Celosia are dazzling and popular members of the amaranth family, grown as garden annuals in most of the United States. They are a great addition to a summer garden to add texture and eye-catching brightness. Species and cultivars are available in an array of forms, colors and heights. You can find Celosia from six inches to 3 feet tall, in pastels and hot, vivid hues, to fit the requirements of a front of border delight, feathery vertical accent or long-lasting cut flower.
There is some disagreement about properly naming these plants botanically. The plants available to gardeners are most easily identified by their common names including plumed type (Celosia argentea Plumosa Group), crested or cockscomb type (Celosia argentea Cristata Group) and wheat type (Deeringia spicata syn.Celosia spicata). Some plants are hybrids of more than one species.
These warmth-loving, summer bloomers are most successful when grown in full sun and highly fertile, fast-draining soil.
Sensitive to cold, your Celosia should be introduced to the garden only after night temperatures are reliably in the upper 50’s. Prepare the garden by incorporating organic compost into the soil to enhance nutrition and drainage. Poorly draining soil can kill your plants so improve before planting! Mix a slow-release balanced fertilizer into the planting area as well, taking care not to let it pool in the planting hole where concentrated amounts may burn tender roots.
Be gentle as you transfer your plants into the garden bed; they resent disturbance and a little care will help get them off to the right start. Allow each plant plenty of space. Check how large your plant will grow and space accordingly so that plants do not compete and reduce the amount of flowers produced. Well-spaced plants will have fewer issues with diseases and foliage deterioration.
You can also pinch back new growth to create a bushier plant at the early stages of growth. This works particularly well with for plume and cockscomb type Celosia which are naturally branching plants.
Celosia may be planted in containers but will grow somewhat less successfully. Make sure that your container has a drain hole and lift it slightly off the ground with “pot feet” to improve drainage. Choose cultivars that grow less than 2 feet tall for this purpose.
Growing Celosia successfully requires strong, direct sunlight for 6 or more hours per day. Your plant will not produce those beautiful flowers without enough sun.
Too much water is often a problem for Celosia and can kill your plants. Let the top 1 to 2 inches of the soil dry before watering again. Water your plants in the morning, when they are actively photosynthesizing. Avoid wetting or splashing the leaves to reduce disease transmission and sunburn. Water needs will change with temperature, rainfall, humidity and sun so be attentive to conditions.
Highly organic soil is the best source of nutrition. In addition to the slow release fertilizer incorporated at the time of planting, you will need to feed your plant only once a month with a bloom-boosting fertilizer.
Celosia can bloom from June until frost. The flowers are tough, long-lasting and unlikely to fall off the plant after they die, so you will need to snip them off to keep the plant looking fresh. Deadheading your Celosia will also encourage new blooms. Remove the flowers as they start to turn brown and lose color by cutting back the stem to the next healthy set of leaves. If you wait too long, seed development starts and the plant puts its energy into that reproductive effort rather than new blooms. You can also remove dead or damaged stems at any time.
Some Celosia can seed themselves generously in your garden if you don't deadhead the flowers. This is particularly true of wheat type Celosia, with its profusion of flowers. Removing flowers before they seed can prevent the plant from becoming a nuisance and popping up in greater numbers than desired.
Celosia are tender and will die once temperatures drop into the 30 to 40° F. zone, or below. If they are planted in containers, they are even more exposed, as the roots are closer to the chilly air. If you live outside of USDA zones 10 – 12, your Celosia are very unlikely to survive the winter and, like all annual plants, will need to be replanted next year. You can cut your entire plant to the ground once it turns brown or loses its attractive qualities.
In zones 10 - 12, your plant has a good chance of regrowing in the spring. Cut back flowers but allow the leaves to remain on the plant until they die back; the energy they create during late season photosynthesis is beneficial to the health of the plant.
Celosia do not make successful houseplants if brought indoors at the end of the season.
Starting your seeds in plug cell garden trays will allow you to later transfer the seedlings to the garden with the least disturbance to sensitive roots. Fill the cells with moistened seed-starting medium and plant 3 seeds per cell about 6 weeks before the last frost date. (Refer to the instructions on your seed packet for the best timing information specific to the variety that you have selected to grow.) Gently cover seeds with a thin layer of vermiculite so that some light penetrates. Cover each tray of cells with plastic wrap and keep warm at 75 to 80ºF. Moisten soil from below so that it does not fully dry out but keep it on the dry side. Seeds should germinate in about two weeks after which they are prone to damping-off disease if conditions are too wet.
Keep the seedlings indoors, protected from spring chill, until night temperatures are reliably in the upper 50’s and the soil has warmed up. Remember that the roots dislike disturbance so handle seedling plugs delicately when it is time to transplant outdoors.
Celosia are great, long-lasting cut flowers but can also be dried for extended enjoyment. When you cut the flowers for either purpose, be sure to leave plenty of stems with foliage on the plant, to continue to photosynthesize and create new flowers. Cut when flowers are just fully formed but fresh for longest lasting display in a vase. Use a clean cutting tool, such as a knife or hand held pruners and cut the flowers in the early morning when they are most full of moisture. Condition immediately in a vase of cool water before arranging in fresh water. Add flower preservative to the water for prolonged life.
To dry the flowers, remove foliage after cutting and pat dry any water on the flowers. Bundle a bunch of freshly cut Celosia blooms and hang upside-down in a dark and dry space for about 3 weeks. When they are no longer soft they are ready for display.