What is the best way to germinating seeds in compost?

Question

So far, I had germinated my seeds using the paper bag approach. I must say that it was quite successful. Having said that, I have an almost-zero success rate when I try to germinating seeds directly in compost. I tried to germinate spinach, radish, nigella flowers, fly trap, chamomile and parsley. Only some of the parsley and the fly trap had germinate successful. My compost mix generally consists of 2/4 compost, 1/4 vermiculite and 1/4 perlite.

I am very keen about method and I would like to have a higher success rate. Any tips how can I do so?

Answer 1

re: "Any tips how can I do so (i.e.: have a higher [genermination] success rate)?"

1. Ensure your compost is well decomposed. If it is too hot or it contains too much tannins from unfinished decomposition, it can prevent germination of some seeds. Note: Tannins are found in source materials such as walnut, pecan, oak, etc.

2. Ensure you follow the the proper sowing/planting instructions for your seeds. Proper temp, sunlight, soil, planting depth, moisture, etc can make a huge difference in germination rates. Temp is very important for many garden seeds (68°F being ideal for many seeds). The higher the soil temp above 68°F, the lower the germination rate for many garden seeds.

3. Water your seeds with captured rain water (or tap water that has been open to air for at least 24 hrs). The chlorine concentration in the tap water of some municipalities can cause adverse affects on germination & plant growth.

4. You might want to get your compost mix professionally tested. It's not so important for germination as it is for optimal seedling growth rates.

5. I have clayey soil, so I usually use 2/3 compost to 1/3 soil for my seed starter mix. I use 1/4" screened finished compost for my seed mix & it works very well. You can certainly add more expensive amendments for aeration, but I find I never need to do that for seeds. When I want more aeration for potted transplants, I just add a bit of sharp sand to my mix. Remember, ideal farm soil is 1/3 clay + 1/3 sand + 1/3 silt. I simply substitute finished compost for the silt part of the seed mix & add sand for pot mixes.

Answer 2

Spinach and Nigella do not require heat to germinate and the success rate is higher in cooler conditions - spinach is usually sown directly out doors, as soon as the soil can be worked, around 6 weeks before the last frost. Nigella can be sown in seed trays a couple of months before the last frost date and then placed in an unheated greenhouse or cold frame, or sown directly outdoors at a later date. Chamomile needs bottom heat to germinate; parsley can take up to three weeks to germinate, and the seeds are best soaked for 12 hours in warm water before sowing. Radish also doesn't require heat - some varieties can be grown outdoors during winter.

Given you've not said in what environment/cultural conditions you've been keeping your unsuccessful attempts at growing seed, this information may or may not be useful, but it should at least point out that each plant has different requirements for successful germination, so it's always best to check the precise needs for the seeds you want to grow.

Regarding 'compost', when you use that term, I'm assuming you mean seed and cutting potting compost commercially purchased. If you mean you're using your own garden compost, then for potting purposes, it needs to have been created using a hot, aerobic system rather than a cold, anaerobic system - compost produced using the latter method is not pathogen free.

Answer 3

I plant my seeds indoors in small pods (1"x1") using potting mix. So far the results are pretty good for most vegetables like chili, tomatoes, zuccini, cucumbers, etc. I was even able to germinate carrot and cilantro indoors although I hear they can go outdoors directly. I did not have as much success with green onions and basil for some reason. I did use a heating mat to provide additional help with germination. Subsequently after germination, when the true leaves appeared, I moved the plants to 4" pots and started acclimatizing them to outdoors a few hours per day. Like you, I have had limited success outdoors and it could be a result of birds eating away at the seeds so you have to watch out for them. I also think that given sufficient time the seeds with germinate and the time it takes will depend on the type of vegetable and the temperature it gets exposure to. Good luck!

Answer 4

Beware of not having too moist conditions for your germinating seeds, because your compost contains germs and other organisms that could harm the baby plants. Ideal is to have moist / dry cycles, but it depends on the seeds.

Answer 5

The main problem I see with germinating seeds in compost is that compost is often rich in nitrogen. If it has a lot of nitrogen, they call it hot. Too much nitrogen will burn plants and prevent seeds from growing.

You can successfully grow plants in a mixture of mostly worm castings with a little peat moss. Pure worm castings might work, too. Worm castings aren't 'hot'. The plants I'm sprouting in this mixture this year are doing fine in it.

However, if you want to use regular compost (instead of worm compost), you might try adding some extra potassium to the compost. Getting the potassium and nitrogen balanced should make the nitrogen much less harmful and may even allow seeds to sprout. However, if you get too much potassium, it can also prevent seeds from sprouting. Balance seems to be the key (not amount, although there is such a thing as too much fertilizer, even if it is balanced). You could also potentially add wood chips or something to the compost, since they take nitrogen to decompose (and they contain potassium and calcium). Anyway, I haven't tried amending compost to allow seeds to start in it (and I don't know of anyone else who ever has, either), but in theory, it might work, although you probably wouldn't know off the bat exactly how much potassium you would need in order to be successful. So, don't put all your eggs in one basket if you try this.