Capillary mat?

[Lefty]

Is this of any use in seed germination? I've had issues with the 'soak the substrate till it can't hold more' technique. In the baggy method, evaporation condenses into pools of water. Ideally one wants it back in the substrate.

BTW how well do capillary mats work? Is a wick into the pot used? I looked on Ebay and the most common mat is black and comes from China. Variously described as "felt" or "cloth" it measures 120cm x 100cm x 3mm. Anyone used it? Does it rot?

[Lefty]

Perhaps I shouldn't be too worried about pooling in the bag after seeing this video of a commercial grower in Thailand. His methods appear to contradict convention wisdom about excess moisture. Granted his methods are different e.g. the pot is mostly coconut husks with very little growing medium. Even so, I have to say I was shocked. Perhaps the hot/humid climate allows for this.

https://youtu.be/uY1UcdvzbC8
(has English subtitles)

Also found this, which is similar, but on a smaller scale:

https://youtu.be/1RiWSFfOUBw

[FredBW]

In my opinion the baggie method is the way to go for starting seed. Especially if you have a heat mat and grow light. They say cactus seeds need light,but I used to set tomato seeds in seed starting mix in a tuperware bowl. Sit it on top of the hotwater heater for a few days with no light,and when they sprout THEN put them in light. (Point being germination needs heat). As long as the soil is sterile you can grow cactus seedlings in baggies for months depending on the variety.
BUT once the bag is open and they get acclimated to the dryer air you can't go back to that kind of humidity.
That is where a capillary mat comes in. I have a couple cacti and succulents that live on the mat 24-7 and thrive. But for watering seedlings it flat out works. As long as there are holes in the bottom of the pot and the soil somewhat touches the mat it will draw up moisture. There is a short learning curve to get used to the weight of a dry vs damp pot. A wicking cord will take some guess work out if you want. I have had plants the roots are firmly attached to the cord. Most of my pots don't have cord though. I don't think I have lost a cactus yet from overwatering on a wicking mat.
Here is the setup I made a little over a year ago. It still has the original mat. Just rinse the algae off every month or so and clean it out.
https://cactiguide.com/forum/viewtopic.php?t=47386

[Lefty]

Thanks for the link to your thread. Very informative. I didn't know which mat to buy and ordered a length from a horticultural supplier who claims 'commercial quality'. Will see how it goes. My intention was to just water the mat, but after seeing your simple setup I may try that. I can usually germinate seeds ok but keeping them alive and growing has been a challenge. The capillary mat just might be what I was missing...

[Andrzej1972]

I experimented with capillary mats and abandoned this idea. For me, the string bag method works best for germination and the first months. After opening, I water before soaking once a week so that the surface is dry and only moisture appears about 1 - 2 cm below the surface. I have propagators with a temperature of approx. 28 - 30°C and LED lighting. This works best for me.

[Lefty]

I have humidity issues mid summer. Germinating indoors there's little ventilation and they succumb if I don't move them out. I'll try a couple things this summer and see what works best. When you said 'string bag' was that a typo? I previously used ziplock bags just large enough to accommodate the pot (6x6cm). Not sure if that added to the humidity problems. This year I'm using a bag 2 or 3 times the volume. I'll also try using less potting medium (as in the Thai video) and captan fungicide.

[greenknight]

Cactus seedlings like 100% humidity in the early stages - fungus likes that, too. Humidity won't kill the cactus seedlings, fungus will.

[Lefty]

Cactus seedlings like 100% humidity in the early stages - fungus likes that, too. Humidity won't kill the cactus seedlings, fungus will.

Prompted by a YouTube video I once tried small plastic food containers (100 ml or so) using nothing but vermiculite. Same problem. The only variable was climate.