1. Soil and pH Needs
Celosia is easy to grow in moist, well-drained, fertile soil and prefers full sun. They do not perform well in wet, poorly drained soils. Heavy clay soils will retard root growth and starve the plant of oxygen, which can lead to root diseases. Soil should be amended with fully composted organic matter prior to planting and in the case of clay soils the addition of Canadian sphagnum peat moss and well-rotted compost are good sources of organic matter that will aid in aeration. If possible, incorporate two to three inches of organic matter into the top six inches of soil. If adding organic matter, be aware that organic matter that has not been fully composted will tie up nitrogen and sulfur leading to nutrient deficiencies and poor growth. Soil pH should be 5.5 – 7.0 for optimum growth; and should be tested prior to planting but after adding any amendments. This can be done quite easily with a portable pH tester. Mix one part soil with two parts distilled water, stir well and wait thirty minutes, then follow the instructions for using the pH meter. If pH is too low, the addition of lime is warranted. However, the rate will vary depending on how much you need to raise the pH and the type of soil you are dealing with. Clay soils or those with a lot of organic material have a high buffer capacity and require more lime than sandy soils, which have a low buffering capacity. A good soil testing lab can determine the lime requirement index (LRI) of your particular soil and can recommend types and rates of lime to use. The frequency of watering will depend on the type of soil, weather conditions and the amount of mulch. Mulch will not only reduce soil water evaporation but will also reduce splashing of water onto the lower leaves, moderate soil temperatures and reduce weed competition. Because they're quite drought-tolerant, Celosia seldom need daily watering; in prolonged periods of drought, however, watch that the soil doesn't get too dry.
Celosias are light to moderate feeders in the landscape; and can have a crop life of three-four months. An application of a balanced controlled-release fertilizer (CRF) such as 10-10-10 or 14-14-14 with a 3-4 month formulation applied to the bed at planting will keep the plants well fed, depending on the amount of irrigation required and the average daily temperature. In areas of high irrigation and high temperatures it may be better to use a formulation with a slower release rate since higher temperatures will cause the fertilizer to be released quickly. In high pH soils (alkaline soils) additional iron or iron sulfate may be beneficial to reduce chlorosis (yellowing) of the foliage. Yellow foliage on Celosias may also be caused by a nitrogen deficiency within the plant. Both can be corrected with the proper supplemental fertilizers.
Celosias are prone to several diseases which may be seen in the landscape. Powdery mildew is the result of overhead irrigation, improper plant spacing, poor air circulation, or watering too late in the day. It can be avoided by employing proper cultural practices. A plant with powdery mildew will have white fungal growth on the upper surface of the leaves and it may also form on the flowers. Rhizoctonia is also common on Celosia. Symptoms include wilting and death, especially of seedlings (damping off). Moist brown lesions commonly form at the base of infected petioles or on lower stems, usually at the soil line. Crown areas decay, and roots are also sometimes infected and become dark and decayed, especially in peat-containing mixes. Rhizoctonia root rot is favored by relatively high temperatures and intermediate moisture, neither too wet nor too dry. To help control foliar diseases, avoid wetting foliage and provide adequate air circulation between the plants. If overhead irrigation is used, water early in the day to allow foliage to dry before nightfall.
There are several pests that you may find on Celosia: aphids and mites. Spider mites feed on the underside of the leaves which causes yellow spots to form. This results in decreased plant growth and production. The nymphs and adults produce webbing that can cause cosmetic damage to the crop. Aphids feed on the plant sap. This halts growth, causing the leaves to become deformed. Aphids also excrete honeydew which causes sooty mold to develop and makes the plant unsightly. Healthy, vigorous plants are less susceptible to pest damage than unhealthy plants.
5. Tips for Success
- Celosia prefers full sun, and a well-drained soil.
- Pinch back early blooms which will result in more branching and flowers
- Celosias have moderate drought tolerance.
- Remove weeds from the plantings that compete with Celosia for moisture, nutrients and light.