Dahlia plants have their fair share of problems, from sprouting, and pests, to even buds that do not open. It tends to be fairly rare that no flower buds will actually open, but it is relatively common to have a couple of buds that simply refuse to open. The good news is that as long as some buds open, the Dahlias will flower, and all you have to do is to remove the buds that didn’t open and the plant will create more buds which hopefully will open.
Insufficient water can prevent dahlia buds to open. To ensure proper hydration, moisten the soil around your dahlia plant to a depth of 1 inch (2.5 cm) if it appears dry. Adding mulch around the plant can help retain moisture and prevent it from drying out between waterings. Another common mistake that hinders dahlia buds from opening is over-fertilization.
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Dahlia buds and spent flowers look relatively similar, so you might think that the buds have not opened when in fact they have already flowered. Dahlia buds are round in shape, and spent flowers are cone-shaped. Dahlia buds will open at different times, some will open in 3-4 days while others could take even 2 weeks to open. There are a couple of factors that determine how fast the Dahlia buds open, but for the most part, they tend to need a little bit more water.
Unusual weather conditions like extremely hot days and cold nights can also impact the flower buds, some of these will eventually open, but some will simply die off. In case your Dahlias simply refuse to flower then check out my recent article Dahlias Not Flowering ( Top 7 Reasons ).
Dahlia Buds Not Opening
When dahlia buds fail to open, it can be disheartening. One possible reason is insufficient sunlight. Dahlias require at least 6 to 8 hours of direct sunlight to bloom properly. If they are planted in a shady or partially shaded area, the lack of sunlight can prevent the buds from opening fully. Another factor could be environmental stress. Extreme heat, cold temperatures, or fluctuations in weather conditions can cause the buds to remain closed. Additionally, overwatering or improper watering practices can lead to bud rot, causing the buds to wither and not open. It’s also important to consider the age of the plant. Young dahlia plants may take longer to develop and open their buds compared to mature ones.
Not Enough Water
Dahlia plants tend to be thirsty especially once they start growing flower buds, usually, these plants will need a little bit more water at this time. Usually, Dahlias will flower in July or August, and at this point, the weather tends to be the hottest. If your area didn’t get a lot of rain during the Dahlia’s blooming period then you need to water them. Dahlia plants that are wilting, but have flower buds will delay the opening of the buds until they get enough water.
Once the plants get more water, they will bounce back, and eventually, the flower buds will open, but their flowering will be delayed by a couple of days or weeks. If you have relatively hot days in your area, then make sure to water your Dahlias in the evening, this way they can absorb the water rather than the water simply evaporating due to the heat. There are a couple of chores that you can do so your Dahlia tubers sprout faster, for more info check out my recent article What To Do With Dahlia Tubers In Spring? ( Top 6 Chores ).
Rotting Dahlia Buds Will Not Open
It tends to be somewhat rare that Dahlia buds simply rot away but it could happen. Rotten Dahlia buds will not be able to open, and sooner or later they will fall off. The clear sign that the buds are rotten is brown Dahlia buds, or slowly turning brown. If your Dahlia plant has a couple of rotten buds then simply remove these. Usually, the buds rot due to fungal or bacterial issues, which are caused by poor air circulation around the plant and way too much moisture, but most likely some water got into the flower bud and is rotting it from the inside out.
This can easily happen if your area gets a lot of rain in a short period of time or if you water your Dahlias improperly. If the rotting flower buds are caused by the local weather, then cut the rotten buds down, and try to increase the air circulation around the plants. On the other hand, bud rot can also occur if you water your Dahlia’s from above, so make sure to water them from below. If you want to know if your Dahlia tubers are dead or not, then check out my recent article How To Tell If Dahlia Tubers Are Dead? ( Top 7 Signs ).
Western Flower Thrips Causing Dahlia Buds Not To Open
Western flower thrips can cause Dahlia buds not to open, or to open up partially. These thrips will lay their eggs on the Dahlia flower buds, and their larvae will live off the Dahlia petals which are still forming in the buds. If the thrips infestation is serious then they will eat most of the petals before the buds actually have a chance to open. On the other hand, if the infestation is less severe most of the petals should be intact and the buds should open, although in most cases the flower petals will be somewhat discolored and rather small.
Sadly there is no easy fix for this issue because from the outside these infested buds do look healthy and you will only notice that there is a problem if they have not opened for a relatively long time.
Mites Causing Dahlia Buds Not To Open
If you have been growing Dahlias for a couple of years already then you probably know how problematic mites can be. Mites will feed off the sap of the Dahlia plants, and a serious infestation can suck an entire plant dry. Mites tend to love Dahlia flower buds, usually, the concentration of nutrients is relatively high in the buds, which makes them an excellent place for mites to feed and reproduce.
These mites are soo small that you can only see them under a microscope, but you can easily see evidence that they are on the plant. Usually distorted and discolored Dahlia flower buds are a clear sign that mites are feeding on the buds. These buds will fall off, but in case they actually open the flowers will be discolored and have an odd shape to them. These mites thrive in wet and cool weather, so make sure to only plant your Dahlias outside when the weather gets hotter.
Water Getting Into The Buds
There can be several reasons why water could get into the flower buds, from damage by insects, to simply a random raindrop falling in the wrong place. Usually, this tends to happen when the flower buds are slowly starting to open. In certain cases, this trapped water can start to rot the entire flower bud away. Thirsty birds and insects can damage the flower buds in order to access the water trapped inside the bud, thus damaging the flower bud which might not be able to open. In this case, make sure to shake the Dahlia plants after a heavy rain, this should get most of the water off the plant and hopefully from inside the flower bud.
Key Takeaways
- The main reason why Dahlia buds do not open is because they do not get enough water. Dahlia plants need more water when they flower and they will delay opening their flower buds if they are thirsty or wilting. In addition to this, thrips and mites can damage the flower buds to a point where they can no longer open. If water enters the flower buds it can damage or simply rot away the buds and they will not open.
- Make sure to remove the rotting flower buds, this way the plant can grow new ones.
- Water the Dahlias from below, as excess moisture on the leaves and buds could attract mites and thrips.