One of my favourite moments in Spring is when Geraniums (also known as Pelargoniums or Storksbills) come into flower, and I’ve personally (through some trial and error!) found first-hand all the tips and tricks to keep them flowering all the way to Fall!
I used to grow geraniums as part of my job at a garden centre, and I’ve gotten pretty adept at diagnosing why geraniums aren’t flowering and what can be done to ensure your flowers! In this article, I’ll share with you various tests I’ve done to improve geranium flowering and distil all the tips into an actionable process.
Short on time? Let’s get to the point!
Geraniums do not flower because of damp soil, too much shade, cold temperatures, and high nitrogen fertilizer. To bloom in the summer, they require well-draining soil, potassium fertilizer, full sun, and nightly temperatures consistently above 55°F (12°C).
Keep reading to learn why your geraniums are not flowering and how to implement the best practices for geraniums to bloom to their full potential…
Over Watering or Slow Draining Soils
From my research, I discovered that of approximately 250 species, 80% of all Geraniums (Pelargoniums) are native to South Africa, where they flower almost all year in soil that tends to dry out somewhat due to warm weather and in between spells of infrequent rainfall.
So this gives us some clues about how our geraniums would be treated if they were to flower!
In my opinion, the most important factor in getting your geranium to flower is replicating the watering conditions and soil moisture of its natural habitat.
Two of the most common reasons for germanium not flowering that I’ve identified are because of:
- Watering too frequently so that the soil remains moist or damp.
- Slow-draining soils such as clay or because of boggy low-lying areas.
When I worked in a garden centre and maintained plants before the sale, I noticed the geraniums were not flowering to my satisfaction despite my best efforts! I had to speak with a colleague who was heavy-handed with the watering can while I was off shift!
Damp, boggy soils can stress the geranium and cause fungal diseases such as root rot, which prevents effective root respiration and limits the germanium’s potential for flowering.
So, if your geraniums are not flowering, my advice is to scale back your watering schedule so that the soil has a chance to dry out somewhat between bouts of watering.
How do we do this? I’ve experimented with watering frequency, and typically, I’ve found it best to water geraniums in pots and containers once a week during the Summer if there has been little rainfall and only water geraniums planted in garden borders when there is a drought.
I have a big caveat to this advice: There is no universal watering advice that will be relevant for all who are reading this. The important thing is to adjust the frequency of watering (so that the soil has a chance to dry out) to suit your specific climate and weather conditions.
I got an email from a reader called Patricia regarding water gerniums which asked “What is the best method for telling how often, I should water my geraniums so that the flower? I tried using a water gauge but I found it unrelaible”.
Well, my favourite tried-and-tested method to determine whether your geraniums require watering is to test the soil to a finger’s depth. If the soil is damp, skip watering for a few days, but if the soil is beginning to feel dry, give the geranium a good soak.
I concur with Patricia that water gauges are very hit-and-miss, which is why I prefer the finger-in-the-soil method!
But what if your soil is naturally boggy or slow-draining because of clay or compacted soil? My solution is to plant your geraniums in pots, containers, or hanging baskets to replicate the preferred dryer soil conditions, which increases the geranium’s chance of flowering.
I love using geraniums for hanging baskets as they can tolerate dry, well-draining conditions better than most flowering plants!
So, if your soil is consistently damp, then I would transplant any geraniums as a matter of priority to an area of full sun and well-draining soil to increase the prospect of a good flower display.
I also think its important to remember that we need to always water geraniums with a good soak, as this encourages the roots to grow and establish in the soil and increases the plant’s resistance to drought.
Why Are My Potted Geraniums Not Flowering?
So, I thought I’d cover some of the problems I encounter that are specific to potted geraniums.
Geraniums thrive and flower exuberantly in pots due to the favourable drainage conditions. However, I must caution that your pot or container must have drainage holes in the base for excess water to escape.
This is a classic mistake I’ve seen many fellow gardeners make!
In pots and containers without good drainage, the soil becomes boggy, and the plant either dies of root rot or becomes water-stressed and does not flower.
I’ve found this is more common with indoor germaniums, as gardeners put a saucer or decorative outer pot to stop water draining out of the bottom of the pot and onto their furniture. Always ensure water can flow out of the pot so that the soil does not become waterlogged.
Whenever I pot up geraniums for outdoors I always use a pot of around 12 inches across to ensure that my pot holds enough soil and moisture for the geranium to survive and flower of course!
I found that when I lived in the hotter climate of California (which, from my research, appears to be hotter and dryer than the specific area geraniums are native to in South Africa), my smaller pot (which was less than 10 inches across was drying out far too quickly on the hot and sunny Summer days.[
So I had to find a solution which was 3 fold…
My Pro Tips for growing geraniums in warmer climates:
- Use a pot that’s at least 12 inches wide so that your geranium has enough soil. A larger pot can hold moisture and not dry out too quickly on baking hot days.
- Plant your geraniums in a lighter-coloured ceramic pot. I like ceramic pots because they are thicker than plastic, and the soil doesn’t heat up as much compared to plastic pots.
- Using a lighter-coloured pot helps to reflect the heat and sun away from your pot. In my experience, dark brown or black pots dry out as much as 3 days more quickly than a lighter-coloured pot.
These three tips ensured my potted geraniums could cope with the scorching heat in Summer, and my geraniums flowered much better the following year compared to the previous year (in which the geraniums were planted in a small pot and too busy battling the heat to flower!)
Another thing I’ve noticed about potted geraniums is that some fertilizer is very helpful for flowering.
This is because the roots of the geraniums can easily exhaust the pots of nutrients. Both miracle liquid fertilizer, tomato feed and liquid seaweed work well, but I am currently favouring liquid seaweed for the time being as this prevents the problem of too much fertilizer preventing flowering, which is something we’ll talk about more in this article!
Not Enough Sun
From experience, the most influential factor for promoting germanium flowers is the hours of sunlight per day.
If your geraniums aren’t blooming, ask yourself, how many hours of sun do they see in a day?
I’ve always had the best blooms when I’ve planted my geraniums in a location with at least 6 hours of sun per day.
The one thing that we have to remember is that too much shade causes geraniums to grow leggy, and display far fewer flowers.
When I lived in California, I personally found that my geraniums thrived in the Morning sun followed by afternoon shade.
In cooler climates such as the Pacific Northwest or the UK, geraniums flower best in full sun, whereas in hotter climates such as Southern California or the Mediterranean, my germaniums appreciated some protection from the searing midday sun, hence the preference for morning sun followed by shade.
So, my advice is to judge where to locate your geraniums according to your climate!
If your geraniums are not flowering, move them to full sun if outdoors and to a sunny window indoors so the geraniums have the energy required for flowering.
Too Much Fertilizer
So, I think this is probably the most common reason I’ve seen for geraniums not flowering: people are heavy-handed with the fertilizer.
More isn’t necessarily more when it comes to geraniums! Geraniums are not necessarily heavy feeders, so fertilizing too frequently or with too much concentration can promote foliage growth at the expense of flowers.
This is particularly the case with high-nitrogen fertilizers.
So my advice on this was initially to scale back the use of fertilizer to, at most, once every two weeks with a well-balanced general soluble liquid fertilizer, ensuring the ratio of Nitrogen, Phosphorous, and potassium is even (10:10:10 NPK).
However, I have been experimenting more with different fertilizers while growing my geraniums. While commercial fertilizers such as Miracle Grow worked well, using a tomato feed or liquid seaweed fertilizer actually worked better in terms of more flowers that lasted from Spring until Fall.
From my research, I’ve discovered once flower buds begin to emerge, geraniums display more flowers with a fertilizer that contains a higher concentration of potassium (as potassium encourages flowering).
Feeds for tomato plants contain a good amount of potassium and are great for promoting germanium blooms. Alternatively, you can use a specific product for geraniums available from Amazon and garden centres that is higher in potassium to promote flowering.
In my experiment, the tomato feed and liquid seaweed had a better flower display (than the commercial brand fertilizer), but the geraniums fertilised with tomato feed and liquid seaweed were comparable without any significant differences.
I actually prefer using the liquid seaweed as it is organic and you can even make it yourself iif you live by the coast!
Cool Temperatures
So, while most of us think of geraniums as a plant that primarily flowers from Spring to Fall (which it does in most climates, as we discussed), geraniums can flower all year round in optimal conditions such as those in their native habitat of South Africa and only flower in cooler climates when the night temperature stays consistently above 55° F or 12° Celsius.
Therefore, the reason your geraniums are not flowering may just be that it is too early in the season, and they are waiting for warmer weather before they flower.
I want to emphasize that it’s the NIGHT temperature that has to warm up! I sometimes find when the day temperature is nice and warm; they are baffled as to why their flowing plants are not in bloom when there is no problem; it is just too cool at night.
When the temperature rises in the Spring, I first notice the grass really starts to grow much more quickly, and then the flowering plants start to flower all at once.
Once the weather stays consistently warm, geraniums can flower all summer until the temperatures decrease in the fall (unless you’re lucky enough to live in a really warm climate similar to South Africa!).
It is worth noting that a significant fluctuation in temperature can stress geraniums. Moving a potted geranium from a warm house to a comparatively much cooler garden can cause shock, which can prevent flowering.
Success tip for moving geraniums outdoors: I’ve experimented with this a lot, and what I’ve found works is to move geraniums outdoors for a few hours a day for around 2 weeks, gradually increasing their time outdoors to condition them to the contrast in temperatures and the geranium is less likely to suffer shock and therefore more likely to flower.
Keep in mind that our geraniums are generally not frost tolerant and should either be brought indoors if potted or treated as a flowering annual plant in a garden with cooler climates.
I check the forecast at the start of each week to check for any cheeky late frosts! I then place my potted geraniums in my shed overnight, which does the trick!
My Tips for Soil Conditions Required for Geraniums to Bloom
As we talked about, our geraniums are drought and heat-tolerant, but they require particular soil conditions to thrive and flower to their best:
- Geraniums require light, friable soil to allow for root respiration and good drainage (they do not tolerate damp soil). Before planting, amend the planting area with multipurpose compost and avoid naturally boggy or damp areas of the garden. (If you have a boggy garden, just plant geraniums in pots!)
- Heavy clay soils, compacted soil, and slow-draining soil are not favorable for growing geraniums, so you should plant them in pots, containers, or hanging baskets instead.
- The more sandy or low-nutrient your soil is, the more fertilizer is required for geraniums to flower. An all-purpose general fertilizer is suitable for geraniums; however, as we discussed, once flowers emerge, a high-potassium fertilizer (such as tomato feed or liquid seaweed) promotes more flowers throughout the Summer.
Geraniums are more likely to display a good number of flowers in well-draining light soil amended with lots of compost (and fertilizer).
Do you have any more questions about geraniums? Do you have any insights of your own? Please do share them in the comments below, and if you have a specific problem I’ll reply! I love to solve horticultural problems!
Key Takeaways:
- Geraniums do not display flowers if the soil is consistently damp, has too much shade, is fertilized with high nitrogen, has cold temperatures, or is in small pots with limited nutrients.
- Geraniums require well-draining soil, full sun, potassium fertilizer, and consistent temperatures above 55°F (12 °C) at night to flower.
- Geraniums are from South Africa and prefer somewhat dry soil between bouts of watering to thrive and flower.