Should cosmos be cut back?
You should pinch out the growing tips of cosmos to encourage branching and flowering, and in around 12 weeks you should see your first blooms. If you then want to enjoy those flowers in the house as well as in the garden, cosmos make excellent cut flowers.
Of all the annual flowering plants you can grow in your cutting garden (or even the back of your veggie patch), none is more productive than cosmos. They truly are a cut-and-come-again flower: The more you harvest them, the more they bloom.
Cut your cosmos as the flower just opens and the center is still tight. Use sharp scissors to cut the slender stems at a leaf node — that's the spot where the leaf joins the stem. The plant will branch from there and form even more flowering stems.
Trimming & Pruning: Keep Cosmos trimmed of spent blossoms, to encourage new growth and continuous buds. During mid-summer, instead of just removing the blossoms when deadheading, trim the branches back to a third of the way down the plant; water and wait for a new crop for a late season display.
As soon as the first frost blackens the leaves, cut off the stems and foliage, lift them, remove all soil from the roots and dry them for a few days in a frost-free shed. Then pack the tubers in pots or a seed tray in vermiculite or used potting compost and put them somewhere dark and cool.
Pinch out Cosmos early in the season to encourage them to form a bushier growth habit and produce even more flowers. In addition, pruning Cosmos after their summer bloom can cause them to re-bloom in the fall.
At the end of the season, collect seed from flowering cosmos and save it to sow the following spring.
You can prevent leggy seedlings by providing natural light, artificial light and mimicking the weather using your hand or a fan. Cosmos seedlings can tolerate temperatures to a minimum of 57.2 Fahrenheit (14°C) Space your seedlings out once planted outside between 12-15 inches. Cosmos can grow as tall as 3ft.
To promote flowering you should transplant your cosmos as soon as possible to a sunnier location, cut back any overhanging tree limbs that could be casting shade or if its not too late in the Summer, sow new seedlings in a garden boarder with full sun and well draining soil.
Nearly all cosmos are annuals meaning they do not come back every year. In order to have blooms every year, you will need to resow the seeds the following spring. The only exception to this rule is chocolate cosmos, Cosmos atrosanguineus, which is grown like a dahlia from a tuber and is a perennial.
What do you do with cosmos in autumn?
Cosmos atrosanguineus or chocolate Cosmos flower is a tender perennial, meaning that its tubers should be lifted in the autumn and kept in a dry shed over winter or protected from the frost and cold weather by covering with straw, mulch or wrapped in horticultural fleece.
As you plant the Cosmos plants into the garden it is advisable to pinch out the growing tip of each stem. Pinching out involves squeezing the growing tip off between your finger and thumb. This reduces the plant size and will encourage the plant to grow side shoots giving bushy growth.
The perennial chocolate cosmos varieties will need winter protection. Place them in pots until they've finished flowering, then shelter over winter in a frost-free place until spring.
Place the packet in the bottom of a canning jar or clean mayonnaise jar. Place the seed envelope in the jar, put on the lid, and store it until next spring. The dried milk powder will absorb any stray moisture, keeping the cosmos seeds dry and safe until spring planting. Did you find this helpful?
Both germination and growth are fast, but cosmos plants are frost tender, so don't be in a rush. Cosmos are light sensitive and don't bloom their best until late summer, when the days grow shorter.
Flowers Falling Over
Because cosmos can grow to be tall, the flower heads can cause the flower to lean over. Again, cosmos plants can become quite large! Some varieties can grow as tall as 7 feet!
It will grow in any type of soil, but choose a plot with good drainage to avoid the risk of root and stem rot. Tall varieties may benefit from wind protection. Cosmos is a heat-loving plant and does best above 60°F(16°C). Below 55°F(13°C), growth and flowering are inhibited.
Cosmos don't like the cold. The annual plants are frost tender, which means frost will kill the plants; so if you grow from seed, don't sow them too early. April is early enough and gives them time to grow on before you plant them outside after the last frost of winter.
Giving them too much help in the way of fertilizer can make them overly tall and lanky. Instead of fertilizing them during the growing season, just mix some compost into the soil before you sow your seeds or set in your transplants, and your fertilizing is done!
Benefits: Better Blooms, More Colorful Blooms, Easy to Use
If you go to any farm or farmer's market the only type of fertilizer they will recommend using is this water-soluble solution by miracle-gro.
What fertilizer do cosmos like?
Do not fertilize cosmos. Nutrient rich soil produces plants that are weak-stemmed (floppy), late blooming and flower sparsely. Avoid soil that have been heavily amended with fertilizer and compost.
Cosmos are half-hardy annuals that grow, flower, set seed and die all in one year, but unlike hardy annuals, they can't withstand low temperatures. They're quick and easy to grow from seed, flowering in as little as 12 weeks, and can be added to borders and pots for a burst of showy colour.
Cosmos is an easy-to-grow flower that can reseed itself and grow in hot, dry conditions, making it a good choice for North Carolina gardens. The hardy annuals will give you blooms from summer to frost.
Cosmos are easy to care for, germinate, and will self-seed for the following growing season.
To deadhead means to remove spent blooms. As you see cosmos flowers start to fade, pinch or cut them back. The life cycle of a flowering plant ends in setting seeds. By removing the spent blooms, you set the cycle back and trick the plant into creating more flowers so it can get back to seed setting.
The perennial chocolate cosmos varieties will need winter protection. Place them in pots until they've finished flowering, then shelter over winter in a frost-free place until spring.
A seedling straining for light may grow leggy. When transplanting seedlings (either potting on or planting outdoors in pots and borders), I advise pinching out the growing tip of each stem to encourage stems to branch and produce more cosmos flowers.
Cosmos are not hardy plants and if you leave them in your borders over winter there is a real chance they will be killed by a sharp frost, or rot in cold wet soil. When deadheading, cut the stem back to the first leaf beneath the flowerhead. The perennial chocolate cosmos varieties will need winter protection.
As you plant the Cosmos plants into the garden it is advisable to pinch out the growing tip of each stem. Pinching out involves squeezing the growing tip off between your finger and thumb. This reduces the plant size and will encourage the plant to grow side shoots giving bushy growth.
To promote flowering you should transplant your cosmos as soon as possible to a sunnier location, cut back any overhanging tree limbs that could be casting shade or if its not too late in the Summer, sow new seedlings in a garden boarder with full sun and well draining soil.
Will cosmos reseed themselves?
Cosmos is an easy-to-grow flower that can reseed itself and grow in hot, dry conditions, making it a good choice for North Carolina gardens. The hardy annuals will give you blooms from summer to frost.
Cosmos are half-hardy annuals that grow, flower, set seed and die all in one year, but unlike hardy annuals, they can't withstand low temperatures. They're quick and easy to grow from seed, flowering in as little as 12 weeks, and can be added to borders and pots for a burst of showy colour.
