Some of you may be looking at your new (and expensive) petunias and wondering why you can’t find seed of them anywhere.
It’s pretty simple really – many of the modern hybrids are vegetatively produced from cuttings as the seed doesn’t come true (yet).
Here are the details of getting great cuttings in the home garden. Note these standards are slightly off the normal rooting system which may account for why many home gardeners haven’t had much luck with these plants.
To begin – the tip cuttings should be taken when growth is soft and fresh (pliable and not old) Take 2-3 inch cuttings and try to keep them uniform. Different heights in the same tray are going to create moisture issues and air circulation issues (leading to possible diseases) We want equal air to move around the cuttings rather than dead spots.
You’ll also find equal length cuttings will tend to grow at about the same pace so when you need more cuttings or more garden plants, they’ll all be at the same stage of development. (Plus it’s better gardening to have them all equal) 🙂
You want to have grow lights for this plant. While the first week after you take the cuttings can be at low light levels (and should be a normal room lighting) after that, you need to kick it up to grow-light levels and no – a sunny room will not mimic outdoor conditions. Too little light is going to produce a stretched out cutting that won’t grow as well.
You *need* bottom heat – between 73-77F is mandatory for rooting. This is not a plant to root in a glass of water!
You need air temperatures around the plant of 72-75F daytime and slightly cooler at night for the rooting period.
Note – this is why I normally use an old aquarium with heat mat – the soil temperatures are right and I can light and control humidity with covering/uncovering the top of the tank.
The other issue the aquarium creates is the high humidity needed for rooting this plant. Not so high as water running down the sides of the aquarium but higher than normal room humidity.
Feed lightly at quarter strength as soon as the plant is producing new growth. Once growth really starts – move to half-strength and when going outdoors or to potting up into growing pots to full strength.
And that’s the secret – high light, high bottom heat, high humidity but not soaking wet and feeding.
Geranium cuttings but you can see uniform height, glass walls of aquarium and heat cable. FYI 🙂
So now what’s holding you back?