Camellia

Author: Wang Junnian (Editor)
Publisher:
Publish Date: 2003-01-01
Features: Most books say, "Water when the soil is dry and when the soil is wet." This is indeed correct, but what exactly does "dry" mean, and when is it not considered dry? This issue is often discussed in general flower books, summarized into three main points:
(1) If the potting soil appears grayish-white, it means the soil is dry and needs watering; if it is dark brown, the soil is still moist, and watering can be delayed.
(2) Tapping or knocking on the flower pot with fingers or a small stick will produce a clear sound if the soil is dry, and a dull sound if it is still moist.
(3) Pressing the potting soil with fingers—hard means dry, soft means moist.
These methods are reasonable but not entirely accurate. The reasons are as follows:
(1) When the potting soil is exposed to sunlight, the surface may initially appear grayish-white, but the inner soil still retains some moisture. Watering at this stage is generally not a problem. However, if the flower pot is placed in the shade, by the time the surface soil turns white, the inner soil will already be completely dry. Watering in winter may not be a major issue, but during the late spring to early autumn in northern regions, it could be too late! Waiting until the soil is completely white before watering is only suitable for plants that prefer dry conditions and dislike moisture, such as plum blossoms. Even for osmanthus, which prefers high dryness and fears waterlogging, this method is not ideal (though it may not kill the plant, it will hinder growth). And for camellias, which love moisture, this is even worse.
(2) Not all flower pots will produce a clear sound when tapped if the soil is dry. For many pots, even when the soil is completely dry, the sound remains dull. This is likely related to the texture of the potting soil (e.g., heavy clay) and the quality of the pot (e.g., scale buildup or cracks on the inner walls).
(3) Heavy soil becomes hard when dry and soft when wet, while loose soil like peat, pine needles, or decomposed leaves remains soft even when dry. Therefore, these three methods should be used in combination as a reference and not followed rigidly as "rules." Different plants require different amounts of water, so the meaning of "dry" varies for each. For camellias, watering is needed when the soil is about 70% dry (still containing about 30% moisture). However, judging this is challenging. A practical method is to squeeze the soil into a ball with your fingers and water when the soil loosens again upon release. This is generally suitable for spring and autumn, while winter requires slightly drier soil (watering should gradually decrease after the frost in October), and summer needs slightly more moisture (watering should gradually increase after the Qingming Festival in April). This is because high temperatures in summer lead to significant water loss through leaves, requiring sufficient moisture absorption by roots to supply evaporation. Additionally, during bud differentiation, slightly reduce water; during flowering, slightly increase it. However, both "reducing" and "increasing" water should not be excessive. Proper "reduction" can promote bud formation, but excessive reduction can hinder plant growth, even causing wilting and death. If the soil is too dry during flowering, buds may not open (visible buds but no flowers), or flowers may be small. Excessive "increase" in water can cause flower cores to rot and fall, and in severe cases, the roots may rot and die.
In general, southern regions are rainy and humid, while northern regions are dry and arid, so camellias in the north should be watered more than those in the south.
Emphasizing Water Quality
When watering plants, attention should be paid to water quality. Not just any water can be used for watering. Plants like camellias, which prefer acidic soil, have specific requirements for water quality.
(1) Rainwater or melted snow is the best for camellias, as they contain no minerals and are beneficial for growth. Groundwater often contains salts and is not suitable for use. Tap water in cities is usually disinfected with liquid chlorine or chlorine-containing compounds like bleach, bleaching powder, or chlorine-based chemicals, which can harm camellias if used directly. It is best to let tap water sit in a container for several days to allow chlorine to dissipate. Otherwise, chlorine reacts with sodium in the soil, harming plant growth. Additionally, storing tap water in a container for a few days can help match the water temperature to the ambient temperature, eliminating temperature differences between water and soil and enhancing root water absorption.
(2) Soils and water in northern regions are mostly alkaline. Even if the potting soil is acidic, using alkaline water will cause the soil to become alkaline over time. Camellias are acid-loving plants and cannot survive in alkaline soil. To improve water quality, organic acids like lemon juice or vinegar (about 0.1%) or chemical acids like ferrous sulfate can be added to raise the pH and meet the plant's physiological needs. It is even better to combine this with liquid fertilizer, occasionally watering with diluted, fermented alum water or rice water, as these are more easily absorbed by camellia roots (see "Fertilizing" below).
Determining Watering Timing
Watering should vary with temperature changes throughout the seasons:
(1) Spring and Autumn: Water in the afternoon.
(2) Winter: Water around midday. At this time, the water temperature is closer to the soil temperature, benefiting plant growth.
(3) Summer: Water in the early morning or late evening. If watering only once a day, morning is better. Avoid watering with cold water during scorching midday. High temperatures cause rapid water evaporation from leaves, and sudden cold water can drastically lower soil temperature, slowing root water absorption while leaf transpiration continues, leading to "physiological drought," wilting, and even death of the entire plant.
Watering Techniques
(1) Each time, water thoroughly until water drips from the drainage holes at the bottom of the pot. Avoid partial watering.
(2) Sometimes, water may flow quickly from the drainage holes without fully wetting the soil. This occurs in two cases with the same cause:
- One: The potting soil is heavy clay, which may separate from the pot walls or crack due to excessive dryness, creating gaps for water to flow through.
- Two: The soil is loose, such as fine decomposed leaves, which shrink and create larger gaps when dry, causing water to runoff easily.
In such cases, first loosen the soil and block gaps, then use a fine watering can to slowly moisten the soil. After water drips from the bottom, water again thoroughly. For loose soil, water twice thoroughly (preferably with a fine watering can), wait 20-30 minutes to allow the soil to absorb moisture, and then water again thoroughly.
(3) If the plant wilts due to dehydration, do not water immediately with a large amount of water. Move it to a cool, sheltered place, mist the leaves, and lightly moisten the soil in the pot. Wait until the stems and leaves perk up before watering thoroughly. Excessive water at once can cause root damage, leaf drop, or even death.
In another case, if the soil is still moist but new leaves wilt, this is often caused by wind, sudden sunny weather after prolonged rain, or excessive dry air. Simply place the plant in a shaded, sheltered area and mist the leaves and ground. No watering of the soil is needed.
Moderate Fertilizing
Fertilizer is the source of nutrients for camellias. Camellias require dozens of elements, including carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, copper, zinc, boron, molybdenum, manganese, and chlorine. Among these, carbon, hydrogen, and oxygen can be obtained from water and air, while calcium, magnesium, sulfur, iron, and trace elements can be absorbed from the potting soil. However, nitrogen, phosphorus, and potassium are needed in large quantities, and their content in potting soil is often insufficient, requiring continuous fertilization.
- Nitrogen promotes stem and leaf growth. Sufficient nitrogen results in lush, dark green leaves, while insufficient nitrogen leads to sparse branches, small leaves, and yellowing. However, excessive nitrogen can cause excessive growth or even "burn" the plant, causing leaf drop.
- Phosphorus promotes root development, bud and flower formation, and enhances drought and cold resistance. Insufficient phosphorus inhibits growth, resulting in small flowers and early blooming or wilting.
- Potassium enhances photosynthesis, making stems and leaves strong and improving disease resistance and cold tolerance. Deficiency leads to weak, withered branches and leaves, making the plant susceptible to diseases.