Seed-raising guide
Growing cacti from seed for beginners (Or, how to succeed moderately well with minimum fuss!)
As in all areas of this hobby, I wouldn’t dream of claiming to be any kind of expert. And where seed-raising is concerned, I’m only just past being a beginner. However, I’ve sown such a lot of seed and made so many mistakes in the past 12 months – and continue to make new ones all the time! – that I’ve settled into something of a routine, which I thought it might be worth sharing.
A good piece of advice I was given when I began exploring seed-raising is not to set your sights too high. Some genera are notoriously stubborn to germinate (e.g. some opuntias, sclerocacti etc.), and others are difficult to keep alive as youngsters. If you begin with difficult plants you may find yourself discouraged by the results. Good genera for starters are things like Mammillaria, Notocactus, Gymnocalycium and Echinopsis and any of the rapid-growing cerei.
For this recipe, you will need:
- Some plastic labels
- 1 waterproof marker pen
- John Innes No. 2 compost
- Tesco’s Premium Lightweight cat litter or equivalent non-clumping clay-based litter
- pots
- sealable clear polythene bags
- a microwaveable container
- a large cup of coffee, and…
- SOME SEED!
Make sure your pots are clean. I give them a good wash with hot soapy water. You can go further than this if you want to but I don’t generally find I have any real problems arising from not having exercised any greater caution.
The next thing to do is mix some growing medium. I’ve gravitated to using a 50-50 mix of compost and cat litter. I have no scientific reason for doing so, but it feels about right to the touch – it’s nice and light and airy. You may prefer to use perlite or fairly fine grit instead of cat litter if you have difficulty getting hold of it or are worried that your feline friend might think he has a new litter tray.
Now it’s time to sterilise the compost to kill off any nasties that might be lurking in it. Put the mixture in the microwaveable container, and set your microwave oven to “thermonuclear” for ten minutes. The cat litter absolutely reeks when cooked, so you might want to open a window or invest in some strong air-freshener if your partner is likely to object!
If your microwaveable container turns out not to have been microwaveable after all, you will find that the super-heated compost will have burned a hole through the bottom of it as per the next illustration. Compost gets very hot when microwaved. Carte d’Or ice cream tubs are not microwaveable, as I found out today.
While the compost is cooking, use the time to write your labels. If the seeds come with field numbers, then the important thing is getting that right. Also, do write the date on the label.
There will come a point whereby you will want to see how well the seedlings are doing relative to their age, and once you have sown a few batches of seed there’s no hope of remembering when you put them in. Use chopped up pieces of labels – they fit in the plastic bags more easily.
Let the compost mixture cool until you can handle it and are sure that it won’t melt the pots you are going to use. Run cold water into your sink so that the pots can sit in it without water pouring over the sides. Needless to say, I usually get this wrong.
Fill the pots with compost, and then stand them in the sink to take up water so that they are evenly wet through.
Remove the pots and stand them on the draining board to drain. It’s important to add the labels now, before you start the actual business of sowing.
Pushing the label into the pot compresses the soil quite considerably, and can quite easily take stray seeds down into the depths of the pot, never to be seen again.
Nearly there.
Now it’s time to sow the seeds. With cactus seeds I tend to tip all but the tiniest seeds into the palm of my left hand and use thumb and forefinger of my right hand to pick them up and sow them. Smaller, more dust-like seed tends to get scattered more randomly, which does unfortunately tend to lead to seedlings growing rather bunched up. But they don’t seem to mind too much.
I sow small seeds directly on the surface of the compost. There is no need to cover them, as they are quite capable of absorbing the moisture they need from the humid atmosphere. Seeds like these of Tephrocactus fiambalensis nom. prov. are HUGE and need to be buried.
Just use a pair of tweezers (or, if like me your tweezers tend to find their own place in the greenhouse regardless of where you last put them, the point of a pencil will do) to make pits in the compost just deeper than the seeds. There’s no need to go mad and burrow down to the bottom of the pot:
After you’ve sown the seeds, seal the pots individually in their own sealable plastic bags. This will maintain humidity and ensure that you don’t have to bother about watering them all the time to keep them moist. That comes later.
If you have used longer labels, seal the bags so that the side of the pot with the label is at a right angle to the seam of the bag. Trust me, it’ll make it much easier to close the bag without disrupting the contents of the pot.
Place the pots under artificial light, with bottom heat, if you’re sowing outside of the normal growing season – otherwise a nice bright windowsill or under the greenhouse staging will do fine. Germination times vary according to species, but some will be up within days.
Now you can drink your coffee. You’ve earned it.
As I said at the beginning of this article, I don’t pretend to be an expert but am happy to answer questions.
I also realise that there are plenty of other subtle variations on this theme – some people use fungicides, whereas I choose not to as I don’t generally seem to experience problems with damping off. The thing to do is have a go, and find out what works for you. Hopefully you’ll end up with some pots that look something like this:
