Sunflowers are hardy and can survive tough conditions. However, they draw a line regarding the amount of sunlight and water they need. Sunflowers need a lot of water in the first stages of growth and when flowering, but how long can they survive without water?
Sunflowers can last a week without water in the summer if they’ve established a deep root system. When they bloom, sunflowers can go for 20 days without water before showing signs of stress. However, sunflowers cannot go for long without water when flowering or developing roots.
Water is critical for sunflowers when they are developing tap roots. A healthy root system will support sunflowers in periods when they go without water. In this article, I’ll discuss how much water sunflowers need, when they need more water, and how long they can go without water.
Can Sunflowers Go Without Water?
Sunflowers need a lot of water to support their root growth. Some sunflower varieties grow 12 feet (3.66 m) tall and need a strong root system and stem base to support large flower heads, measuring 4-12 inches (10-30 cm). Some cultivated sunflowers only have one head, while some varieties have up to 20 heads per plant.
Sunflowers can go without water after their roots are established and after they flower. However, when they go without water, it’s for a limited period. Before flowering, the sunflower can go for a few days without water. After the flower matures, sunflowers can go up to 20 days without water.
When sunflowers go without water, you need to observe the plants keenly. Sunflowers are resilient and drought resistant because they have deep tap roots. However, they need water when the leaves start wilting and the flowers droop.
Sunflower Water Needs
A sunflower’s demand for water varies depending on the stage of growth. There are times when you need to water regularly, while other times, you need to give the flowers a break.
Overwatering and underwatering affect sunflowers, so you need to know how much water to give your sunflowers at different stages.
| Sunflower seedlings | Water regularly, but lightly. Ensure the soil remains moist as the seeds germinate. |
| Transplanted seedlings | Water deeply (2 gallons/7.57 liters weekly) around the root zone to encourage deep root development. Water daily until the sunflower is 2 feet (61cm) tall. As the plant grows, widen the watering area to about 6-12 inches (15.24-30.48cm) around the plant. |
| Sunflowers with established roots | Supply an inch (2.54cm) of water weekly. Sunflowers can go for a few days or a week without water. Water when the top 2 inches (5.08cm) of soil are dry. Water daily when it starts flowering. Water the base and spray the flower to keep the head moist and wash away dust. When the flowers bloom to full size, change the watering schedule to once a week. |
Sunflowers usually show signs of water stress when they go for 20 days without water before they bloom and 20 days after they bloom. This is a critical period for sunflowers, and you need to ensure they get adequate water to support the plant’s demand.
Mature sunflowers can go for longer without water because they have deep roots to sustain the plants. However, growing sunflowers are needier and can only go a few days without water before they start showing signs of stress.
This YouTube video analyzes the sunflowers’ water needs. It also highlights the factors that influence how much water to give sunflowers at different stages:
How and When To Water Sunflowers
When you overwater sunflowers, they’ll start rotting, and when you underwater them, they’ll start wilting. Therefore, you need to find a balance where the sunflowers get the water they need and the right quantity.
Once established, sunflowers have roots that extend to about 1.5 feet (45.72cm) downwards and 1.5 feet (45.72cm) outwards. These roots allow sunflowers to go for brief periods without water. However, for best growth, sunflowers need consistently moist soils.
An inch (2.54cm) of water per week is enough to keep at least 6 inches (15.24cm) of soil moist.
Here are tips on how and when to water sunflowers:
- Water the soil directly. Overhead watering will get the flower head and foliage wet, but it doesn’t guarantee the water will get to the roots.
- Water sunflowers early in the morning to allow the roots to absorb as much water before the sun comes up. This allows the plant to absorb the water before it gets too hot.
- The water around the root base extends outwards as the plant grows. This ensures you cover the root growth. Alternatively, you can water the base until you create a pool. This will ensure the vast root system gets sufficient water to support the entire plant.
- Quick-draining soils, such as sandy soil, will not hold enough moisture. You need to water more frequently.
- Use mulch during the dry season to keep the soil moist and reduce water loss through evaporation. You will also be saved from the strain of watering your sunflowers too frequently, especially if they start drooping.
- Sunflowers growing in pots need to be watered more because they dry out quicker. However, you should avoid overwatering because the roots may rot.
- Avoid blasting the flower head when using a hose. You may damage the florets and wash away pollen.
- If water sits in your garden for some time, add compost or create drainage holes. This is especially important during the rainy seasons, as water pools may cause the stem base to rot.
- Check the soil before watering your sunflowers. If the soil appears moist, it is best to wait another day or two before watering.
- If you are expecting some rain, hold out on watering your sunflowers. Even if it doesn’t rain, your sunflowers can survive a few days without water.
- After the sunflower gets to 2 feet (0.61 m) tall, reduce the watering schedule and the amount of water you use. This is a good sign that you’re watering correctly, and you don’t want to risk overwatering.
- If the sunflowers start wilting or turning brown before they mature, you are underwatering. It’s essential to keep an eye on your sunflowers for any sign of over or underwatering.
- Avoid watering the sunflowers once the head turns down and allow the seeds to dry out. The head facing down is a sign of the end of the flower’s growth cycle.
Suppose you’re a visual learner; I recommend watching my YouTube video on how long sunflowers last without water. I’ll walk you through the amounts of water sunflowers need at different growth stages. So definitely give the video a watch if you want to learn more about the watering needs of sunflowers.
Sunflower Varieties
There are at least 70 sunflower varieties. Some come in different colors, and they grow to different heights. Others only have one flower at the apex, while some of the recent varieties have branches with at least 20 flower heads.
Taller sunflowers tend to have deeper roots and are more drought-resistant. However, all sunflowers need plenty of sun and water.
While each variety has its unique traits, it’s important to note that the taller the sunflower is, the deeper the roots are. And the deeper the roots are, the more water it needs in the initial stages of growth.
The roots of the shorter sunflower varieties are shallow and need more water to sustain them, especially during the dry season. Sunflowers with deep roots can survive for long without water during a drought.
| Sunflower Variety | Height | Characteristics |
| Mammoth /Skyscraper | 12 feet (3.66m) | Large flowers (1 foot/30.48cm wide). Strong stems. High-quality sunflower seeds. Drought tolerant. Needs a lot of water to sustain its height. Water daily until it’s established. Give an inch (2.54cm) of water once or twice a week when roots are established. |
| Autumn beauty | 6 feet (1.82m) | Orange, red, and orange blooms. Flowers are 5 – 10 inches (12.7 – 25.4cm) wide. USDA Zones 3-9. It favors mass planting. Good for flower arrangements. Plant 2’’ (5.08cm) deep and 18’’ (45.72cm) apart. |
| Moulin Rouge | 5 – 7 feet (1.52 – 2.13m) | Dark red petals with a hint of yellow at the base. Blooms are 4’’ (10.16cm) wide. Polleness. Awesome for cutting flowers. |
| Teddy Bear Sunflowers | 4 – 5 feet (1.23m – 1.52m) | Fluffy deep yellow flowers 6 inches (15.24cm) wide. Dwarf sunflower is ideal for borders and containers. Plant ½ inch (1.27cm) deep. Water deeply (2”/5cm). Avoid overwatering. Only water at the base. Watering overhead will encourage diseases. |
| Sunrich Gold | 5 feet (1.52m) | Produces single flowers 4” – 6” (10.16cm – 15.24cm) wide. Polleness. Rich, golden-yellow petals, and green-yellow centers. |
If you’re interested in planting sunflowers, I’d recommend going with Mammoth Sunflowers as they grow easily, are drought tolerant, and have a high germination rate.
This sunflower type is ideal for USDA Zones 1-10, and the huge blooms are about 10’’-12’’ (25.4cm-30.48cm) wide. While these flowers can reach a height of 12 feet (3.66m), it can take 110 days for the seeds to bloom.
This YouTube video is a great guide on some of the sunflower varieties and how to grow them:
Conclusion
Although sunflowers have a strict watering schedule from the moment you sow the seeds to when the flowers mature, there are exceptions to the rules.
- Water sunflowers more often when it’s hot and dry outside.
- You may need to water sunflowers more often than the other flowers in your garden.
- Confirm if the soil is dry before watering.
- To reduce moisture loss, mulch the soil but avoid the stalk.
- Sunflower seeds need to have moist soil until they germinate.
So, while sunflowers can survive up to 20 days without water, it’s essential to keep an eye on the soil conditions.
