Growing Seeds -some notes on how to get successful results. Excellent reference: theseedsite
You will find that everyone who grows seeds, from amateur to professional, has a preferred method to get seeds started. Always consider the options, as many seeds require individual treatment to get the best results. In many cases you are reproducing the environmental effects that the seeds would experience in their natural habitats, and where they normally germinate. In others you are speeding up the process artificially. Seeds bought from suppliers have usually been specially treated in some way to help the breaking of dormancy and give you reliable results. This could be temperature cycling or chemical processing. The seed companies also seal their seeds in controlled conditions, and might include hermetic or dry nitrogen enclosures. Add to this the fact that most seeds have a viability of far less than 100%, some as low as 10% (i.e. the proportion of seeds that can be expected to germinate at all!). Germination rates vary widely, so it is not uncommon for seeds to show up one or two at a time over a long period. Be patient!
I personally have not found covered propagating frames easy to use. You need to protect from direct sunlight, but at the same time keep the soil damp and ventilate with fresh air. They are useful of course to protect the trays from domestic pets and birds. A cool, bright greenhouse is ideal but I realise that this is a luxury for most people. A cold frame is a good alternative.
Self seeding often produces great results. Let the seed heads ripen, and allow (or help) the seeds to drop on to the soil. Don't do anything, and let the Winter break the dormancy naturally. Great for Calendula, Escholtzia, Ageratum, Verbena bonariensis, Cineraria, Myosotis and many others. Drawbacks: they grow everywhere! Open pollination produces variable results.
If you want to take a chance with a quick start, here's how:
Always follow instructions on packets. Many annual bedding plants will start easily. You will usually find this applies to the frequently grown Species and old garden types as you would expect.
1. Make sure that all trays and containers are clean. Wash off, or ideally sterilise with Jeye's fluid.
2. Use a proprietary sterilised medium, such as John Innes seed compost (was No1). This does not contain nitrogen, only phosphates for root growth.
3. Sow seeds at a depth no more than 2x their diameter. Note that some seeds must be surface- sown as they need daylight to germinate.
4. Water gently (ideally by standing the pot or tray in water until the medium is damp). Use Cheshunt Compound (copper sulphate and ammonium carbonate) in the water to inhibit damping off (a fungal disease that kills the seedlings after they have emerged). Never soak the medium, or water too often.
5. Keep tray at around 15-20 deg Celsius, in bright but not direct sunlight. Do not allow to dry out. Ventilate.
KICK START THE GERMINATION - seed treatments
1. Find out if your seeds need a cold period before they will germinate (either from the supplier or from a good reference book). This is typical of many perennial plants, for example Allium, Acer, Meconopsis, Picea and other conifers etc. Many of these can be sown in the Autumn and over-wintered in a cold frame or under cover outside. Alternatively they can be kept for a period of time in the bottom of the fridge (not freezer!). Times may vary between 4 weeks to 6 months. The process is called 'cold stratification'. The usual method is to mix the seed with damp sand then leave in the fridge in a polythene bag for the recommended period. Some seeds benefit from a complicated regime of cool/warm cycling, but most of these are probably too specialised for the home gardener. Professional growers sometimes use chemicals to break dormancy.
2. Some large or hard seeds benefit from 'scarification'. This is basically roughening or chipping the hard surface of the seed so that moisture can penetrate more easily. Gently rub the surface of the seed with sand paper, or put them into a bag with dry sand and shake them for a few minutes. The large seeds can be carefully chipped using a sharp knife. Some gardeners like to soak the seeds for a short time in tepid water. Typical seeds are large hard tree seeds, sweet peas, peas, some beans, etc. I have not found these methods very helpful, but as you know garden lore is difficult to prove or disprove! Don't be afraid to experiment.
3. A very interesting seed treatment is that used to start seeds native to areas where forest fires and brush fires occur. Seeds are available for plants that grow in the national park areas of South Africa. (eg proteas, reed grasses). These will only germinate after a fire has swept across the surface. It has been found that it's not the heat but the chemicals in the smoke that start the germination. It is now possible to obtain 'artificial' smoke tablets. These are dissolved in water and use to soak the seeds before planting. They even smell of smoke!
Germination times can vary from days to years! See the charts at http://theseedsite.co.uk for useful data.
FACTORS AFFECTING GERMINATION
Light........Temperature Range (maximum AND minimum)....... Humidity........Time.......Viability.......Depth of planting......Pre-conditioning
All must be correct to ensure germination. Check the recommendations for specific seed, and note that too hot OR too cold will inhibit growth.
Most garden soils, especially on modern estates, are not very good for sowing seeds (although of course many seeds do well by direct sowing in mature ground and allotments). My soil on a modern estate is very stoney and clay-like, wet lumps in winter and rock hard in Summer, really hopeless for seed sowing. The amazing thing is that the self-sown seeds still seem to grow well-especially the ephemeral (= several generations in a season) weeds. To get good results you will probably need some decent seed compost, usually worth the cost as seeds are not cheap and you don't want to waste them. The Important thing is to note that SEEDS DO NOT NEED FERTILISER in the soil. The seed is it's own food store, and you do not need to feed them until after transplanting. Indeed, if you do, they will often put on fast 'leggy' growth then collapse!
There are dozens of proprietary soil and soil-less mixtures for seeds, and you will get good results with most. Some people advocate the use of vermiculite mixed with the compost (to keep the air in the soil and help with moisture retention), others sprinkle the surface with sand or perlite.
Remember that the compost must 'breath' i.e. it must not become compacted and air must be allowed to migrate through the soil. The roots can only work properly if air is present. I have found that a mixture of washed sharp sand and grow bag contents (either organic or peat based) makes a good seed compost. It is weed and pest free, has good consistency, and does not dry out quickly. And it's a cheap way of doing it! The grow bag does contain a minimum fertiliser additive, but not too much as explained above. This is a soil-less compost as it does not contain loam.
If you find it more convenient to buy ready made composts, John Innes seed compost is a fine mixture of loam, sand and peat with a small amount of added phosphate. Loam is a composite of small particles of sand, silt, clays and organic materials together, with many trace elements like iron, calcium, zinc, molibdenum, sulphur and others. This medium has been sterilised to eliminate weed seeds and insects. Or, of course, you can use one of the other proprietary seed composts that use organic, composted chipped bark and other materials. I have found that products such as coir (coconut husk) based are either expensive or not suitable. There is no substitution for experimentation, but don't experiment with expensive seeds!
PLANTING TIME Remember......self- seeding plants choose their own planting times!
HA Hardy Annual..........................Early Spring/ late Winter February/March or Autumn. Will tolerate frosts when grown
HHA Half Hardy Annual.................Spring April/May Killed by frost. Will tolerate down to 1deg C.
HB Hardy Biennial......................July for flowering the following year.
HP Hardy Perennial....................Feb/March/April some types will flower first year. August/September for following year flowering.
HHP Half Hardy Perennial.............As for Perennial. Won't stand frost, so must be protected in Winter
T Tender..................................Sow indoors or warm greenhouse in late Spring. Sub tropical and tropical plants minimum temperature 5 deg C.
Do this a soon as you can. Although the plantlets are very small, they generally recover from the shock faster than bigger plants. The two cotyledons open first (the two usually roundish light green bits that open from the seed). They are not true leaves. The first real leaves come next, so plant out after they have formed completely. Hold the plant by the leaves, not the stem. If the stem is damaged it will not re-grow properly, but plants can recover from leaf damage. Use a fine compost like John Innes potting compost, light and airy. Do not soak, use Cheshunt or other damping off inhibitor for the first watering only. With monocots (grasses, agapanthus, eremurus, kniphofia, iris etc.) wait until two complete leaves have formed.