Autumn seed sowing eables you to get a head start on next year. It gives an earlier crop than spring sown plants and gives that succession needed to have a continuous display. They can be sowed in a greenhouse, poly tunnel, coldframe or even in old milk jugs, and some can go straight outside either in the final cropping positions or in pots.
Choose Hardy Annuals which can withstand a little frost or colder weather and check seed packets for which months to sow. Some of my Autumn favourites include Orlaya Grandiflora, Sweetpeas, Moon Carrot, Daucus Carotta, larkspur, Poppes and Cornflower.
Let's start by saying that nothing is for sure, but given the right conditions seeds will grow. It’s very easy to get it wrong with watering, temperature and pests but it’s the cheapest way to fill a garden and will give you many blooms which are not commercially available in the garden centres. You can also ready my Beginners Guide to Growing from Seed - The Dark art of Propagation to start off with.
With autumn seed sowing season upon us I have compiled a few hints and tips along with my list of favourites for Autumn.
1. Moisten your compost first to allow greater absorbtion of water without disturbing the seeds and also to help prevent damping off. If you water onto a dry mix you will find that your seeds can easily get washed to the sides of the pot. Just a small sprinkling of water is enough, mix the compost thoroughly and then fill your pots.
2. Tamp down the soil inside your pots a little so that it is compact. Roots don't like large air pockets and will not grow well through them, also It will be much easier to push out the seedling for potting on.
3. Don’t sow seedling too thickly as this will just lead to less airflow and diseases will set in. The seeds will also have too much competition to grow strongly. Better to sow as thinly as you can so the roots have plenty of room to grow. This will also make pricking our easier as the roots will not be so much of a tangled mess
4. Check your seed packets. There are vital tips on there for each type of seed. Some seeds need light to germinate and others must not be covered at all. Use vermiculite to cover seeds rather than soil. Soil can form a hard crust on the top of the soil, especially if the seeds are taking a long time to germinate – some can take as long as 3-6 moths ! In general the smaller the seed the less cover they need with seeds such as poppies which are tiny needing no cover and sweetpeas - quite large needing to be buried quite deep.
5. Always label your seed trays with the variety and date sowed. It can sometimes feel like a long time while waiting for germination but in reality only 2 weeks has passed – which is perfectly normal. It’s also good to test your marker pen to ensure that it is permanent, I have used one in previous years and later found that it was not quite as permanent as the label said it was! If in any doubt then a pencil will work well and will not wash off.
6. Water seedlings from the bottom as much as you can. This will prevent any problems with disease and fungus growing on the surface of the soil and killing your seedlings. You can also use a cinnamon wash to prevent algae. Simply boil a pan of water with a few cinnamon sticks, wait to cool and use this mix to water your seedlings.
7. Some seeds require a period of cold stratification before they will germinate - The seed packet will tell you this. These are the most tricky seeds and there are a few ways you can do it. These seeds are very hardy and really are best sowed in autumn - this mimmicks their natural conditions. So you can sow them in autumn and just let nature do its job, leaving the seeds outside or in the greehouse over winter. The cold weather naturally kick starts the seeds and once the weather warms in spring they will germinate.
8. Damping off in the greenhouse in winter is a particular problem. It is caused by a type of fungi which need damp soil to spread from one plant to another. The best way to prevent its spread is with good hygiene. Ensure all containers are cleaned thoroughly before use, soak them in hot water and scrub off all the dirt, you can also use a disinfectant to ensure they are spotlessly clean.
9. Always use fresh mains water for seedlings as water stored in a waterbutt or even just in the watering can for a few weeks can start to form algae. Don't overwater plants in autumn as this also leads to damping off, follow tip # 1 I gave ........Moisten your compost first rather than dretching the seeds afterwards as thsi also helps!
10. If you do find that Damping off is affecting your plants then the best thing to do is to chuck all of the affected trays. ( Not into the compost though - into the bin! ) This may seem harsh but the disease with spread rapidly throughout the greenhouse killing everything literally over night. I have on occasion managed to rescue some seedlings by re potting the unaffected ons into fresh compost in a sterlized container and leaving outside/in isolation just inacase.