegetable gardens because plants are working overtime to mature and reproduce, which requires optimal nutrition.

BG Earthworm Casting frontIt’s not unusual to find signs of nutrient deficiency in raised beds.  This is because the original potting soil may have been poor quality, or has simply worn out over the first year or two because vegetable plants are heavy feeders.  If the soil is depleted, the plants weaken, resulting in minimal yields, small size and perpetual problems with pests and diseases.  Raised beds must be liberally fortified with organic amendments and fertilizers each year to compensate for what was consumed by the plants over the previous growing season.

When garden soil is lacking one or more nutrients, plants often show it by changing color.  Their emerald foliage may fade to yellow green or develop yellowing is visible in stripes.  Sometimes just the leaf veins are green with yellow spaces, or the veins are yellow with green spaces. Poor leaf color can indicate disease, but often it is due to chlorosis, a result of a macro- or micronutrient deficiency. Macronutrients are needed in larger quantities and micronutrients are taken up in smaller quantities, but both are needed for good growth.

So what are these nutrients?

Macronutrients:  Nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur.

Micronutrients:  Boron, chlorine, copper, iron, manganese, zinc, molybdenum and nickel.

If your plant is experiencing chlorosis, or you see other curious signs, you may never know exactly what nutrient is absent or deficient.  The best solution is a shotgun approach using amendments or fertilizers known to be rich in a wide range of nutrients.

macroNutMagnesiumBlack Gold Earthworm Castings is perfect for solving micronutrient deficiency.  Castings are rich in all sorts of minerals derived from the fertile soils where worms lived, and these can be easily introduced to your soil and root zone.  For a larger scale application, cultivate dry castings into the soil around each plant or along each row, then water generously so the material works it way deeper down.

For smaller gardens and raised beds, an application in solution generates more rapid results.  Mix castings into a bucket of water, then ladle or pour out this “soup” onto the soil around each plant.  Be generous because this is not a concentrated fertilizer, so it won’t burn. It’s impossible to overdo it.

Sometimes young gardens that haven’t benefitted from years of soil amendments can experience macronutrient deficiencies, such as low nitrogen.  Because nitrogen is responsible for leaf and stem growth, the plant will show signs of being stunted or it simply languishes when it should be thriving.  To test for a nitrogen deficiency in organic gardens, work alfalfa meal into the soil and water generously.  If the plants begin to put on new growth and larger more lush leaves within a few weeks after application, you’ll know it’s a nitrogen problem.

BG-Fert-All-Purpose-OMRI-120608Both macro and micro nutrient problems can be avoided altogether by adding quantities of rich organic amendments such as Black Gold Garden Compost and an all-purpose fertilizer in both spring and fall.

Avoid resorting to poor-quality, less natural fertilizers as a quick fix to nutrient deficiency because it’s only short term and not beneficial to the soil food web.  It’s much like eating a doughnut for energy, which won’t last long, then you feel lethargic and crash from low blood sugar. It matters what you eat, how much you consume, and how often you dine.  Be diligent, because feeding your organic garden generously in spring and fall with slower acting organic amendments and fertilizers ensures it remains chlorosis free and consistently fertile all year, every year.

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Here is the same pepper several weeks after fertilization and good care.


Fight Chlorosis with Earthworm Castings Tea


Cure Chlorosis - Maureen Gilmer
The foliage of this squash plant shows varying degrees of chlorosis compared to a few normal, all green leaves. Note the green veins within the yellow leaves that distinguishes nutrient deficiency from pests and diseases.

My squash are screaming at me from the back of my garden in the silent language of plants. The big green leaves of my most productive summer squash are turning yellow. This isn’t a water problem because there is no wilt. Closer inspection of the leaves reveals no pests either. Only the veins of the leaves are still green. This condition is called chlorosis, and it can strike virtually any plant that’s experiencing a nutrient deficiency. But don’t let it get you down. Let’s learn more about the condition and how to cure chlorosis with earthworm castings tea.

Plants need two types of nutrients to grow. First are the macro-nutrients we all know from fertilizer packages, which are nitrogen, phosphorous and potassium. These also include to a lesser extent, calcium, magnesium and sulfur. The list of micro-nutrients is much longer, but these are all needed too, often in small quantities and sometimes just a trace. Among the most vital are boron, iron, manganese, zinc, copper, molybdenum and chlorine. The absence of any of these can cause chlorosis.

The actual nutrient deficiency I’m experiencing may be impossible to nail down exactly, and that’s not really necessary to solve the problem. Often folks assume it’s a nitrogen deficiency, but in my case all the other plants around that squash are nice and green, so that isn’t it. Plus, adding nitrogen rich fertilizer to green-up certain summer vegetables is not the best idea. Those that produce their crop via flowers and fruit such as cucumbers, tomatoes and peppers, may stop flowering, which means no more fruit. Sure they’ll grow big and leafy as a result, but that will interfere with future yield.

The best way to rescue a chlorotic fruiting vegetable plant is to provide a multi-vitamin approach that brings a wide range of macro and micro nutrients into the root zone at the same time. However, for rapid uptake, it must be in a form that’s immediately available to the plant.

Black Gold Earthworm Castings are an all organic fertilizer-like material that is renowned for containing a wide range of macro- and micro-nutrients. That’s why it’s present in many other Black Gold products too. What makes earthworm castings so great is that these nutrients are held in a water soluble form. When applied in a water solution, they enter the root zone and are taken in by that hungry squash immediately.

How To Make Earthworm Castings Tea

If you’re experiencing chlorosis, or a plant that’s simply a poor-doer, create a tea out of earthworm castings and pour it directly onto the root zone of your plant. Though nutrient-rich, there’s no risk of burning the roots. Simply mix one cup or more of earthworm castings into one gallon of water. Be sure to mix again just before you pour it onto your plants to make sure any settled nutrients are again in suspension for even distribution.

Chlorosis in your leafy vegetables such as lettuce or cabbage is treated slightly differently. With these, lots of leafy growth is desirable since this is the part you eat. For these, work in a quality tomato and vegetable fertilizer, then water it in with earthworm castings tea to make sure you’ve covered all he bases. Since all these are OMRI listed, you can confidently apply your nitrogen to leaf crops at any time during the summer or fall season.

Gardening is about recognizing the silent language of plants and interpreting what it means. When leaves turn yellow, be sure to note whether the veins remain green to determine if it’s chlorosis or something else. Then consider if it’s a crop that depends on flowers, or one that’s foliage-based. That tells you exactly how to treat them with confidence using Black Gold all organic fertilizers and potting soils.