Dahlias need some full sun, but fade quickly under excessive heat and bright sunlight. They cannot take daylong full sun without harm. For dahlias, 6 hours of sun is more than enough, although if temperatures are mild, 8 hours is not too much. Give your dahlias 6 hours of full sun, with as many of those hours as possible in the morning. Doing this will encourage your dahlias to flower during late summer and well into the fall.
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How Many Hours of Sun Do Dahlias Need?
Dahlias require 6 hours of full sun per day. You should try to ensure they receive this light in the morning, however. This is because intense, strong sunlight can cause heat damage to the delicate dahlia flowers. For this reason, consider planting your dahlias in an area where they will receive sun in the morning and shade in the afternoon.
- Dahlias need 6 hours of daily sun.
- Strong, intense sunlight may lead to heat damage.
- Shade your dahlias in the afternoon.
- Afternoon sun may damage your flowers, and they’ll take much longer to bloom.
If they receive too much afternoon sun, heat damage may cause dahlias to bloom very late in the year, thus shortening the length of time you have to enjoy their beauty.
Can Dahlias Grow in Indirect Sunlight?
Dahlias can grow in indirect sunlight and will not die or wilt. However, they do need sun to thrive. If no full, direct sun is provided, they will not reach their potential. Dahlias originated in Mexico, where warm weather and sun are commonplace. This means that—even though excessive direct sun can harm them—no direct sun can be just as bad in another way. Although dahlias grown in indirect sunlight still bloom on schedule, there will be fewer flowers and they will be smaller.
- Dahlias can grow in indirect sunlight.
- Blooms may be smaller and there may be fewer of them.
- Dahlias planted in indirect sunlight may reach an abnormal height.
In addition to fewer flowers, the dahlia plant itself may grow inordinately tall in its quest for sun. Because dahlias have a natural height of 5 feet (1.5 meters) and often need to be staked, you probably don’t want them growing even taller. The best remedy is to plant them where they get morning sun and indirect sunlight during the afternoon. Combine this strategy with our dahlia pruning tips to produce the best flowers possible.
Can Dahlias Grow in Shade?
You won’t be happy with the results if you attempt to grow your dahlias in shade. If they don’t receive enough sunlight, dahlias may be prone to fungal infections. Alternatively, they may develop mildew on the leaves and flowers. Dahlias grown in full shade may even fail to bloom.
- Dahlias won’t die in shade, but may not produce any flowers.
- Dahlias grown in shade do not have vibrant colors.
- Shaded dahlias are susceptible to fungus disease.
You have probably selected dahlias due to their beauty and color, which create a dramatic look in your garden. If you try to grow them in total shade, the color of your dahlias may be pale and appear almost faded, even if they do manage to bloom. Therefore, although they won’t typically die in shade, you won’t get the results you most likely want.
What Happens if Dahlias Don’t Get Enough Sun?
Like all flowers, dahlias must have some full sun so that photosynthesis can occur. While 6 hours per day is optimum, they can survive with less. However, dahlias that don’t get enough sunlight will produce smaller, less lush flowers.
- Dahlias may wilt if deprived of sun.
- Petals may drop before the season is over if dahlias don’t get adequate sun.
- Dahlias may not grow large blooms if sun-deprived.
Dahlias that don’t get enough sun typically wilt in a short length of time. Flower petals may fall prematurely as well. Morning sun is best for dahlias, as it gives the flowers adequate light to nourish themselves. By providing morning sun and afternoon shade you help prevent heat scorch or other problems that come from excessive sun exposure.
Can Dahlias Get Too Much Sun?
Oversunned dahlias may not bloom till very late in the season. They may also have a very short life once they are fully bloomed. Sun scorch is another possibility you want to avoid. This is evidenced by browning and curling of the leaves and the flower petals dropping prematurely. Wilting is another classic sign of overexposure to the sun.
- Dahlias can get too much sun.
- Leaves and flower petals may drop prematurely or turn brown.
- Wilting is a major sign of excessive sun exposure.
- Use these shade cloths to prevent scorching and provide afternoon shade.
If you can’t plant your dahlias in an area where they receive their sun in the morning, consider hanging shade cloths to block some of the afternoon light. Cloths with 30–40% blocking capacity are perfect, as they will prevent wilting and scorching. When the driest part of summer begins, increase deep watering to 3 times per week. This sometimes prevents some of the damage from excessive sun and heat. However, providing adequate shade is still the best option to get the most from your beautiful flowers.
How Much Sun Do Dahlias Require?
When providing sun for your dahlias, follow these rules:
- Dahlias need 6 hours of full sun per-day.
- Up to 8 hours of daily sun is not too much in mild climates.
- Dahlias quickly wilt under excessive sun and heat.
- Morning sun offers the best results.
All day sun is too much for dahlias, so you should provide afternoon shade to your flowers. Their delicate constitution may be damaged by daylong, direct sunlight. Offering morning sun and afternoon shade is the best way to ensure your dahlias flower in the summer and throughout the fall.