Beautiful, reliable geraniums deserve more than just occasional feeding if you want those signature clusters of red, pink, or white flowers all season long. The right fertilizing approach can transform ordinary plants into showstoppers that keep blooming from spring until frost.
I used to think feeding them once or twice in spring was enough, but after learning a few small tweaks, the difference in blooms was huge. My containers went from sporadic flowering to non-stop color machines!
These pro tips represent exactly what works for maximum flowering potential—no fluff, just practical advice. Whether you’re growing geraniums in pots or garden beds, these seventeen fertilizing strategies will help you achieve the abundant blooms these plants are famous for.
1. Know Your Geranium Type First
Different varieties have slightly different nutritional needs. Zonal geraniums (the common round-leaf type) are moderate feeders, while ivy geraniums climbing down your hanging baskets need slightly less fertilizer. Regal or Martha Washington types prefer cooler temperatures and lighter feeding.
I discovered this after accidentally over-fertilizing my Martha Washingtons and getting lots of leaves but few flowers. Take a quick photo of your plant and confirm its type before setting up your feeding schedule.
This small step prevents wasted effort and ensures you’re not giving too much or too little of the nutrients your specific plants crave.
2. Balance Is Everything – The 10-10-10 Rule
A balanced fertilizer with equal parts nitrogen, phosphorus, and potassium (10-10-10) works wonderfully for most geraniums during their active growing phase. This trio of nutrients supports overall plant health while encouraging flower production.
Last summer, my neighbor’s geraniums outperformed mine until I switched to this balanced approach. The nitrogen supports leafy growth, phosphorus promotes blooming, and potassium strengthens stems and roots.
For container geraniums especially, this balanced formula prevents the common problem of all-leaf, no-flower plants that many gardeners struggle with each season.
3. Switch To Bloom-Boosting Formula Mid-Season
Once your geraniums are established with healthy foliage, transition to a phosphorus-rich fertilizer (like 5-10-5) to encourage more flowers. The middle number being higher tells you it’s formulated specifically to promote blooming rather than leaf growth.
My patio containers struggled until July when I made this simple switch. The plants responded within two weeks with twice as many flower buds!
This mid-season change mimics what professional growers do – they build plant structure first, then trigger the flowering phase with different nutritional ratios. Time this transition around early summer for best results.
4. Liquid Fertilizer For Fast Results
When geraniums need a quick nutrient boost, nothing beats liquid fertilizer. It delivers nutrients directly to the roots in a form plants can immediately absorb, often showing visible improvement within days.
During a particularly hot spell last August, my geraniums looked stressed and stopped flowering. A single application of liquid seaweed fertilizer revived them within a week.
For potted geraniums especially, liquids are ideal since nutrients in containers deplete faster than in garden soil. Just be careful not to splash the leaves, as wet foliage can lead to fungal issues in humid weather.
5. Slow-Release Granules For Low-Maintenance Care
For busy gardeners, slow-release fertilizer granules are a game-changer. These tiny time-release capsules feed geraniums consistently for 2-3 months, eliminating the need for weekly fertilizing sessions.
After forgetting to feed my porch geraniums during a hectic month, I switched to slow-release and never looked back. Simply sprinkle the recommended amount around the base of plants in spring, lightly work into the soil, and water thoroughly.
The steady nutrient release prevents the feast-or-famine cycle that can stress plants. Just remember to reapply mid-summer for continuous blooming through fall.
6. Morning Fertilizing Maximizes Absorption
The timing of fertilizer application matters more than most gardeners realize. Early morning is ideal – plants absorb nutrients most efficiently during their active growing hours when stomata are fully open.
My side-by-side test with identical geraniums showed 30% more blooms on morning-fed plants compared to evening-fed ones. The morning group utilized nutrients during peak photosynthesis hours rather than having them sit unused overnight.
This small scheduling tweak costs nothing yet significantly improves results. Aim for application between 6-9am for maximum benefit, especially during summer’s active growing period.
7. Always Water Before Fertilizing
Never apply fertilizer to dry soil or stressed plants. Always water thoroughly first, then wait 30 minutes before feeding. This prevents fertilizer burn and ensures nutrients distribute evenly throughout the root zone.
I learned this lesson the hard way after scorching several prized geraniums with fertilizer applied to parched soil. The moisture barrier creates a buffer that protects sensitive root tissues from concentrated nutrients.
This pre-watering step is especially crucial during hot weather when plants are already under stress. Think of it as preparing the plant’s digestive system before serving a nutrient-rich meal.
8. Half-Strength Is Often Enough
Commercial fertilizers are typically formulated for maximum results across many plant types, but geraniums often thrive with half the recommended dosage. This gentler approach prevents leggy growth while still supporting abundant blooms.
My container geraniums produced more compact, flower-filled plants when I cut the recommended dose by 50%. The plants directed energy toward flowers instead of excessive foliage.
Start with half-strength applications every two weeks rather than full-strength monthly. You’ll use the same amount of product overall while maintaining steadier nutrient levels and avoiding the feast-or-famine cycle that can stress plants.
9. Organic Compost Tea For Natural Feeding
For organic gardeners, homemade compost tea provides complete nutrition without harsh chemicals. This gentle brew contains beneficial microorganisms that improve soil health while feeding your geraniums.
After switching to compost tea for my heirloom geraniums, I noticed improved disease resistance alongside consistent flowering. Simply steep finished compost in water for 24-48 hours, strain, and apply the resulting amber liquid at the base of plants.
Unlike synthetic fertilizers, compost tea can’t burn plants even in hot weather. The living biology in the tea also helps break down existing soil nutrients into more plant-available forms.
10. Watch For The Telling Leaf Color
Your geranium leaves reveal exactly what nutrients they need. Pale yellow-green upper leaves typically indicate nitrogen deficiency, while purple tinges on otherwise green leaves often signal phosphorus shortage.
My balcony geraniums developed yellowish leaves last June, and a nitrogen-rich feeding resolved the issue within weeks. Meanwhile, older leaves turning yellow while veins stay green usually points to iron or magnesium deficiency.
Take close-up photos of concerning leaves to compare with reference guides or bring a sample to your local garden center. This detective work ensures you’re addressing the specific deficiency rather than guessing.
11. Coffee Grounds For Acid-Loving Varieties
Used coffee grounds make an excellent supplemental fertilizer for geraniums that prefer slightly acidic soil, like certain regal varieties. The grounds add organic matter while gently lowering soil pH.
My mother’s prize-winning pink geraniums received a monthly sprinkle of dried coffee grounds, which she swore made the colors more intense. Allow grounds to dry completely before use to prevent mold, then work a thin layer into the soil surface.
This recycled kitchen waste also adds trace minerals and slowly releases nitrogen as it decomposes. Just don’t overdo it—a quarter-inch layer once monthly is plenty.
12. Foliar Feeding For Quick Recovery
In emergencies when geraniums look severely nutrient-deprived, foliar feeding can provide the fastest turnaround. This method involves spraying diluted liquid fertilizer directly onto leaves where nutrients absorb through the stomata.
After a lengthy vacation, I returned to sad-looking geraniums that perked up remarkably within 48 hours of foliar feeding. Use only fertilizers specifically labeled for foliar application at quarter-strength, and apply in early morning when stomata are open.
This technique supplements rather than replaces regular feeding. It’s particularly useful for correcting specific deficiencies or reviving stressed plants when you can’t wait for root uptake.
13. Stop Fertilizing Before Fall Dormancy
Contrary to common practice, geraniums need a rest period. Taper off fertilizing about 6-8 weeks before your first expected frost date to help plants transition to dormancy naturally.
When I continued feeding into September, my overwintered geraniums struggled with leggy, weak growth. Late-season fertilizing forces new growth that won’t have time to mature before cold weather, making plants vulnerable to frost damage.
This scheduled stop also triggers the plant to focus on hardening off existing growth rather than producing tender new shoots. For those bringing geraniums indoors for winter, this timing prepares them for their semi-dormant indoor period.
14. Epsom Salts For Magnesium Boost
Occasionally, geraniums develop yellowing between leaf veins while the veins remain green – a classic sign of magnesium deficiency. A simple solution lies in your bathroom cabinet: Epsom salts.
The transformation in my container geraniums after one Epsom salt treatment was remarkable – new leaves emerged deep green within weeks. Dissolve one tablespoon in a gallon of water and apply monthly as a supplement to regular feeding.
This treatment works because Epsom salts are magnesium sulfate, delivering the exact micronutrient geraniums sometimes lack, especially in containers or sandy soil. The magnesium plays a crucial role in chlorophyll production and overall plant vigor.
15. Banana Peel Tea For Potassium Power
Before tossing banana peels into the compost, consider making a potassium-rich tea for your geraniums. This homemade fertilizer provides the potassium that strengthens stems and improves flower production.
My grandmother’s spectacular window box geraniums benefited from this old-fashioned remedy for decades. Simply soak chopped banana peels in water for 2-3 days, strain, and use the resulting brew to water plants.
The potassium helps plants develop stronger cell walls, improving drought tolerance and disease resistance. This free fertilizer supplement works particularly well during the heavy blooming period when plants need extra potassium for flower formation.
16. Adjust PH For Maximum Nutrient Availability
Even perfect fertilizing won’t help if your soil pH is wrong. Geraniums absorb nutrients most efficiently when soil pH falls between 6.0-6.5, slightly acidic but not extremely so.
Testing my garden beds revealed alkaline soil at 7.8, explaining why my geraniums struggled despite regular feeding. After amending with sulfur to lower the pH, the plants finally accessed the nutrients that had been locked in the soil all along.
Invest in an inexpensive soil pH test kit and check both container and garden soil. For high pH (alkaline), add sulfur or peat moss; for low pH (too acidic), add garden lime according to package directions.
17. Rotate Fertilizer Types To Prevent Imbalances
Using the same fertilizer exclusively can create nutrient imbalances over time. Smart gardeners rotate between synthetic and organic options to provide a complete spectrum of macro and micronutrients.
After three years of using only synthetic fertilizer, my geraniums developed subtle micronutrient deficiencies. Alternating between compost, fish emulsion, and conventional fertilizer resolved the issue by providing different nutrient profiles.
Create a simple rotation schedule: use a balanced synthetic fertilizer for two applications, then an organic option for the next two. This prevents buildup of certain elements while addressing potential gaps in your primary fertilizer’s formulation.
18. Customize Feeding By Container Size
Smaller pots need more frequent fertilizing than larger containers or garden beds. The limited soil volume in small containers means nutrients deplete much faster, often requiring weekly feeding during peak growing season.
My window box geraniums in 6-inch pots needed fertilizer twice as often as identical varieties in 12-inch containers. The soil volume directly impacts how quickly nutrients get used up or washed away through drainage holes.
As a general rule, containers under 8 inches need weekly feeding at quarter strength, 8-12 inch pots need biweekly feeding at half strength, and larger containers can follow standard monthly schedules. This scaled approach prevents both under and over-fertilizing.