The 5 Best Fertilizers for Dahlias

Only the best fertilizers will deliver the best results for your dahlias. The problem is that there is a drastic difference between the quality of fertilizers in local gardening shops. It’s difficult to differentiate between good products and bad products because of all the media hype. Don’t make the mistake of choosing an bad fertilizer and finding out too late. 

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Do you want your dahlias to grow up strong and healthy? If so, you should spend the time to find the best fertilizer for your dahlias. Having a fertilizer that delivers the correct nutrients in a way that is able to be taken up by the your dahlias’s root zone is of utmost importance. I will help you learn what you need to know about choosing the best for your dahlias and also finding a fertilizer that uses quality ingredients to deliver the proper nutrients and an affordable price.

5 Best Fertilizers for Dahlias Comparison Table

Here I have a table of the best fertilizers for dahlias that is compiled in an easy-to-read format and ranked from the least expensive to the most expensive (from the time I wrote these reviews). Keep in mind that price is not everything. On the one hand, just because a product is more expensive does not mean it is better. On the other hand, oftentimes more expensive products are more expensive because they use higher quality ingredients. For those of you on cellphones or smaller screens, you may need to click the green symbol in the left corner of each image in order to access more details.

5 Best Fertilizers for Dahlias

To raise healthy dahlias, you’ll need the best fertilizer possible. When you are looking for the proper fertilizer you want to look for the right N-P-K ratio, high quality ingredients, and oftentimes a fertilizer with portions of slow release nitrogen. Keep reading the reviews below to learn about the fertilizers that we recommend.

  • N-P-K Ratio: 8-9-12

  • Fertilizer type: Spikes

  • Amount: 18 Spikes

Jobe’s Potted Plants Fertilizer Spikes are one of the easiest ways to ensure that potted plants such as dahlias receive the correct amount of fertilizer. These spikes are pre-measured and are easy to insert near the plant’s roots. The time release formula is specifically crafted to nourish flowering plants, and because it is designed to release slowly, the spikes will feed plants for up to two months. In addition, because it comes in a spike that’s inserted directly into the soil, this fertilizer has no mess and will not create harmful or wasteful runoff during watering. Plants treated with these fertilizer spikes will grow faster and larger. They will also have fuller foliage and larger, more colorful blooms.

  • N-P-K Ratio: 4-10-7

  • Fertilizer type: Granules

  • Amount: 4 lbs

For an organic fertilizer specifically designed for flowers, Dr. Earth Organic Bud & Bloom Fertilizer is an excellent choice. This fertilizer is made of natural ingredients that include feather meal, soft rock phosphate, fish bone meal, alfalfa meal, and potassium sulfate. These ingredients are specifically blended to create the optimum food for bulbs, rhizomes, and tubers. The formula also contains pro-biotics, mycorrhizae, and microbes. These help to grow healthier, stronger plants. The ingredients also enhance the soil, helping to establish stronger root structures and assisting in drought resistance. In addition, the slow release formula will nourish plants for several months. Gardeners will find that dahlias treated with this fertilizer produce larger, more abundant blooms.

  • N-P-K Ratio: 3-5-5

  • Fertilizer type: Granules

  • Amount: 16 lbs

Jobe’s Organic Annual & Perennials Plant Food is a perfectly balanced fertilizer that is crafted to help annuals such as dahlias become healthier and hardier. The plant food is made entirely from natural materials, so it is not only excellent for plants but is also safe for children and pets. In addition, it is gentle enough that it won’t burn a plant’s leaves. The formula contains Jobe’s special biozome, which helps to increase the nutrients and condition of soil. This in turn leads to stronger root systems. The fertilizer can be mixed directly into the soil and will feed plants for between one to two months. When used on dahlias, gardeners will notice that their plants are healthier overall, with greener leaves and larger, more colorful flowers.

  • N-P-K Ratio: 3-4-5

  • Fertilizer type: Granules

  • Amount: 18 lbs

Epsoma Flower-Tone is designed to promote large, abundant, colorful flowers. The fertilizer mix is crafted to specifically enhance blooms so foliage never outshines a dahlia’s flowers. The formula contains a balanced ratio of phosphorus and potassium but is low in nitrogen, which makes it perfect for annuals. In addition, the fertilizer contains microbes that will enhance the quality of the soil. This ensures that nutrients are delivered directly to the plant’s roots and also helps make plants more drought resistant. Epsoma’s slow release formula also ensures that plants will be fed continuously for an entire season.

  • N-P-K Ratio: Not listed

  • Fertilizer type: Spikes

  • Amount: 100 Spikes

Earthpods Premium Bloom Flowering Plant Fertilizer Spikes are some of the easiest fertilizers to apply to plants. Gardeners can simply insert an EarthPod into the soil near the center of the plant. After watering, the Earthpod breaks down and the slow release formula goes to work, delivering a steady stream of nutrients directly to the plant’s roots. This fertilizer formula contains soil microbes, nutrients that are specifically balanced for flowering plants such as dahlias, humic and fulvic acid, natural growth hormones, and small amounts of minerals. Dahlias treated with this mix are often healthier from the root system up, with more vibrant, colorful flowers.

Tips for Dahlia Care

There are no flowers that give gardeners more of a beautiful reward than dahlias. Once you start growing them, it’ll be like you can’t stop because of how magnificent they are. If you’ve never grown a dahlia, it’s time that you tried raising some. Raising healthy dahlias that bloom many flowers is not difficult and with the right tools I’m sure you that your garden will be filled with color and beauty.

Warm Your Dahlia Tubers

Most times, you will buy and plant dahlia tubers. Even though they look like bulbs, the roots of the dahlia are called tubers. They sometimes look like a bunch of radishes or carrots and the stems of the dahlia will grow directly from these tubers. Dahlia prefer to grow in warmer temperatures so I recommend that you grow them indoors until it has properly warmed up outside. You’ll want to wait until its about 60 degrees Fahrenheit before transplanting them to the outdoors. Make sure that when you are laying your tubers into the ground that you give them enough room to grow. Depending on the variety of the dahlia, it may need to be spaced anywhere from 12 inches to 3 feet apart.

Keep Away Weeds

Weeds fight for nutrients that dahlia require to grow properly. Make sure to remove any weeds and try to use organic mulch around the plant to prevent weeds. Hand weeding is the only type of weed control that should ever be used. Weed killers will undoubtedly damage or kill your dahlia.

Proper Fertilization

The best fertilizers are not too high in their nitrogen content and have greater amounts of phosphorous and potassium. N-P-K ratios of about 1-2-2 (such as 10-20-20 or 5-10-10). One of the biggest mistakes that I see made are feeding dahlias fertilizers with high nitrogen contents. Nitrogen tends to promote huge plants with weak stems and small or no blooms. Fertilizers with no nitrogen component can even be used in the late blooming season to further increase bloom. The general rule of thumb is that you will want to fertilize monthly with water soluble fertilizers or twice during the grow season with granules scattered around the root zone of the dahlia. That being said, make sure to follow the instructions on the product label of the fertilizer that you buy.

Deep Watering

As you water your dahlias, try to avoid getting water onto the foliage as this can lead to diseases. One way to do this is to use soaker hoses which direct water into the soil around your plants rather than sprinkling it up into the air. Also, avoid overwatering as this can lead to rotting tubers. Less frequent, but deep watering is preferred. Water early in the morning so that the sun can help dry out the soil a little throughout the day.

Pruning When It’s Young

You will want to prune or pinch the center shoot of your dahlia plant above the third set of leaves. This will help shape the dahlia so it is slightly shorter, bushier, and fuller looking. By doing this, you will also enforce good structure and increase budding.  

Wrapping it up

I am sure that you will have great success in raising healthy dahlias using one of these fertilizers. Make sure to be careful to follow the product instructions in regards to how much fertilizer to use. Remember not to use too much or too little!

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Happy Planting!

About the author: Carley Miller is a horticultural expert at TheGreenPinky. She previously owned a landscaping business for 25 years and worked at a local garden center for 10 years.

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