A phosphorus deficiency in your plants will cause stunted growth and prevent them from producing fruit as expected, yet is often overlooked or misdiagnosed as a nitrogen deficiency. Although it is a bit difficult to determine for the untrained eye, with a little effort you can learn to recognize signs that your plants are suffering from a phosphorus deficiency. Correcting the problem early will resolve the issue and your plants will thrive.
1. Small thin stalks. Plants that do not receive enough phosphorus develop weak, thin stalks that appear spindly. Healthy plants need strong stems to support the weight of the developing fruit. Thin stalks are not able to support the fruit and break easily in the wind. If your plants fail to develop stocky stems, phosphorus may be the culprit.
2. Stunted growth. Plants suffering from a phosphorus deficiency may be stunted and short in stature. In initial stages, they may appear healthy and look like much younger plants. If your plants are smaller than expected or smaller than other plants of the same age, they may need additional phosphorus.
3. Purple veins or a purple hue to the undersides of leaves. Check both the top and bottom of the leaf for purple veins. This is evident on new growth as well as older leaves. In severe cases, the entire leaf may take on a purple hue.
4. Older leaves may appear bluish-green. Instead of the characteristic rich green of new growth you may notice leaves taking on a bluish tint. Unless the plant foliage is typically blue-green (like in broccoli and cauliflower), blue-green leaves typically signal a lack of phosphorus.
5. Reduced blooms and/or onset of fruit. Phosphorus promotes blooming and fruit production. A deficiency may cause the plant to stop producing blooms or the blooms and fruits to be small and lack their usual color. For good fruit production, plants require phosphorus.
Tomato plants, like one above are susceptible to a phosphorus deficiency. Adding plastic mulch to increase soil temperatures may solve the problem, if the deficiency is due to cool soil.
To increase the level of phosphorus in the soil, apply high phosphorus fertilizer (usually labeled as fertilizer for blooming plants). Miracle-Gro for tomatoes is high in phosphorus.
It's that time of year when nutrient deficiencies begin to cause problems in the garden. While most of us have given our plants a good start with starter fertilizer, many plants need supplemental fertilizer during the growing season. One of the most common nutrient deficiencies in a typical Maine garden is nitrogen. Without adequate nitrogen your plants cannot build the nucleic acids and proteins they need for healthy growth and fruit production. A lack of nitrogen is often misdiagnosed as a lack of (or too much) water or attributed to the weather. if your plants are looking a little pale and don't seem to be growing as they should, check them closely for these signs of a nitrogen deficiency.
Replenishing the usable nitrogen in the soil often produces rapid results. You may notice increased growth and richer color with a few days. You can add nitrogen by adding compost, well-rotted manure, fish emulsion or commercial fertilizers.
Water-soluble fertilizers designed as foliar feeders can be mixed and sprayed onto the plants. Allow adequate amounts of fertilizer to penetrate the soil. Look for mixtures that are high in nitrogen, denoted by the first number in the formula. Always follow the directions included on the container to avoid over feeding and damaging your plants.
Note: A soil test meter is a great investment for monitoring the pH and nutrient levels in you soil. It only takes a minute to complete the test and takes the guess work out of troubleshooting problems with your plants.
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