Growing geraniums

17 February 2022
Geraniums are something of a classic. Despite their origins in much more southern climates, it is one of our most common houseplants. With its generous flowering, it’s hard not to like!

There are a number of different varieties and species of geraniums. The most common group is zonal geraniums, which in turn have a number of sub-groups such as single-flower, double-flower, tulip and cactus geraniums. Do you know how to recognise a zonal geranium? Through the more or less visible ring on the leaf. 

A few other groups include English geraniums, scented geraniums and trailing geraniums, which we usually see in window boxes or hanging baskets. Geraniums work well indoors or outdoors in pots, hanging baskets, window boxes or flower beds during the summer. Geraniums are lots of peoples’ favourite flower, and it’s easy to understand why. 

Why sow geraniums from seed?

A geranium can live for many years when the cuttings are propagated – both in your own home and in the homes of your friends – and it’s especially nice to have sown it yourself from seed. Although sowing takes some time, it is not at all difficult to grow your own plants.


Sowing geraniums

Geraniums are best sown early in the year. If you have grow lights,  you can sow them in January or February – this will give them time to flower by early summer. If you don’t have plant lights, the daylight isn’t optimal for your seedlings to thrive until March–April.

Sow the seeds sparsely in damp seed compost. The seeds need light to germinate, but it is a good idea to top them with a thin layer of soil or Vermiculite. Completely uncovered soil makes the seed dry out easily, so it is important to keep the soil moist. Use some kind of mini greenhouse if possible (cover or lid that lets light through) to help retain moisture.

Geranium seeds grow best at 21–25°C (a heating pad is great!). They usually germinate after 4–10 days, after which it is better to leave them in a cooler place, around 18°C. If you have grow lights, you can leave them on for 14–17 hours a day.

Transplanting and moving geraniums outside

When the plants have at least two leaves in addition to the first cotyledon, you can transplant them so that you have one geranium in each pot. Use flower compost, it contains more nutrients than seed compost. Bear in mind that a small plant in a large pot can easily absorb too much water – it may be better to gradually transplant to larger pots (provided you have the energy and patience).

Geraniums are sensitive to frost, so wait until spring is here to stay and the risk of frost has passed before planting your geraniums outside. Geraniums can be planted in flowerbeds but are usually grown in pots.


Caring for geraniums

Geraniums love warmth and sun! Water regularly and make sure to feed them. If you are growing in pots, it is important to keep the soil well-drained and slightly moist for the geranium to thrive. Clay pots are beautiful but release more moisture and therefore need to be watered a little more often.

Remove wilted inflorescences as you go along and your geraniums will continue to bloom. Also make sure to feed them throughout the summer until a few weeks before you bring the plants in for winter storage.

Overwintering geraniums

Geraniums are sensitive to frost and many people choose to grow them as annuals, but they are well worth saving over the winter! Geraniums that survive the winter often grow larger and more beautiful, and you can get more plants by taking cuttings from them.

Access to a cool room of about 8–10 degrees and grow lights are optimal for overwintering geraniums, but most geraniums do well in a slightly cooler room next to your brightest window. Water sparingly and do not feed if the geranium is dormant.

Tip! If your plants are flowering at room temperature and with grow lights, you can give them some plant food. The same applies if you grow geraniums hydroponically during the winter. 

If you have your geranium next to the window, you’ll see when it comes to life! In March, light begins to return to most of the country and your dormant plants start to grow. If you have them in a cool room, now is the time to get them out. Take the opportunity to prune tired branches and possibly transplant with some extra soil.


Taking cuttings from geraniums

Although geraniums usually overwinter nicely, the plants can get a little tired after a while. Taking geranium cuttings simply means making new plants from the old ones. That way you get more plants without having to start from scratch!

The best time to take cuttings is in the autumn. Take cuttings from your strongest plants that are still growing. The cuttings will need some time to take root. Place the cuttings in water or soil – opinions differ as to which method is best, but both work.