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Having trouble with geraniums not blooming? Unlike pelargoniums, true geraniums are perennials so they spread and therefore need to be divided periodically. They also have specific temperature requirements and aren’t as easy to care for as pelargoniums.
If you aren’t sure of the type of geranium you have, true geraniums have a flat-surface flower with five petals, and a pelargonium has two tiers of petals – three lower and two upper petals. The flower size on geraniums are smaller than those on pelargoniums, too.
True geraniums are nicknamed “hardy” because they can survive winter frosts, making them perfect for the garden.
The idea of being able to keep your garden flowers in the garden all-year is favorable, but the trade-off is that true geraniums do not bloom as much as an annual pelargonium does.
However, despite having a shorter bloom season, there are some gardening tricks you can use to get more flowers from a hardy geranium, often extending its flowering season to early fall.
3 Things Hardy Geraniums Need to Produce More Flowers
1 – Cut back after the first flush of flowers
True geraniums (should) start to flower in early spring. By late spring, early summer, the first flush of flowers starts to die off. That’s just the nature of the plant. It flowers sporadically from early spring to late summer.
When it is in bloom, it’s good practice to dead head spent flowers (covered below), but in addition to that, it also helps to get rid of some of the established parts of the plants to encourage fresh foliage and healthier stems.
After the plant has put out its first flush of flowers in early spring, you can cut it back to just 2” to 3” above ground level. It’s best to only do this after the first flowering to get a second burst of blooms.
By the end of summer, early fall, the plant will go dormant over the winter so there’s little reason to cut it back at the end of the year.
Depending on where you’re located, you could have superb foliage on your geraniums over the winter as they are only deciduous in colder climates where temperatures drop below 60oF. Above 60oF and they’ll maintain foliage.
2 – A high-potash fertilizer should be added after cutting
To stand the best chance of a second bout of blooms after cutting it back, add a slow-release granular fertilizer that’s high in potassium because that’s what helps strengthen stems and lends an assist with bud formation too.
Naturally, for your geranium to bloom, it needs buds to be formed on strong stems. That’s why it’s always recommended to use a high-potash fertilizer on geraniums and pelargoniums.
As a rule of thumb, go easy on nitrogen rich feeds because you want the plant’s energy entirely focused on flowering and not growing more leaves.
3 – Prune and deadhead throughout the flowering season
Geraniums are usually sold on the premise that they’re easy to grow and care for. A claim that’s often mistaken for maintenance-free, something these plants are a far cry from.
To get the best blooms, you need to continually get rid of spent flowers and carefully prune spindly stems to prevent buds forming on leggy stems.
The problem with thin and straggly stems is they don’t have the strength to support large flowers. In most cases, any flowers that do form on leggy stems droop because the stem doesn’t have the strength to support it.
Rather than waiting to discover that, prune the straggly stems away. If you’re unsure if a stem is going to be of any use, gently pinch it. Stems should feel firm when you squeeze it with your thumb and forefinger.
The reason you want to be removing spent flowers (dead-heading) early is so that the plant is putting as much of its energy into flowering as possible, rather than foliage growth.
As soon as you notice the colors fading, it’s time to remove it. Do that by following the stem from the flowerhead to the trunk and either cut the stem where it joins the trunk using a pair of sharp pruning shears, or gently push it backwards until you hear it crack.
It’s also advisable to be smart with your pruning by removing young buds early. Keep the thicker stems intact, and remove the thinner stems, and certainly get rid of any leggy stems because any flowers that do bloom on a leggy stem won’t be anywhere near show-stopping.
The 2 Most Common Causes for Geraniums Not Blooming
1 – Inadequate sunlight and temperatures
All types of geraniums (including pelargoniums) are best suited to warm climates.
However, in the case of the hardy geranium, the University of Massachusetts found that they respond best to what’s referred to as a fast-cropping technique, which is having temperatures maintained between 70oF and 75oF in the daytime, and 60oF to 65oF at night. When temperatures drop below 60oF, geraniums don’t bloom well.
Additionally, heat-stress can kick-in when temperatures rise above 85oF. If left in soaring heat for longer than 12 hours, it results in a loss of chlorophyll leading to stunted growth. Night temperatures below 60oF also slows growth.
Despite being planted in the garden, there are things you can do to shelter geraniums from hot afternoon temperatures and substantial drops in temperature at night.
For heat protection, aim for shade. A lot of gardeners plant their geraniums where it’s likely to get the most sun. They do best with 6 to 8 hours of full sun daily but that doesn’t take into account for heat waves when the temperatures are above what a geranium can tolerate.
On hotter sunny afternoons, water your plants to cool them down, being careful to water little and often as they don’t fare well with moist soil.
A good way to protect plants from heat stress is to apply a thick layer (about 2 to 4 inches) of reflective mulch such as dry grass clippings. It doesn’t protect the leaves from direct sunlight, but it will prevent the soil from heating up as fast, and it’ll keep the soil moist for longer as the water you do add won’t evaporate as fast.
An alternative way to protect garden plants from rising temperatures is to use sun covers to provide temporary shade.
To protect geraniums from spring frosts, water works wonders because it can hold heat better than air. The goal for gardeners is to retain as much heat in the ground soil as possible when they know there’s a frost due.
One way to do that is to water the soil during the day so that it absorbs the heat. As the temperature drops overnight, the water will be vaporizing, helping to increase the temperature around the plant.
Another way to increase the temperature is to use hot water bottles. Not the type you take to bed or snuggle up with, but jugs, jars, containers, or empty milk cartons filled with warm water.
You can place containers with warm water around your plants to increase the soil temperature and provide some thermal insulation to prevent a cold snap from causing damage to your plants.
2 – Maybe it’s just old, in which case you need to divide it
Hardy geraniums grow in clumps, and being perennials, they spread. In just a few years, they can spread as far a few feet so every three to five years, what happens when you don’t divide them is each clump ends up competing for nutrients and there is no winner.
The end result is a wider shrub with stems and leaves straddling all directions with not much flowering happening on top.
More blooms from older geraniums are only possible when you divide them. If your geranium has stopped blooming after a few years, it’s likely that it’s spread too far causing it to struggle to get the nutrients it needs from the soil.
If you have geraniums not blooming, or blooming with fewer flowers than they usually would, or if the flowers and the leaves they produce are smaller, that’s a sign of maturity. Younger plants grow faster.
How to Divide Geraniums
Geraniums are best divided on a day that’s cloudy and cool to avoid the plant from drying out. It can be done any time of the year, however, for the best chance of blooming, if you divide the plants at the end of the year and transplant them, it’ll give the younger roots enough time to get established, helping to speed up the time it takes for it to begin flowering in spring-time.
To divide geraniums, use a sharp spade/shovel and dig around the root zone making sure you can get the spade/shovel under the entire plant. You don’t want to lift one clump. You want to lift the entire plant out of the ground. Once you have it lifted, you can then use a sharp gardening knife to split the roots.
Keep in mind that geraniums have both underground running roots (horizontal) and taproots (vertical) when you’re digging. The running roots are what they use to spread.
The taproots are the important ones for geraniums to take up nutrients from the soil so try to avoid damaging the taproots when lifting the plant out the ground, and divide them by cutting the horizontal roots using a sharp gardening knife to divide them.
Once divided, you can either pot them up in soil, or transplant them into another suitable part of your garden ready to start producing more blooms next spring and summer.