When you can strike the right balance to mimic outdoor growing conditions, you can grow and care for any species of plant indoors, including the many varieties of geraniums.
In this quick guide, you’ll discover all you need to know about growing geraniums in pots, indoors, so you can enjoy the beautiful scents and gorgeous florals these plants can give year-round.
Growing Potted Geraniums from Seeds
With a wide variety of geranium plant seeds available, whether locally at your florists, garden center, or online, it’s possible to create a spectacle of a floral focal point using geraniums to brighten and fill your home with the pleasant and distinct aroma that geraniums give off.
They’re perfect for creating an aroma of outdoor summer, indoors. Ideal for a quiet room used for reading, relaxing, or yoga as it brings the traditional scents of outdoors, inside.
What You Need:
- Seeds and starter trays. If you’re the thrifty type, feel free to forego the starter trays and use the likes of egg cartons or used yogurt containers. The container just needs to be deep enough for two to three inches of potting soil.
- A sterile potting soil – ideal is to use a seed starting mix. If you’re making your own starter seed mix, the key ingredients to use are vermiculite, peat moss and perlite.
- For lighting, seeds will need around 10 hours light per day therefore, grow lights are preferable. You can try without them, but expect it to take longer.
- Artificial Grow Lights. (See our guide here about Growing Plants Indoors with Artificial Lights)
- Heat mat
- Dome Germination Station (Like this one on Amazon that includes the heat mat)
How to Germinate Geranium Seeds from Scratch
Step 1. Lightly moisten the seed starting mix then fill the starter tray or each plant cell.
Step 2. Place one to two seeds maximum per plant cell.
Step 3. Put a thin layer of soil over the soil, just enough to cover it, but not enough to bury it.
Step 4: Lightly water the top soil.
Step 5. If you’re using a grow dome, you can just put the lid on at this stage but if you aren’t, an alternative is to cover the plant trays with plastic wrap.
Step 6: Put a heat mat under your starter tray and grow lights over it. Geranium seeds do best at a consistent 750F / 240C. Using a heat mat helps maintain the temperature and LED grow lights placed 6” above the plant pots and powered on for 10-hours a day should see your seeds germinating in just a few days.
Step 7: Leave things be until you see green. As soon as the seeds germinate, remove the cover or plastic wrap and lightly water the soil again.
Note: If you aren’t using grow lights, the lack of sufficient light can cause your seedlings to grow leggy. If this is the case, they will need more light to strengthen them before transplanting.
Transplanting Geranium Seedlings
Here comes the tricky part… Knowing when the right time is to transplant geranium seedlings.
Timing is crucial and geraniums don’t make it easy because the first leaves you see, aren’t the true leaves. The first leaves will be cotyledons.
Here’s a brief video that shows the difference between cotyledons and true leaves:
The cotyledons are what germinates after a few days under the right light conditions and temperatures. Once you remove the lid on a grow dome or the plastic wrap, keep the growing conditions the same for another week to two weeks, which is usually how long it takes for the true leaves to form.
What You Need for Transplanting Geranium Seedlings
- 4” pot with drainage holes
- Drainage material
- Soilless potting mix
- Small trowel (optional)
Step 1: Prepare your Plant Pot
Geraniums don’t do well in standing water so the plant pot you use needs to have drainage holes and those need material placed over it to prevent them from becoming clogged, which will lead to overwatering problems.
It’s not a good idea to use gravel as a base layer as that retains moisture and heat, defeating the purpose of using a potting mix that’s specifically developed to help get rid of excess water.
Instead, good materials to use to prevent clogging in pots are a plastic mesh liner, or a mesh bag like the ones you get from the supermarket in multipacks of oranges, tangerines etc. Tea bags and paper coffee filters can be used but those are biodegradable. The only thing to definitely avoid using is wire mesh because the moisture will cause it to rust over time.
Step 2: Fill Your Plant Pot with Potting Mix
An ideal potting mix for geraniums are the soilless varieties, which just means, it’s not the same as garden dirt. Soilless mixes usually have three parts of sphagnum peat moss, which holds water, and then perlite and vermiculite which break the fibers in the peat moss up so that water passes through easier.
Fill your pot with a well-draining soilless potting mix until it’s about three quarters full.
Step 3: Remove the Seedlings from Their Tray
Ideally, use a small trowel to dig as far beneath the seedlings as you can before gently lifting it out by its leaves. Try not to handle the stems as those will be delicate. More so if they’re leggy, which is what can happen if they’ve germinated slower because of insufficient light.
You want to keep as much of the soil on the roots as possible.
Step 4: Plant Your Seedling
Once you’ve removed the entire root of the seedling, you can see the size of the root ball. Judging by that size, dig a hole that’s slightly wider than the root mass and pop your seedling in.
The roots should be kept at the same depth as they were originally grown in. Not deeper, so still keeping to a depth of two to three inches of potting mix. Once it’s planted, gently pat down the mix around the base of the plant.
Step 5: Water Until You See the Water Filtering Out of the Drainage Holes
The last part is to add water and when you do, continue watering until you see the water coming out of the drainage holes. If you’re using a saucer or something else to collect the water, dump the excess so the pot isn’t sitting in standing water, which will damage the plant.
Adding Fertilizer to Your Newly Potted Geraniums
Just like all plants, they need a good feed, but right after transplanting seedlings isn’t the time to go full on with fertilizer thinking it will spur growth. It won’t and can actually cause more harm than good. You need to break them in gently by using a diluted soluble fertilizer – nothing granular as that can cause fertilizer burn.
A good soluble fertilizer in the early stages are balanced ratios from 7-7-7 to 15-15-15, but even at that, diluted to a quarter to a half strength as the plants aren’t fully matured.
Keep in mind the numbers only refer to the levels of Nitrogen, Phosphorus and Potassium, which is all most plants need, so general all-purpose fertilizers are ideal for starting off with. After they begin to flourish, geraniums need a little extra feeding.
Adult geraniums do well with a 20-20-20 soluble fertilizer applied every two weeks. They also need a source of magnesium to keep the foliage green. A lack of magnesium can cause yellowing leaves on geraniums. Every third watering, you can use Epsom salts mixed at 1 teaspoon per gallon of water.
For best results, fertilize every couple of weeks, and add a source of magnesium every six weeks.
Keeping Geraniums in Bloom All Year
While geraniums are typically found in outdoor gardens and hanging baskets, they can flower all year. The only thing needed is enough light.
During the summer, this is easy enough as you only need a south facing window to get enough sunlight to encourage the plant to bloom. In the winter months, artificial lighting can be used to simulate the effects of the sun.
In terms of temperatures, they only need it to be above 650F / 18oC so light is the main barrier you’ll come against, which can be supplemented by artificial light for up to 14 hours per day.
When watering, unlike a lot of plants that need consistent misting or light watering, geraniums fair best when they’re drenched after the potting mix is left until it’s nearly dry, then watered until you can see water seeping through the drainage holes in the pot. Overwatering geraniums is what causes a lot of their problems such as stunted growth, sickly looking leaves and generally looking spindly, rather than bushy.
Speaking of bushy, when you’re growing potted geraniums indoors, regular pruning is essential so it can maintain its compact and bushy appearance. These plants are vigorous growers so whatever you pinch and prune will grow back.
Use a sharp pair of pruners regularly for deadheading spent flowers, and remove any yellowing leaves when you see them. When snipping, cut a 45-degree angle to help prevent infections.
Something to pay attention to when you’re snipping are the stems that cross over as those are what can make potted geraniums look overcrowded in a single plant pot.
By snipping double and crossed stems, you can mold the plant into the framework you want it to grow, which is how you’ll be able to keep your plant looking in pristine shape and producing vibrant and fragranced flowers throughout the year as each time you cut the plant back, it encourages new growth.