Starting New Pelargoniums From Cuttings

Photo: mariakaynova, gardeningknowhow.com

Pelargoniums, also called geraniums, are popular garden plants, grown mostly outdoors as annuals. Indeed, the very popular zonal pelargonium (zonal geranium, Pelargonium × hortorum) is one of the mostly widely grown bedding plants in the world. Of course, there are many other pelargoniums, including ivy pelargoniums (P. pefltatum), regal pelargoniums (P. domesticum) and a whole host of scented pelargoniums, including the popular rose-scented pelargonium (P. graveolens).

Many pelargoniums are grown from seed, but even more, especially established varieties, are multiplied by stem cuttings. Some have been handed down this way for generations! However, they’re not the easiest plants to root from cuttings, so it can be worthwhile looking into how to best succeed with them.

Even under the best conditions, with the most meticulous care, pelargonium cuttings are not foolproof. A certain number always end up succumbing to rot. So, always take extra cuttings: about a third more plants than you really want. If ever they all root, you can always find a fellow gardener willing to take your surpluses.

? Helpful Hint: While home gardeners traditionally take cuttings at the end of winter (late February and March) in order to have a plentiful supply of plants for the summer garden, don’t forget to take cuttings at the end of summer or early fall to bring indoors over winter. Cuttings take up less space indoors (and are easier to clean for the move back indoors) than adult plants, yet will still be big enough to offer some comforting bloom to your sunny windowsill over the winter.

Myths About Rooting Pelargonium Cuttings

There are a few minor myths floating around about how to root pelargonium cuttings. None is vital (the cuttings will probably root even if you do put them into practice), but the success rate will drop and do you really want that? So, let’s dispel them from the get-go:

1. Let the cut end of the cutting dry out or callus over before potting it up. 

Although this was considered the right way to root pelargoniums back in my father’s day, it turns out that this practice actually slows rooting down and also increases the chance of rot setting in.

2. Cuttings should be 4 to 8 inches (10 to 20 cm) long.

Actually, younger stems, about 3 inches (7.5 cm) long, root more readily. Older parts become woody and less responsive. 

3. Cover pelargonium cuttings with a clear plastic dome or bag to maintain high humidity. 

Most other cuttings do indeed profit greatly from “rooting under glass,” but not pelargoniums. They’re poorly adapted to humid air.

4. Make pelargonium stem cuttings at a 45? angle. 

Actually, a straight line (90? angle) is better: it leaves a smaller wound with a decreased surface area and therefore fewer damaged cells subject to rot.

5. You can root pelargoniums in water. 

Actually, this is only a semi-myth. You can do this, but it’s an extra step, since you have to pot them up into soil later anyway. Also, the success rate of pelargoniums rooted in water is lower than for those grown in soil, plus the stems become soft and bloated, subject to rot … and when you do pot up the plants, they often sink into decline and take time recuperating. It’s just … poor horticulture! 

Rooting Pelargonium Cuttings Step by Step

Here’s what to do:

Pelargoniums are never fully dormant, so cuttings can be taken at any season. That said, they do root best under warmth, bright sun and long days, so the success rate drops considerably under the winter months. Spring through early fall is the best time to root them. 

Start with a healthy adult plant. Water it the day before taking cuttings: you’ll want the stems and leaves to be well hydrated. Clean up a work space and have the following on hand:

• Pots

? Helpful Hint: Recycled pots, yoghurt containers, plastic drinking cups, etc. make great homes for cuttings, but need to be clean. The pots can be individual ones, about 2 ½ to 3 inches (6.5 to 7.5 cm) in diameter, which will allow one cutting per pot, while trays, six-packs or larger pots can house several cuttings. And if any container doesn’t have a drainage hole, just pierce one in the bottom.

• Potting mix
• Perlite or sand (optional)
• Watering can
• Bucket or bowl
• Rooting hormone
• Spoon or other small planting tool
• Pen or pencil
• Waterproof tray
• Pruning shears or sharp knife (Exacto, etc.)
• Rubbing alcohol
• Seedling heating mat (optional)

1. Prepare the planting mix. Commercial houseplant mix is fine, but some people find the cuttings root best in a lighter-than-usual mix, so feel free to add in about ¼ perlite or sand. 

2. Pour the soil mix into a clean bowl or bucket, then add tepid water and mix well. You’ll want the mix to be slightly moist, but not soaking wet, about the texture of a wrung-out sponge. 

3. Prepare pots according to the number of cuttings you want, spooning the mix into the pots and leveling it off, leaving a ½ inch (1.5 cm) gap free of soil on top for watering purposes.

4. Study the mother plant to decide where to harvest stems: there are probably several branches and each one is a potential cutting. Indeed, you can cut a pelargonium to barely more than a stub and it will grow back. You’ll find cuttings from younger green stems will root better than older ones that have started to turn woody.

5. Wipe your pruning shears or knife with a cloth dipped in rubbing alcohol to sterilize it. 

6. Cut the stem off to a length of about 3 inches (7.5 cm), making the cut just above a node (leaf joint) at a 90? angle. The cutting will later dry back slightly at the base, so you don’t want to cut just below a node, from which you’ll want roots to form, or the node will dry out too and no roots will develop.

7. Clean the cutting tool with rubbing alcohol to be ready for the next cut.

8. Clean up the cutting, removing any flower stems (you’ll want your cuttings to concentrate their energy on rooting, not blooming!), yellow or damaged leaves, etc. Also remove the lowest leaves, thus baring at least two nodes. Remove too the stipules (tiny triangular secondary leaflets) that are attached at the nodes.

9. Dust a bit of rooting hormone on the lower part of the stem with a cotton swab to encourage better rooting, especially if two or more nodes will be covered in potting mix. Oddly, very short cuttings, with only one node, actually root better without the added hormone.

10. Pinch the tip of each cutting, clipping off the soft new growth. You can do this with your thumb and forefinger or pruning shears. This will, again, help concentrate the cutting’s energy on rooting rather than stem growth. Plus, it will stimulate branching later, giving the new plant a fuller, denser appearance and improved bloom.

11. Punch a hole in the potting mix, right in the center of the pot, with the pen or pencil. Do not use your finger, as it can carry disease spores.

12. Insert the bottom of the cutting into the hole, deep enough to cover at least the lowest node (where you removed leaves).

13. Loosely fill the hole with container mix around the stem.

14. Set the pots on a tray (you won’t want water to drip on your carpet, right?)

15. Move the tray to a warm spot in partial sun or bright light, probably to a windowsill or under plant lights. No full sun yet. The cuttings do love warmth, though, so placing the tray on a heating mat can help get them off to a faster start. 

16. Keep an eye on the cuttings, watering lightly as needed so they never dry out entirely.

17. Expect to see new growth appear, a sign rooting was successful, within 4 to 8 weeks. Or you may first notice a white root or two poking out of the drainage hole. Another option is to try pulling lightly on the cutting: if it resists, you’ll know it has started rooting.

18. When they are rooted, you’ll probably want to repot the cuttings you started in group pots into individual containers. 

19. Move the rooted cuttings to full sun … and soon you should start seeing the first blooms!

20. From this point on, just treat your pelargoniums as adult plants: potting them up as they grow bigger, moving them into the garden or onto the balcony in the summer, fertilizing them, etc. 

As long as you can provide sun, you’ll find pelargoniums easy to grow. Let’s hope all those new cuttings bring you plenty of bloom