In putting together a system for germinating seeds, there are several important points you might want to consider.
The first is that vegetable seeds germinate when in contact with moisture. Sounds pretty simple but that’s one of the essential things to keep in mind.
We don’t bury them to put them in the dark, we cover them to ensure they are in contact with moisture. If you create those moisture-rich conditions, burying the seed is an option for most seeds. So seeds need moisture to germinate, they don’t need dark (a few flower seeds such as pansy do).
We can bury seeds slightly because it makes it easier for the roots to orient and establish themselves. The smaller the seed, the less this is necessary. So a small radish seed will flip over quite nicely, bury the root in the soil and start growing almost immediately. A bean on the other hand can be quite stupid about it and wander around the soil top for a few days before taking the downward plunge.
The rule of thumb in starting seed indoors is to just cover the seed with your seed-starting soil. Just!
If maintaining contact with moisture is one of the key criteria for getting indoor seed to germinate, then there are a few tricks you might want to consider.
In the commercial greenhouse, we use a mist system. Automatic timers would spray the seedling trays with a mist every 30 seconds or so. The seeds were kept damp but not swamped.
On the home scale, I cover my vegetable seedling area. If I’m using my aquarium starter system, a food plastic-film is stretched over the top to stop moisture from escaping. If it’s only a few or a flat, I can put them inside a white plastic shopping bag. The trick is to ensure moisture is around the seed. You’ll be surprised how little constant moisture it really takes to get a seed to germinate.
I soak all my seed pots with warm water (I mean soak) before I sow the seed. The soil is warm, soaking wet and ready.
Watering is only done when the soil is drying out – again with warm water only – and carefully with a fine rose (holey thing) on the end of the watering can. Again, I soak the pot so the soil is wet. Understand I’m not keeping it swamp-like but when I water, I do water thoroughly.
The thing about this is that the soil under the plastic isn’t going to require a lot of extra water if you start with really wet soils.
The other major need of indoor-started vegetable seeds is to be reasonably warm if you want to see good germination. I don’t start the tough seeds (spinach, kale, peas etc) indoors – they go straight to the garden.
Again, the rule of thumb is that you want the soil temperature to be around 70F.
Understand that if you don’t create that artificial soil temperature in some way, germination rates will be low or non-existent. As a little factoid, soil temperatures are usually around 10F degrees colder than air temperatures. So if your house temp is 72F, the soil moisture is around 62F. and germination is going to be low.
My simple (read cheap!) 🙂 system uses an old aquarium (25 gallon) with a 60 watt trouble light (outdoor bulb!) inside it and the plastic film over top to hold in the moisture and heat. In my trials, this holds a 72F soil temperature level. You might want to experiment with different wattage bulbs depending on the size of your aquarium or container. In fact, if you used a regular aquarium hood with grow lights, you’d probably find the temperatures would climb nicely. Leave the lights on 24/7 for the germination phase. Florescent lights don’t produce enough heat – you need the old-fashioned incandescent bulbs.
Warning- You can use any system you can devise – simply understand that a 60 watt light bulb will melt plastic film if it comes in contact with it and there is a danger of fire so do be careful when using a system such as this.
A candy thermometer works really well at measuring soil temperatures (don’t tell the cook)
In this picture, you can see I have some Turface (an oil-absorbent product) spread over the bottom of the aquarium. This is damp and hold humidity levels quite nicely for taking cuttings of annuals. I’m just too lazy to remove it for starting seeds and it hasn’t hurt anything yet.
The trouble light is hooked over the bottom left corner away from the plastic film.
I use an aquarium thermometer to measure interior air temperature – this is moisture resistant, rust resistant and tells me if the air is too hot. Once you get the wattage of the bulb right, you don’t have to worry about this too much.
And yes, if you get too much moisture hanging on the plastic film, you simply open up the film for an hour or two and it will disappear. Drops hanging on the film are a sign you have too much moisture in the tank.
I now run my entire gardening “empire” from this simple system (and yes, those are shrub cuttings and not vegetables but it was the only pic I had that showed it the way I wanted to) 🙂