Geranium macrorrhizum is commonly known as bigroot geranium, rock cranesbill and Bulgarian geranium. It is a species of hardy, easy to grow, flowering plants that belong to the Geraniaceae family.
The plant is popular as a ground cover because it looks amazing alongside other plants. Its colorful flowers, which come in purples, pink and white also add more life to blank spaces in your yard.
Interestingly, when grown on its own, it doesn’t look quite as beautiful as when its is alongside other plants. This is likewise the case in containers, which is why it’s often planted in yards, gardens and pathways.
The Geranium macrorrhizum features dark green, fragrant foliage that are 4 to 8 inches long. They’re unique in that they turn red during the fall months. This instantly brings back some color to you garden during this time of the year.
Its flowers have 5 petals of varying colors. And they bloom from early spring to late summer.
The plant itself gets to about 12 to 18 inches tall and cover a 24 inch spread.
It is native to Europe, mostly those south east of the alps.
Geranium Macrorrhizum Plant Care
Geranium Macrorrhizum Light Requirements
Geranium macrorrhizum thrive in full sun to partial shade.
- In cooler conditions or regions with cooler summers, it will do best in full sun (at least 6 hours sunlight daily).
- In warmer regions, it will be happiest in partial sun or partial shade, both of which providing 4 to 6 hours of sunlight a day.
The reason being that while it appreciates plenty of bright light and will tolerate such an environment, it will prefer some shade in the most intense conditions.
As such, if you live in the southern part of the country where summers can get really hot, it is a good idea to position it somewhere it will have a bit of protection in the peak hours.
Indoors, this means that south, west and east windows are the best spots.
Again, in cooler areas, it will do better in the south and west as this gives it more light. In warmer locales, it will perform best in the east.
So, while the plant is able to tolerate different lighting conditions, it is important to remember that it produces the most flowers and with the brightest colors when it receives plenty of light.
On the other hand, if you notice it blooming less or producing smaller blossoms, then the first thing to do is check light exposure. Insufficient light or if placed in full shade, the plant won’t do anywhere as well as it does under sunlight.
This is why the plant is often grown as ground cover, edging or around paths and walkways. These areas tend to receive lots of exposure.
You can likewise grow them in containers. But, if you do, you will need to water them more often than in the ground. That’s because they limited amount of soil in the pot means water will run out sooner.
Because of their looks, these plants are often grown in mass plantings where they stand out because of their beautiful foliage and colorful blooms.
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Temperature & Humidity
Like light, Geranium macrorrhizum does well in a wide range of temperatures and humidity. This makes it very versatile in that it can live in cooler parts of the country as well as some warmer locations.
The plant is heat tolerant. And, can take some higher humidity. This makes it different from many other geraniums which have problems with humidity that are above average.
However, you still do want to keep it away from very humid conditions. While it can take the air moisture, it will be more prone to mildew and rust there.
The good news is, these are both problematic issues you’ll need to take care of if they happen. But, they’re not life threatening to the plant.
When it comes to temperature, your Geranium macrorrhizum will grow its best when daytime temperature stay between 65 and 75 degrees Fahrenheit. At night, it will appreciate a cooler 50 to 60 degrees.
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How Often to Water Geranium Macrorrhizum
Geranium macrorrhizum are drought tolerant. Again, this makes them a lot easier to care for, not to mention lower maintenance, compared to other geranium species.
As such, this make them great color options for rock gardens and xeriscapes where you use very little water. They likewise won’t have an issue growing in dry conditions.
That said, be aware that younger plants need more watering as the grow faster. Once established, your Geranium macrorrhizum can tolerate drought conditions.
This is because they have shallow but dense root systems. Thus, it is still a good idea to water them regularly to produce the best growth. This is especially true when they’re blooming.
But, don’t overwater. Nor do you want to let it sit in water.
Ideally, allow the soil to dry between waterings. They likewise respond best with deep watering where you add water to the soil until it won’t absorb anymore.
This will make the roots work harder. And, in the process develop a stronger, healthier root system.
A few final things on watering.
- Avoid watering from overhead where you wet the plant’s foliage. This will increase their risk of fungal infection which they’re already prone to.
- During hot summers or if you live in warmer areas, you’ll need to water regular.
- Growing the plant in containers also means more regular watering compared to those in the ground.
Soil for Geranium Macrorrhizum
Geranium macrorrhizum are likewise not picky about soil. But, for the best results, give it fertile, moist and well-draining soil. It also grows best in slightly acidic to neutral soil.
That said, the plant won’t mind other soil types. And, will make do with almost any kind of soil you give it.
What I mean by this is that:
- It can tolerate both clay and sandy soil
- It won’t bother if the soil is mildly alkaline. As long as pH is between 6.1 to 7.8, it won’t have any problems.
- It can tolerate dry soil, even it moist is optimal
As such, like many of its other aspects above, it is very easy to care for because it tolerates a very wide range of levels.
If you had to choose one thing to focus on with soil, it would be drainage.
Make sure that it the soil drains well in order to prevent root rot. This also alleviates the problem of having to gauge how long before you need to water again.
If you’re not a fan of regular watering, use mulch. This will save you water over the long run as it helps water from drying out too quickly without allowing the roots to sit in water. It also reduces weeds.
As mentioned above, Geranium macrorrhizum enjoys rich soil.
While you can use a good dose of fertilizer to help it grow its best, I’ve found it better and safer for plants if you take a little more time to work on the soil.
This reduces the chance of fertilizer burn. And, it will save you money in the long run.
What I mean by this is adding organic matter to the soil in advance. Compost is a great option because it loosens the soil and improves its quality. It also adds nutrients.
And, if you do so, you won’t need to use fertilizer anymore. Instead, all you need is to add a yearly layer of compost in the spring. This will be enough to keep the plant happy to grow and bloom at its best.
The best time to start is around winter. By adding plant manure or compost to the base of our Geranium macrorrhizum, you’ll give the bacteria and earthworms enough time to do their work.
This will make the soil ready when you plant.
Outdoors, the only time you’ll need plant food is if you have poor soil. Here, use a balance (10-10-10) fertilizer, preferably slow-release, during the spring. This will cut down on the work.
If your Geranium macrorrhizum is growing in a pot, you’ll need to make sure you give it fertilizer since more potting mixes are soilless. As such, they don’t contain minerals.
Use the same application as above.
For most hardy geraniums, it is a good idea to cut them back to the ground after they bloom. This improves their chances of reblooming. It also fixes the problem of sometimes being difficult to deadhead them.
But, with Geranium macrorrhizum, this is not the case. After the bloom from late spring to early summer, the flowers will then fade. At this time, early deadheading is a good idea is it keeps the plant looking good. Plus, it reduces the possibility of self-seeding.
If you don’t deadhead the flowers, your Geranium macrorrhizum’s natural instinct is to self-seed soon after. This makes them aggressive growers, although non-invasive. As such, allowing them to do so will result in them growing all over your garden.
That said, this may be a good idea in blank sections of your yard where you want them to provide ground cover. If so, allow them to propagate on their own.
Geranium Macrorrhizum Propagation
Geranium macrorrhizum can be propagated from cuttings, seed, division or separation. This gives you many different options to choose from. And, you can go with whichever you prefer and get the highest success rates.
Do note that the plant self-seeds. As such, if it does and you allow it to, they will develop into fully-grown plants over time. As such, you won’t need to propagate them.
Of the different options dividing is often used because it works best. Also, dividing the plant every 3 to 5 years helps them live longer. As such, many growers do so.
The best time to do this is during early spring or summer. This will give it enough time to establish itself before frost arrives.
How to Propagate Geranium Macrorrhizum from Division
- Dig up the plant
- Remove any excess soils around the root area
- Pick out one or more sections depending on how many new plants you want to grow.
- Start tracing down from the stems and up from the roots. You want to make sure each section has stems, leaves and roots.
- Use a sterile knife to separate the root sections from the mother plant.
- Take each section and plant them into the ground or in pots. If you grow them in the ground, keep spacing at about 2 feet between plants.
How to Plant Geranium Macrorrhizum
The best time to plant Geranium macrorrhizum is during the spring or in the fall. If you decide to grow them in the ground, make sure to leave about 2.5 feet spacing between plants. This will give them and their roots enough room to grow.
- Decide whether you want to grow the plant in a container or in your garden. Both will work. So, it really depends on what, where and how you’ll use the plant.
- The plant will do well as long as there’s enough sunlight. If you live in a warm area, make sure the afternoons get partial sun or shade. If you live in a cooler area, full sun is ideal.
- Make sure the soil is well-draining. This is key.
- If you have poor soil, amend it first with compost. It is also a good idea to aerate and decompact your garden soil.
- If you’re growing it in a pot, choose good quality potting mix. Add some perlite, vermiculite or coarse sand to improve drainage.
- Plant the seedlings or semi-grown plant into the ground.
- Water it to keep the soil moist. Regular watering is ideal. But, don’t overwater.
- Wait and enjoy its beautiful foliage and blooms.
Pests and Disease
Geranium macrorrhizum are not prone to any serious problems when it comes to pests and diseases. However, you do need to watch out for them because no plant is ever immune to these issues.
As much as every grower does not like doing this part, they are crucial in keeping your plant healthy. In fact, one instance of either, if bad enough can wipe out years of hard work.
When it comes to pests, aphids, snails and slugs are the most common problems. You may also see leaf miners.
Diseases are likewise something you want to avoid. Many of these are moisture related. So, keeping water in check, not watering over the leaves and keeping the plant away from high humidity are important.
The most common problems include mildew, leaf spot, botrytis, and bacterial blight.