Poor seed germination - what am I doing wrong? Solved

[DrMikeOxgreen]

I’m very disappointed with the lack of germination from this year’s seeds from the BCSS distribution. I wonder what level of success other people get with the BCSS seeds - are the seeds not very fresh, or am I doing something wrong?

I sowed the seeds on 21st January. I know this is very early, but I have a heated propagator and artificial light. Here’s what I did:

• Soil mixture was general purpose compost mixed about 50/50 with sharp sand. I baked the mixture in the oven (much to my wife’s annoyance) at 120°C for about an hour, then cooled.
• Pots are small, about 3”.
• I sowed the seeds onto the soil surface and covered with a very thin layer of vermiculite - only just enough to hide the compost.
• Soaked the pots in tepid tap water until the surface appeared moist, briefly drained and then put the pots into sealed polythene bags.
• Put all the pots into a heated thermostatic propagator, and placed a thermometer in there as well. Temperature is about 23-25°C, occasionally rising to 26°C. The propagator’s temperature control is at its maximum, supposedly 28°C but I don’t think it’s really achieving that.
• The propagator is underneath the staging in my heated greenhouse, getting very little direct sunlight. An LED growlight hangs above, on a 12 hour cycle. Light is filtered through a layer of bubble wrap on top of the propagator lid.

So here are the results so far, in descending order of success:

• Frithia pulchra - virtually 100% germination within a few days. Seedlings are minute, but a nice bright green.
• Self-collected seeds of Puya mirabilis - don’t know how many i sowed, but loads of them popped up in a few days. The seeds came from a pod on a plant I grew from BCSS seeds a few years ago.
• Neoporteria brevispina - four seedlings. All a nice bright green and not going pink.
• Lithops optica ‘rubra’ - two seedlings. Disappointed not to get more. I always suspect that such tiny seeds don’t have a long shelf life.
• Pachypodium lamerei - two chunky seedlings, a nice green colour. Disappointed with only two - last year I got 7 or 8 gaeyii seedlings. I planted these seeds slightly deeper, being quite big.
• Ariocarpus retusus - nothing yet, but I understand these can be slow, and perhaps they need to be warmer?
• Aztekium ritteri - nothing yet. Okay, I know these are generally unreliable and difficult to germinate.
• Echinocereus triglochidiatus - nothing yet. Slightly surprising.
• Lobivia forgottenthenamei - nothing yet. Should have germinated by now?
• Two species of Rebutia - nothing. Fresh seed should have popped up in a few days, I’d have thought.

Is this about what you’d expect, or would you be as disappointed as I am? The Rebutia and Lobivia are particularly surprising; but I suspect both would have to be good fresh seed for success.

I won’t give up on them yet, especially the Ariocarpus and Aztekium, but it’s been a month now and some of the other species really should have germinated by now, I’d have thought.

Any thoughts gratefully received!

[Stuart]

The easiest part of seed raising is germination, with moisture and some warmth most seed should germinate. If not then the problem is probably the seed itself. Most problems are following germination with damping off, too much or too little light etc. Lithops and most mesemb seed viability lasts for years whilst Pachypodium seed viability is probably measured in months. Most cactus varieties should show signs of germination between one and two weeks. It's all a bit of trial and error with seed-raising though the poor Lithops germination is unusual, the BCSS seed sources usually would be reliable.

Stuart

[habanerocat]

Is the surface of your compost still wet?
With obvious condensation inside on the surface of the bags?

If so it's most likely the seed.

The only time I had poor germination was when I added a fungicide (cheshunt compound) before sowing.
Surprisingly then I had 110% germination with Opuntia but virtually nothing else came up.

[MatDz]

I can comment on the temperatures part, esp. for Mesembs (Lithops here), an adequate day to night difference is crucial. I sowed some Conophytum and Lithops a couple of times, and they were doing nothing for weeks and only started to sprout when I figured out how to get the nighttime temperature down to about 10-12C.

[DrMikeOxgreen]

The easiest part of seed raising is germination, with moisture and some warmth most seed should germinate.

I agree! The mistake I usually make is too much light, resulting in the seedlings going pink or even purple - and then development seems to stall.

Is the surface of your compost still wet?
With obvious condensation inside on the surface of the bags?

There’s always condensation inside the bags that I have to dislodge before I can see anything through the polythene. Will check whether the actual surface is still moist. Perhaps it’s worth opening the bags and giving a quick spray to be sure.

I can comment on the temperatures part, esp. for Mesembs (Lithops here), an adequate day to night difference is crucial. I sowed some Conophytum and Lithops a couple of times, and they were doing nothing for weeks and only started to sprout when I figured out how to get the nighttime temperature down to about 10-12C.

Ah, I had vaguely heard that a diurnal variation can be useful for some species. I’ll have a hunt around and see if I can find a spare time switch that I can put the propagator on and have it switch off for a few hours each night. The greenhouse temperature is maintained to a minimum of 8°C, so it won’t go below that. Thanks for the suggestion!

[esp]

Try playing around with temperature - sometimes a few 30deg C days may help. Rebutia may prefer rather lower temps.

I find with cactus, few types germinate in only 3-4 days (Frailea, Astrophytum for example), many types start germinating in around 7-10 days.
Others take longer, I've had batches of some species that take over 3 weeks before there is much germination. Even after 5 or 6 weeks, there is often occasional germination.

Opuntiods are different - they may be much slower, or erratic.
A few others (e.g. some Mammillarias) may need aging for a few years or other species treatment, but germination is generally not a problem for most viable cactus seed.

[DrMikeOxgreen]

Try playing around with temperature - sometimes a few 30deg C days may help. Rebutia may prefer rather lower temps.

Will do. Perhaps I’ll try bringing the Rebutia seeds inside the house to a windowsill and see what happens.

I’ve found an old electromechanical timer that seems to work, so I’ll plug the propagator into that with an ‘off’ period of a few hours in the middle of the night.

But is it all too late now? Do seeds lose their ability to germinate after they’ve absorbed water, if the conditions weren’t right for germination at that point, or can they still germinate now if I get the temperature sorted out?

[edds]

Definitely not too late - a few might be 'shot' but others will still be viable.

I do 12 hours on and 12 off with my propagator so the temperature properly fluctuates (it is in a cold room in the house though so always above around 14oC).

I find big differences in the speed of germination within the Echinopsis hybrids I sow. Some are through in 10 days or less, some are erratic and germinate a bit at a time and some seem to come through en masse after 4 weeks or more so definitely don't give up hope. Sometimes seed will even germinate after a full year or more in a pot so plenty of time to see some signs of growth.

[SimonT]

I use the baggy method on a windowsill over winter with supplementary lighting. I have a bag with some Mammillaria seedlings that are almost 4 months old- seed sown at the start November. A few days ago I topped up the water in the bag and today there is a new seedling. It is odd, the compost was a little bit dried out but still damp before my top-up. And there was still plenty of condensation on the bag even before I did the top-up as well.

[Aiko]

If things don't germinate, you might like to restart a few times in the coming years. After the first try in April, I usually let the pots dry out for a few weeks and retry them later in May. This is for cacti. Many African species you can count one month earlier. If still no success, they will get a retry next spring again. I continue doing this until I get the idea the soil is too crusty or too much overgrown with algae.

When you are about to give up, go for a full on approach: this is placing the pots in a layer of water so the soil gets soaked thoroughly. Keep the pots in a layer of water for many weeks. May is a good months for this, nice and warm. This might still cause good germination rates even after a few years of retrying! Still you need to have a bit of patience, might still take weeks. These last few sentences concerns seeds of cacti. But maybe works for succulents in general too.

Whatever you do, don't give up too early. Never throw the pots away after just one try.