Are Coffee Grounds Good For Dahlias? Best Dahlia Fertilizers

Have you ever wondered if your morning cup of Joe could double as flower power? Today, we’re brewing up a blooming good question: Are coffee grounds good for Dahlias?

And while we’re at it, let’s dig into the top-notch fertilizers that’ll make your dahlias the envy of the neighborhood. So grab your trowel and coffee cup and let’s get digging.

Cup of coffee sitting on burlap with coffee beans

Don’t get caught unprepared when dahlia season bursts into bloom! While winter still lingers, February presents the perfect window to plan your cut flower garden.

Acquire the finest Dahlia tubers and seeds from SCC Flower Farm, ensuring you choose a trusted flower farm. Sarah and her family cultivate stunning Dahlias, promising that your garden will become the talk of the neighborhood.

I will share how to nurture your garden soil and get down to the nitty-gritty of Dahlia nutrition. Master the magic of Dahlia fertilizers and their strategic timing – it’s the best way to unlock breathtakingly vibrant blooms. Dust off your gardening gloves and unleash your inner dahlia diva – because you won’t want to miss the show come late spring.

Wendy is holing a basket of Dahlias she just cut from the garden.
Dahlia flower garden

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What are Dahlias?

Do you recall those gorgeous flowers in my garden last summer?  Cafe Au Lait dinner plate dahlias that were 10″ wide? Well, you, too, can grow these beautiful flowers with a few of my tips. 

Little Monroe is holding a giant dinner plate, Dahlia.

Imagine bold fireworks blooming in your garden – that’s a dahlia! These Mexican marvels are bushy perennials, erupting with beautiful blooms in every color imaginable.

Think of blooms the size of dinner plates, delicate pom poms, or fiery pincushions, all lasting from late summer to the sign of the first frost.

There is good news! So don’t be fooled by their drama. They’re easy to grow, thriving in full sun and rewarding you with years of dazzling blooms. So embrace the dahlia flowers – your garden will thank you! 

Are Coffee Grounds Good For Dahlias? 

Coffee grounds are free and typically thrown away but can greatly add to the health of your garden. Did you know you can go to your local Starbucks, which will give you a large bag of spent coffee grounds for free? All you have to do is ask!

Keep this in mind.

  • Coffee grounds are acidic, which can be good for dahlias that prefer slightly acidic soil (pH 6-7). However, adding more could harm your plants if your soil is acidic. I suggest checking the acid levels before using the coffee to ensure healthy dahlia plants. You can do this with a simple soil test.
We are adding coffee grounds to the garden.

Sprinkle a layer of coffee grounds on top of your soil before the growing season and work into your well-drained soil. Used coffee grounds contain about 2% nitrogen, about 1/3% phosphoric acid, and 1% potash, which the Dalias love. This will give your healthy tubers a good start to the growing season. Once the plants are established, you can add 5-8 tablespoons of coffee around the base of the plants weekly. Mix it into the soil without contacting the leaves and stems.

Benefits of Coffee Grounds in the Garden:

  • Nitrogen boost: Coffee grounds contain about 2% nitrogen, a key nutrient for plant growth, especially for foliage growth and a bushier plant.
  • Soil aeration: The coarse texture of the grounds improves soil drainage and aeration, which is beneficial for dahlia tuberous roots.
  • Pest deterrent: The acidity and smell of coffee grounds can deter slugs and snails, spider mites, and other common dahlia pests.

Red Pom Pom Dahlias in the garden
Dahlias growing in the garden.

Drawbacks of Coffee Grounds:

  • Acidification: Too much acid can damage your plants. (check your soil regularly) 
  • Slow nitrogen release: While coffee grounds contain nitrogen, it’s released slowly. This may not be sufficient for heavy-blooming dahlias, especially during peak flowering season, so you will need to add additional fertilizers.
  • Fungus risk:  Coffee grounds can attract and promote fungus growth in humid conditions.

So, are coffee grounds good for Dahlias?

  • Try them if: Your soil is slightly acidic, you have moderate nitrogen needs, and your climate is dry.
  • Skip them if: Your soil is already acidic, or you have humid conditions.
  • I have had great success using coffee grounds in my garden.
Bouquet of dahlias from the garden.

Choosing The Right Fertilizer 

Before fertilizing our dahlias, it is a good idea to understand what is already in your soil and what the nutrient requirements of dahlias are. 

Soil Testing: Before applying any fertilizer, test your soil to determine its nutrient levels and tailor your fertilization accordingly.

Dahlia Nutrient Needs: Dahlias are big bloomers and heavy feeders. While they appreciate a balanced diet, understanding their specific preferences will help you keep them thriving. You will want to prioritize nitrogen during the growth phase and phosphorus during the blooming phase. Potassium benefits overall plant health.

Here’s a breakdown:


  • Nitrogen (N): Crucial for healthy foliage growth, especially in the early stages. However, too much N can lead to stunted blooms and weaker stems. Aim for a moderate N content in your fertilizer, around 5-10% during the growing season.
  • Phosphorus (P): Plays a key role in flower development and strong root systems. Dahlias typically have moderate P needs, so look for fertilizers with a slightly higher P content than N, around 10-15%.
  • Potassium (K): Boosts healthy growth, stress resistance, and disease tolerance. Dahlias benefit from a relatively high K content, about 15-20% in your fertilizer.


  • Boron (B): Aids in pollen formation and seed production. A small amount of boron fertilizer applied during flowering can promote strong blooms.
  • Magnesium (Mg): Essential for chlorophyll production and healthy plants. Deficiencies can show up as yellowing leaves. Most complete fertilizers will contain sufficient magnesium.
Raised bed flower garden

Excellent Type of Fertilizers for Healthy Dahlias

You can choose from several options for fertilizers, organic and non-organic. Here is a list of my go-to fertilizers and how they will best feed your Dahlias.  

Organic Fertilizers 

Coffee: are coffee grounds good for dahlias

  • Coffee grounds are rich in nitrogen and will help to grow a healthier and bushier plant.

Jobe’s Organics Flower & Fruit Granular Fertilizer: 

  • This excellent fertilizer boasts a well-balanced 5-3-3 NPK ratio, perfect for encouraging healthy foliage and flower production. Its slow release makes it gentle on your plants and provides long-lasting nourishment.

Espoma Organic Flower-Tone Fertilizer: 

  • This granular fertilizer features a slightly higher phosphorus content (4-3-2 NPK) to cater to the needs of abundant blooms like dahlias specifically. It’s OMRI-listed for organic gardening and releases nutrients gradually for sustained feeding.

Blood Meal:

  • This dried-up blood delivers a nitrogen supercharge (up to 12%) to fuel lush foliage and early growth. It’s like protein powder for young plants, giving them the energy to reach the sun and boost leaf production. Remember, too much protein can be bad, so use blood meal sparingly and adjust your overall fertilizer plan to avoid burning your blooming beauties. 

Bone Meal: 

  • Rock the blooms with bone meal! This organic fertilizer, made from ground bones, packs a powerful punch of phosphorus (20-30%) for a strong root system and dazzling blooms. Calcium (4-7%) adds muscle, strengthens stems, and boosts overall health. But remember, the slow-release fertilizer means long-term benefits and its slight acidity needs monitoring. Use it wisely for happy dahlias with larger flowers.

Horse Manure: 

  • Manure packs a punch for dahlias!  Nitrogen fuels lush leaves and strong stems, while phosphorus and potassium produce vibrant blooms. Its organic matter boosts drainage and welcomes roots, and teeming microorganisms break down nutrients for long-term dahlia delight. Just handle it carefully to avoid the heat and weeds; your blooms will thank you!


  • This homemade concoction consisting of food scraps and yard waste feast is your dahlia’s dream. Nitrogen, potassium, and microbe friends? All there, creating happy roots, thirsty-quenching soil, and vibrant blooms galore. So recycle, enrich, and watch your dahlias dance with delight!

Non Organic Fertilizer

  • Miracle-Gro Bloom Booster Bloom Food: This water-soluble fertilizer offers a convenient way to deliver a quick nutrient boost to your dahlias. Its 10-52-10 NPK ratio is specifically formulated for blooming plants and promotes abundant blooms with vibrant colors.
  • Jack’s Classic Bloom Booster Fertilizer: This concentrated fertilizer comes in a powder form and boasts a customizable NPK ratio (10-30-20). You can adjust the dilution to match your dahlias’ specific needs, making it ideal for experienced gardeners.
  • FoxFarm Big Bloom Liquid Fertilizer: This organic-based liquid fertilizer provides a balanced blend of nutrients (5-10-10 NPK) and beneficial microbes and humic acids. It helps improve soil quality while nourishing your dahlias for continuous blooming throughout the season.

Tips For Keeping Your Dahlia Beds Healthy 

Planting & Soil:

  • Sunlight: Give them at least 6-8 hours of direct sun for optimal growth and blooming.
  • Create the best soil: Deep, fertile, well-draining soil is key. Amend with compost or manure for the best garden beds possible.
  • Planting Time: Spring after the last frost is ideal. Plant tubers on their side with “eyes” pointing up, about 2-4 inches deep.
  • Spacing: Plant tubers 12-18 inches apart depending on variety size. Taller types may need staking.
Dahlias are just starting to grow in the raised bed garden.

Watering & Feeding:

  • Watering: Deeply water once or twice a week, letting the top inch of soil dry between waterings. Always water in the early morning and at the base of the plant. Do not get the foliage or blooms wet. 
  • Feeding: Use a balanced fertilizer from the list above, and don’t forget the coffee!

General Care:

Deadheading dahlias.
Deadheading dahlias
I pinched back the Dahlia to create a bushier plant.
Pinched back dahlia plant
  • Mulch: Spread a layer of organic mulch around the base of plants to retain moisture, suppress weeds, and regulate soil temperature.
  • Deadheading: Regularly remove spent blooms to encourage more flowers.
  • Pinching: Pinching back new growth can promote bushier growth and larger blooms. Use sharp scissors or pruners to cleanly remove the tip of the main stem, just above a set of leaves. This will encourage the plant to grow two new shoots from the cut point, resulting in a bushier plant with more blooms. Pinch in the morning when the plant is turgid (full of water) for faster healing.
  • Air it out: To avoid fungal issues like powdery mildew, encourage good air circulation by removing the lower leaves off the bottom 10- 12 inches of stem. This opens up the plant and lets air flow freely.
  • Say goodbye to common pests: Slugs and snails find young dahlia leaves irresistible. Keep them at bay by sprinkling diatomaceous earth around the base of your plants or handpicking the culprits after nightfall. You may also want to use Captain Jacks’s Bonide for preventative measures.


Living in an area with freezing temperatures, you must remove the tubers from the ground in the fall and store them for the winter. Removing the tubers from the ground is unnecessary if you live in a zone like I do (10a) where we do not have freezing temperatures. If you want to split the tubers, I advise doing this in the spring.

  • Cure in a cool, dry place: Spread the tubers in a single layer in a well-ventilated area with temperatures between 40-50°F (4-10°C) for 7-10 days. This allows the cuts to heal and reduces the risk of rot.
  • Remove damaged parts: Cut away soft, moldy, or rotten sections with a clean, sharp knife.
  • Label individual tubers: If you have different varieties, write the name on each tuber with a permanent marker.
  • Pack for storage: Choose breathable containers like cardboard boxes, paper bags, or mesh baskets. Fill the bottom with packing material like vermiculite, perlite, or dry peat moss to prevent bruising. Gently nestle the tubers in, making sure they don’t touch. Cover them with more packing material, leaving some headspace for air circulation. You can also opt to wrap them in saran wrap and forego the perlite or peat moss. You will have to experiment to see what works best in your zone.
  • Store in a cool, dark location: Find a spot that’s frost-free, well-ventilated, and maintains temperatures between 35-45°F (2-7°C). Basements, garages, or unheated rooms can work well.
  • Check your tubers periodically: Inspect them every few weeks throughout winter. Remove any rotten or moldy tubers immediately to prevent spoilage from spreading. 
Dahlia tubers
Labeled dahlia tubers

Wrapping It Up

I hope this comprehensive guide has answered your burning question of “Are coffee grounds good for dahlias?” While they can play a supporting role, remember your dahlias crave a balanced diet. Explore the various fertilizer options, from DIY concoctions to store-bought varieties, and find the perfect match for your garden. With consistent feeding and dedicated care, you’ll witness a season of breathtaking dahlia displays that will leave you mesmerized!


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Hello, I’m Wendy – a dedicated “So Cal Gal” with a deep passion for decorating, gardening, cooking, and crafting in California. I find joy in harmonizing beautiful elements to create a space that is both comfortable and inspiring. I will help you create a beautiful home and garden, one project at a time.

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    1. Thank you, Michele; I hope you have gorgeous dahlias this year.

  1. Great tips, Wendy. I have never grown Dahlias before. Many other plants and flowers but not Dahlias. Your Dahlias were gorgeous.

    1. Hi Tammy, I bet you could easily grow some yourself. Dahlias are my favorite flowers and I have had good luck with them in raised beds.

  2. Wendy, your dahlias are gorgeous! We cannot grow them here but I’m hoping to try growing them up at our cabin. Thanks for all the great tips.

    1. Thank you, Mary; I hope you succeed at the cabin. They are such beautiful flowers.

  3. These are gorgeous! I cannot believe the size! So beautiful!!

    1. Thank you so much, Susan. They get to be 12″ around, crazy, I know. I hope they are as good this year.

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