The question of how much water does a sunflower need a day, isn’t a straightforward one to answer as it depends on a number of factors.
What stage of the growth cycle is it at? Where is it being grown? What are the soil conditions like? And more…
Nevertheless ensuring a sunflower gets enough water each day is still a concern for any gardener, especially if you are growing the plant for the first time.
So let’s try and address the topic of sunflower water requirements.
How Much Water Does a Sunflower Need a Day?
When sunflower seeds are germinating they should be watered frequently, at least every couple of days, so the soil is kept consistently moist, but not soaking wet. Once they have matured it is recommended they are watered once a week with enough water to keep the top few inches of the soil moist. Around 2 gallons (7.6 liters) should be sufficient.
How Often Should You Water Sunflowers?
When I was jotting down my thoughts for this article initially I was just going to go over my personal experience with growing sunflowers and the amount of water I have found they need.
But then I thought, whilst my personal experience is good to use, why not draw upon the knowledge of a number of experts rather than just me (if I dare to call myself an expert!).
So that is what I have done.
So let’s look at some common conceptions of how much water sunflowers need from those in the know
Expert #1: Sonali Bahunguna, Horticulturist
Sonali notes that sunflowers need more water than most plants and that it is important to ensure the soil remains moist and well-drained.
He recommends ensuring sunflowers receive at least 7.6l of water a week whilst they are germinating.
During the growing season, Sonali suggests around an inch of water per week.
Expert #2: Fiona Reyes, gardening blogger for gardeninghow.com
Fiona breaks the watering process down into three parts: germination, early stages of growth and established sunflowers.
She notes that when sunflower seeds are germinating they require a lot of water and recommends watering seedlings every couple of days or more regularly if it is hot and dry.
As the seeds grow into tiny seedlings Fiona recommends you continue to water them daily around the root zone.
Once they are established, she notes the hardiness of sunflowers and the fact less water is required. She advocates watering deeply either once a week or if the top two inches of soil is dry, with at least 2 gallons (7.6 liters) to encourage deep root growth.
Expert #3: Pamela Anne from SheSaidSunflower.com
Pamela Anne also recommends 2 gallons (7.6 liters) of water a week for sunflowers, and more during their early stages of growth. She equates this to around 1 to 1.5 inches (2.5 to 4cm) of rainfall per week.
Pamela Anne is a strong advocate of establishing a daily watering routine for sunflowers until they are around 2 feet (61cm) in height.
If your sunflowers are planted outside she believes a solid downpour of rain three times a week is sufficient for them to grow well.
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If you live in an area with little rain Pamela Anne’s advice, up until your sunflowers reach 2 feet (61cm) in height, is to water them daily and sufficiently until the water pools.
After this she says to water them if there are a day or two of full sun and no rain, watering around 6 to 12 inches around the plant so it reaches the root system.
If you are growing your sunflowers in pots to start with Pamela Anna says watering daily is very important.
Expert #4: Shelley Frost and Victoria Lee Blackstone from Hunker.com
Hunker break the watering process down into starting sunflowers, established sunflowers and sunflowers being grown in pots
They note the importance of light and frequent watering for germinating sunflower seeds to keep the soil consistently moist until the seeds germinate.
As sunflowers develop their strong and deep roots and become established, Hunker advises they can usually go several days to a week in the heat of summer with no water. They recommend ensuring one inch of water per week during this time.
When watering to supplement rainfall they suggest several gallons once a week, with the goal of ensuring sufficient water to moisten the top six inches of the soil.
Expert #5: Anna from MyGardenFlowers.com
Anna is another to reiterate the importance of ensuring sunflowers get more water during the germination phase.
She notes that seedlings need to be watered every couple of days, whilst mature sunflowers only need water once a week.
For seedlings, she favors watering every couple of days and more often if there is a dry, warm spell, keeping the soil damp but not sopping wet.
For mature sunflowers, Anna says around one inch of water a week should be fine, which she says is the equivalent of a 10 to 20-minute drip soaking with a hose. Soil should be damp, but not muddy.
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Expert #6: Sarah Lariviere, SFGate.com
Sarah is another who breaks the watering process into seedlings and mature sunflowers.
She too says seedlings should be watered every couple of days, or more often if it is particularly dry and hot. The soil around newly planted seeds should be kept evenly moist.
Mature sunflowers can adapt to drier conditions she notes. If it is very dry she too suggests placing a hose near the base of the sunflowers and drip-feeding water for around 20 minutes, or until the ground is moist but not muddy.
Expert #7: Marcel, Plantophiles.com
As an overview, Marcel says sunflowers need watering at least twice a week and require at least two gallons (7.6liters) when doing so.
He points to the fact that it is estimated sunflowers need around 34 inches of water a week for optimal growth.
He is another who says the soil around a sunflower should never be dry, but damp or moist to the touch, however it shouldn’t be soaking wet.
For germinating sunflower seeds he reiterates the importance of keeping soil moister than when a sunflower is growing above ground. This is because it doesn’t have the roots to find moisture underground. So he calls for frequent watering, but with a light hand.
He also suggests that potted sunflowers require more watering as they are not able to find moisture underground.
An Overview of What the Experts Say
I know there is a lot of information there, so let’s try and summarise what has been said:
Expert #1: Sonali Bahunguna, Horticulturist
- Germination: Two gallons (7.6l) of water a week (1.1l per day)
- Mature sunflowers: One inch of water per week
Expert #2: Fiona Reyes from GardeningHow.com
- Germination: Water every couple of days or more if hot and dry
- Mature sunflowers: Two gallons (7.6l) once a week (1.1l per day)
Expert #3: Pamela Anne from SheSaidSunflower.com
- Germination/up until 2 feet high: Water daily until the water pools
- After 2 feet high: Water 6 to 12 inches around the roots if you go a couple of days with full sun and no rain.
Expert #4: Shelley Frost and Victoria Lee Blackstone from Hunker.com
- Germination: light, frequent watering to keep the soil moist
- Mature sunflowers: One inch of water per week
Expert #5: Anna from MyGardenFlowers.com
- Germination: Water every couple of days or more often is hot and dry
- Mature sunflowers: One inch of water per week
Expert #6: Sarah Lariviere, SFGate.com
- Germination: Water every couple of days or more often is hot and dry
- Mature sunflowers: Enough to keep soil moist but not muddy
Expert #7: Marcel, Plantophiles.com
- Germination: Frequent water, but with a light hand
- Mature sunflowers: Regularly enough to keep soil damp or moist to the touch
How Do You Know When a Sunflower Needs Watering?
If you are still not sure if your sunflower needs watering, the easiest thing to do is keep an eye on the soil and your sunflower itself.
If the soil surrounding your sunflower appears dry, crumbly and dusty it is in need of some water.
Likewise, if your sunflower appears to be drooping this is another tell-tale sign it needs some water.
Can You Overwater a Sunflower?
Overwatering a sunflower can be just as harmful as underwatering.
Excessive watering can mean the roots of a sunflower become so soaked and soggy it leads to disease, mould and root rot.
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Signs of overwatering can include yellowing of its leaves and brown rot at the base of the stem.
Keep an eye out for puddles or standing water around your sunflower, this could be a sign of heavily compacted soil that isn’t draining properly.
Final Thoughts
The answer to the question of how much water does a sunflower need a day isn’t totally cut and dry (pun slightly intended).
However, as you can see, all the experts agree that when sunflower seeds are germinating they need to be watered much more frequently.
Once they are established they have mature root systems and can seek out water in the soil more easily, and therefore it is not so important you water them regularly. Just an inch of water a week can be sufficient.
There will of course be slight variations depending upon the weather conditions where you live and the soil conditions you are growing them in. But follow the above guidelines and you will be broadly ok.
