Last updated on October 12th, 2021
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Having a long, bare, sunflower stalk in your garden without a bloom on top is beyond disheartening. But don’t worry. Several of the reasons we discuss for this problem can be fixed (not enough sunlight or time, for example) but others (e.g. damage) mean that you have to regretfully say goodbye to your hopes of the plant blooming.
Are you giving your sunflowers enough time?
Nature can’t be hurried. Everything has its own life cycle and schedule, and that includes sunflowers. Different varieties have different times to maturation, so check the information for your sunflower. Even though sunflowers in general are fast growing, they still need time to develop properly.
On average, sunflowers take 10 days or so for the planted seeds to germinate; another 20 days for the leaf and plant to develop brings us up to 35 days total so far; and the buds can take up to 30 days to grow; for a grand total of 65 days before the flower begins to open for pollination to occur. After this the flowers need about 20 days to fully open before the 35 days the seeds need to develop; they then ripen for the last 15 days or so of the sunflower’s life cycle. That’s a total of around 125 days.
Sit back, watch and wait for the flower bud to appear and take good care of the plant in the meantime.
Are your sunflowers getting enough sun?
Aside from impatience, this is the most common reason that sunflowers don’t bloom. These plants need at least six hours of full, direct sunlight, especially in the morning for mature plants. Too little sun or lots of hours of bright but indirect sunlight may slow or stop the formation of the flower bud.
Try cutting back any other plants that are shielding your sunflower or consider transplanting it to another, sunnier location.
Is there enough time left in the sunflower’s growing season?
If your sunflower’s growing information says that it takes 80 days to reach maturity and you plant it when there are only 45 days left in the growing season before the weather turns cold, it will never develop the flower bud. The plant will die before it has enough strength, energy and time to form the bud. Remember that it’s trying its best as the plant’s purpose is to grow, form a flower and then seeds to start the next cycle of plants.
There’s nothing you can do about this but read the seed planting instructions more carefully next year.
Is your sunflower stressed out?
Sunflowers are happy in well-drained soils that are kept moist. Although they don’t need fertiliser to bloom, they expect the soil to have an adequate supply of the nutrients they need. Anything other than these conditions, plus too little direct sunlight, stresses the plant and weakens it. In this state, it may fall prey to insect infestation or disease and this affects its ability to develop fully. This is a common reason why sunflower blooms do not appear.
Fertilise the soil, change your watering schedule and try and get more sunlight to the plant.
Is the tip of the stem damaged?
Sunflowers grow their blooms on the end of long stems – one bloom to one stem. If the tiny flower bud on the end of the stem is damaged or removed (by you, the weather, birds or other wildlife) a replacement one doesn’t form. The plant has to grow a whole new stem to produce a new flower bud. Check the very tip of the stem to see if there are any signs that there was once a little bud there that’s now absent or damaged.
There’s nothing to do here but take extra care of your other healthy sunflowers.
Once you got them sunflowers flowering you can read my guide on how to harvest sunflower seeds which you can feed to the birds, grow more sunflowers or even roast them to eat.