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How Much Water Do Sunflowers Need? | Growgardener Blog!

Did you know that sunflowers are more than just vibrant and showy flower heads? These hardy plants are also packed with nutritious seeds that offer various health benefits.

However, most people only use them for ornamental purposes.

Sunflowers are highly adaptable, can grow in various environments, and attract butterflies, bees, and other pollinators to the gardens.

If you have some sunflowers growing in your garden, you must give your best to keep them healthy. Water is a critical factor affecting sunflowers’ growth and development, which often confuses many growers, leaving them to wonder, “How much water do sunflowers need?”

If you are also one of the curious ones, it’s time to put your curiosity aside!

Today in this article, we will review how much water sunflowers need and which factors affect their water requirements.

So without wasting any more time, let’s begin!

How Much Water Do Sunflowers Need
How much water do sunflowers need? – Image via Sharon Pittaway.

How Much Water Do Sunflowers Need?

Sunflowers typically need about 1 to 1.5 inches (2.5–4 cm) of water per week.

Still, the exact amount of water depends on several factors, including:

  • Sunlight
  • Weather
  • Soil
  • Age and size of the plant, and
  • Humidity

Sunflowers need unswerving moisture to grow strong roots, leaves, and beautiful flowers and seeds.

They have a higher growth rate and can grow up to 16 feet tall!

So, they need adequate fuel (water and sunlight) to support their growth.

How Often Should You Water Your Sunflowers?

Here are some points to keep in mind.

  • Watering early sunflowers frequently keeps the soil moist until the seeds germinate. (The germination process usually takes about 1–2 weeks.)

Growgardener Note: Sunflowers need more frequent watering sessions during germination because they have deep root systems supporting bulky stems and giant flowers.

  • Once deep and solid roots are established, sunflowers can survive several days up to a week without water in hot summer weather.
  • You have to avoid water stress a few days before and after blooming; it helps the roots to grow more robust.
  • During hot and dry weather, you may need to water your plant more often to prevent wilting.
  • And yeah, in the rainy season, avoid supplemental watering. Do not let the plant sit permanently in wet soil—it leads to water overload.

That’s all!

How to Water Your Sunflowers?

Sunflowers are more susceptible to fungal and mold diseases and hate waterlogged soil as it deteriorates their growth.

Thus, never let water sit deep in the soil and ensure proper drainage.

That brings out a question of how to water sunflowers.

How to Water?

The method for watering the sunflowers is slightly different.

Watering the base is better than sprinkling water over the flowers.

Here are some “Do not’s” you should keep in mind while watering your sunflowers:

  • Do not let the soil dry out completely, as sunflowers require consistent moisture to thrive.
  • Avoid watering sunflowers during harsh sunlight since water droplets can function as magnifiers, concentrating the sun’s heat onto the plant and potentially causing damage.
  • Do not water sunflowers if the soil is still moist; over-watering can lead to root rot and other problems.
  • Do not water the flower heads directly to prevent damage and loss of pollen.
  • Avoid watering sunflowers after sufficient rain.

Now, let’s look at the appropriate time to water sunflowers.

Appropriate Time to Water Sunflowers!

Like other flowers, the best time to water sunflowers is early morning before sunrise. On the other hand, you can also water them in the evening, but it may increase the risk of fungal growth as the leaves and soil may stay wet overnight.

Sunflowers don’t like shady and wet environments. Thus, they do not require daily watering sessions.

You must check for water 1–2 times per week to ensure the healthy growth of your flower.

So, to keep your sunflower healthy, water them profoundly but infrequently—allow the soil to dry out slightly in between waterings.

That said, it’s time to look at different factors affecting the watering requirements of sunflowers.

How Much Water Do Sunflowers Need
These back-lit sunflowers would have been pretty enough, but it was the way the water from the sprinkler – via Flickr

Which Factors Affect Sunflowers’ Water Requirement?

If you are fond of gardening, you will likely be prone to overwater your plants.

But is that okay?

No, of course not!

Watering your plants like a pro is only possible if you keep some factors in mind that can affect your plant’s water requirements.

For sunflowers, these include:


As their name suggests, sunflowers love sunlight.

They like direct sun exposure for about 4–5 hours daily.

However, too much sunlight increases transpiration and leads to significant water loss, requiring more frequent watering to maintain adequate moisture levels.

Therefore, you’ll need to water them more often.


Sunflowers are native to areas with warm climates and prefer temperatures between 65°F to 85°F.

That means these plants like moderate to high temperatures but cannot tolerate extreme heat or cold.

Given their preference for warm climates, it’s essential to consider how weather conditions can affect their water requirements.

So, the question is, how does the weather impact the water needs of sunflowers?

Let me explain this through an example:

If it is the rainy season, you don’t have to water your sunflowers because the rain will quench their thirst. In contrast, sunflowers require frequent watering during hot weather to maintain adequate soil moisture levels.


The type of soil in which sunflowers grow also influences their water needs. Well-draining soil retains less water and may require more frequent watering.

On the other hand, adding organic matter such as compost or manure to the soil can improve its structure and overall water retention, reducing the need for frequent watering.

Growth Stage and Size

Sunflowers have different water requirements during different growth stages.

As I mentioned before, sunflowers need more frequent watering during germination and less once established. Moreover, sunflowers need more water during the flowering and development stages than in the vegetative growth stage.

But what about the size of the plant?

Larger sunflower plants with big flower heads require more water to flourish. As the sunflowers grow taller, they produce more leaves and flowers, increasing their water requirements.


Like all other factors, humidity also affects the water requirements of the sunflowers.

Your sunflowers will require less frequent watering if you live in an area with high humidity. In contrast, they’ll need more frequent watering in dry climates.

How to Check If Your Sunflowers Need Water?

Watering sunflowers primarily aims to keep the top 6 inches of soil moist.

  • Monitor your plant 2–3 times a week and give them sufficient water in hot and dry weather.
  • If it rains, keep an eye on your plants to see if they need more water—in the case of sunflowers, they usually don’t.

But how can you determine that the soil needs water?

Here is a way,

  • Dig your finger into the soil to feel the moisture.
  • If the top few inches of the soil feel dry, it’s time to water your sunflowers.

Just make sure you do not overwater your sunflower, as it can cause waterlogging.

Consequences of Overwatering Your Sunflowers!

Overwatering is the worst thing you can do to your sunflowers because these plants are more prone to fungal diseases and root rot.

Here are some disadvantages of overwatering sunflowers:

  • Root rot is expected if the roots remain in a water pool for extended periods.
  • Nutrient imbalance can occur as excess nitrogen prevents the plant from forming flowers.

Growgardener Note: When plants are overwatered, the soil becomes waterlogged, which results in decreased oxygen levels. This leads to decreased microbial activity, which can cause excess nitrogen buildup in the soil.

  • The leaves turn yellow due to overwatering and nutrient deficiency, and your plant might die out.
  • Wilting leaves are thought to be the signs of dehydration but can also be caused by excess moisture.
  • Wet soil can lead to root injury and hinder the plant’s ability to absorb water and nutrients.

How to check if you overwatered your sunflower plant?

  • Dig the soil and take out a handful of it.
  • Squeeze it with some force.
  • If it makes a firm ball or feels overly wet and slimy, it is a sign of overwatering.

In that case, you must reduce or stop watering for some time.

Only water your plant when the soil feels dry.

How Much Water Do Sunflowers Need - Person Watering Sunflowers
Person Watering Sunflowers | Image via Shutterstock.

How Can You Prevent Overwatering?

The simple and effective strategy for saving your sunflowers is to water less frequently.

  • Stop supplemental watering in the rainy season.
  • Try to remove mulch to increase the evaporation rate.
  • Place your plant in a windy area.
  • In summer, 1 inch of water per week is sufficient; in winter, ½ inch is adequate.
  • Let the soil dry between 2 watering sessions.

That’s all!


So, how much water do sunflowers need? I hope you now have the answer.

Sunflowers usually need about 1 to 1.5 inches of water per week, but it depends on external factors like temperature, sunlight, and soil.

While watering, follow a proper watering schedule, as underwatering and overwatering are both harmful to your sunflowers.

I hope you liked today’s article!

If you find this post helpful, don’t forget to share it with people.

Moiz Atiq.