Potted geraniums are summer showstoppers—but only if they’re properly fed. The right fertilizer routine can mean the difference between leggy, lackluster plants and full, blooming beauties.
These 16 easy tips will help you keep your geraniums thriving, and the 2 bonus tricks at the end? Gardeners swear by them for next-level results.
1. Choose a Balanced Fertilizer
Balanced fertilizers with equal parts nitrogen, phosphorus, and potassium (like 10-10-10) provide complete nutrition for potted geraniums. The numbers represent the percentage of each nutrient in the mix.
Nitrogen supports leafy growth, phosphorus promotes flowering, and potassium strengthens overall plant health. During active growing seasons, this balanced approach ensures your geraniums develop strong stems while maintaining impressive flower production.
2. Dilute Liquid Fertilizers
Always dilute liquid fertilizers to half the recommended strength on the package. Geraniums can be sensitive to fertilizer burn, especially in containers where nutrients don’t disperse as widely as in garden soil.
The concentrated solution straight from the bottle is too powerful and risks damaging your plant’s roots. Mixing with water creates a gentler feeding experience that geraniums appreciate, allowing nutrients to be absorbed gradually without shocking the system.
3. Apply Fertilizer When Soil Is Moist
Never feed your geraniums when the soil is completely dry. Dry roots absorb fertilizer too quickly, which can burn delicate root tissues and stress the plant.
Water your pots thoroughly a day before fertilizing to ensure the soil is evenly moist. This preparation step allows the roots to take up nutrients gradually and safely. Think of it as giving your plant a drink before serving its meal – proper hydration helps with nutrient digestion!
4. Bloom-Boosting Phosphorus
For spectacular flowers, switch to a high-phosphorus fertilizer when buds start forming. Look for formulations where the middle number is highest (like 5-10-5) to encourage abundant blooms.
Phosphorus directly supports the flowering process, helping geraniums produce bigger, brighter, and more numerous blooms. Many gardeners keep two fertilizer types on hand – one balanced formula for general growth and a high-phosphorus option to maximize flowering potential during the showtime season.
5. Slow-Release Granules Save Time
Sprinkle slow-release fertilizer granules on the soil surface every 3-4 months for hassle-free feeding. These coated pellets gradually dissolve with each watering, providing a steady nutrient supply without the need for weekly applications.
Perfect for busy gardeners, this method ensures your geraniums receive consistent nutrition without the risk of feast-or-famine cycles. The granules continue working even when you forget, making them ideal for vacation periods or hectic schedules.
6. Feed During Active Growth
Spring and summer are prime feeding seasons for geraniums. During these warm months, your plants are actively growing and flowering, demanding more nutrients to fuel their development.
Establish a regular feeding schedule every 2-3 weeks during this period. As temperatures cool in fall, reduce fertilizer applications to once monthly. Winter feeding should be minimal or eliminated entirely, as geraniums naturally slow their growth and enter a semi-dormant state.
7. Compost Tea Magic
Homemade compost tea provides gentle, organic nutrition that geraniums love. Simply steep a cup of finished compost in a gallon of water overnight, then strain and use the liquid to water your plants.
This natural brew contains beneficial microorganisms that improve soil health while delivering nutrients. Unlike chemical fertilizers, compost tea enriches the growing medium with complex organic matter that feeds plants gradually. Apply this miracle drink every two weeks for vibrant, healthy geraniums.
8. Banana Peel Boost
Save those banana peels! Cut them into small pieces and bury them just below the soil surface around your geraniums. As they decompose, banana peels release potassium, calcium, and phosphorus – key nutrients for strong stems and prolific flowering.
Unlike commercial fertilizers, this kitchen scrap solution costs nothing and reduces waste. The decomposition happens slowly, providing a gentle, extended-release feeding effect. Your geraniums will respond with brighter blooms and more vigorous growth.
9. Epsom Salt Solution
Monthly treatments with Epsom salt solution can transform yellowing geraniums. Dissolve one tablespoon of Epsom salt in a gallon of water and use it to water your plants.
The magnesium sulfate in Epsom salt helps plants produce chlorophyll, the compound responsible for green leaf color and photosynthesis. Many container soils become magnesium-deficient over time, leading to yellowing leaves despite regular fertilizing. This simple supplement corrects the imbalance, restoring vibrant foliage.
10. Coffee Grounds Revival
Used coffee grounds work wonders as a slow-release nitrogen source for geraniums. Sprinkle a thin layer (about ¼ inch) over the soil surface monthly, gently working it into the top layer without disturbing roots.
Coffee grounds gradually acidify alkaline soils, creating ideal pH conditions for nutrient absorption. They also improve soil texture in containers, preventing compaction. As an added bonus, many gardeners report that coffee grounds deter pests like aphids and slugs that might otherwise target your precious geraniums.
11. Eggshell Calcium Supplement
Crushed eggshells provide essential calcium that prevents blossom end rot and strengthens cell walls in geranium stems and leaves. Rinse, dry, and crush shells into a fine powder before sprinkling around plants.
The calcium releases slowly as shells decompose, creating a long-lasting supplement. Strong cell walls mean more disease resistance and better water retention in plant tissues. For maximum benefit, combine your eggshell application with a slightly acidic fertilizer that helps calcium absorption.
12. Avoid Over-Fertilizing
More isn’t always better when feeding geraniums. Excessive fertilizer causes salt buildup in containers, burning roots and creating lanky plants with few flowers. Watch for warning signs like white crust on soil or pot rims.
If you suspect over-fertilization, flush the pot thoroughly with plain water until it runs freely from drainage holes. Then wait 2-3 weeks before resuming fertilization at half strength. Remember that under-fertilized geraniums recover more easily than over-fertilized ones – when in doubt, go light!
13. Prune Before Feeding
Strategic pruning before fertilizing creates spectacular results. Remove spent blooms, yellowing leaves, and leggy stems just before applying fertilizer to direct energy toward new growth.
Pruning stimulates hormonal changes that make plants more receptive to nutrients. When timed with fertilization, this one-two punch triggers an explosion of fresh growth and flower production. Aim to remove no more than 25% of the plant at once to prevent shock.
14. Water-Soluble Fertilizers For Quick Results
Water-soluble fertilizers deliver fast-acting nutrients directly to roots, perfect for rescuing struggling geraniums. Unlike granular options, these completely dissolve in water for immediate availability to plants.
Results often appear within days – yellowing leaves green up, and new growth emerges quickly. For severely nutrient-deficient plants, apply weekly at half-strength for three weeks, then return to regular feeding schedules. Keep the solution off leaves to prevent spotting or burning in strong sunlight.
15. Kelp Meal For Micronutrients
Kelp meal provides trace minerals often missing from standard fertilizers. These micronutrients – including iron, manganese, and zinc – play crucial roles in plant enzyme systems and chlorophyll production.
Sprinkle a tablespoon of kelp meal over the soil surface monthly, working it in gently. Alternatively, brew kelp tea by steeping kelp meal in water overnight. Geraniums receiving these sea-derived nutrients develop exceptional stress tolerance, resisting both drought and cold better than unfed plants.
16. Adjust pH For Nutrient Availability
Geraniums absorb nutrients best when soil pH falls between 6.0 and 6.5. Even perfect fertilizer won’t help if pH is wrong! Test potting mix with an inexpensive soil pH kit from garden centers.
To lower pH (make soil more acidic), water with a dilute vinegar solution (1 tablespoon per gallon). To raise pH (make soil more alkaline), sprinkle crushed limestone over the soil surface. Proper pH management ensures your fertilizer investment actually reaches your plants instead of becoming chemically locked in the soil.
17. BONUS: Worm Casting Tea
Garden experts swear by worm casting tea as the ultimate geranium energizer. This potent brew combines the benefits of compost tea with exceptionally high microbial activity from worm digestive processes.
Fill a cloth bag with worm castings and steep it in water like a giant tea bag for 24-48 hours. The resulting liquid contains humic acids that help plants absorb nutrients more efficiently. Monthly applications of this brown gold create visibly healthier geraniums with remarkable disease resistance.
18. BONUS: Chamomile Tea Spray
Professional greenhouse growers use chamomile tea as a secret weapon for geranium health. Brew strong chamomile tea (using 4-5 tea bags per quart), cool completely, then spray directly on geranium foliage weekly.
The natural compounds in chamomile act as both gentle fertilizer and disease preventative. Antifungal properties help ward off powdery mildew and botrytis, common geranium problems. Meanwhile, trace minerals in the tea strengthen cell walls. This dual-action treatment keeps plants looking pristine while boosting growth.