Sowing in Depth of Winter

Now that the days are starting to get longer, our thoughts turn to summer and growing plants.   Whilst it is possible and indeed in some cases desirable to sow early, this is not the case for the majority of seeds unless we take additional steps.

Warmth

For any seed to grow, one of the triggers in warmer weather.  So sowing in winter requires the use of bottom heat.  A propagator (with or without thermostat) or a heat mat is ideal.  Over a radiator is not a suitable environment unless its all you have got.  Most radiators sit under windows (most of mine do) and the temperature above the radiator can be too much when it is on and nearer the glass far too cold.  The 'goldilocks zone' can be as small as a few cm wide in the middle of that area, hence why we cannot recommend this.

Light

The increasing days will provide this for your seeds, especially those that are sown on the surface and need light to germinate.  Avoid South facing windows at all costs, if this is all you have, set the trays and pots back a metre or so, this way you diffuse the light a bit and avoiding the thermal effects of full sun.

Another way with light, is artificial lights.  Whether this is a standlight or a hanging light, it must be full spectrum or a specific growlight designed for the purpose.  LED versions of these lights may sit just a few centimetres above the seeds, as their main output is light. Sodium or other metal halide lights should be sat well above the tray as most of their output is heat.

We use the LED types on pullies sat above the seed trays so we can adjust the height. Inside a mylar grow tent, little additional heat is required apart from a heat mat to warm the soil.  Most of our out of season testing is done this way so that we can check the seeds first before the main growing season.

Our entire set up uses around 300 watts for 12 hours a day and 80 watts for the other 12 hours.  With this we can have up to 24 full sized seed trays, although we rarely fill it if we intend to grow the seedlings on for our own use.

Growing On

Don't forget about the space you will need for growing on and where you intend to do this.  The temperatures here can and indeed should be lower than those used for germination.  The amount of light required will increase too, but never be tempted to place them where they get full sun.  Even cacti will scorch and die if subjected to full sun as seedlings.

We sometimes use the grow tent to bring the seedlings on fast.  This works well for the stronger growing perennial types, especially Agaves, Aloes and relatives.  We also grow chillis (when we have space) under this set up, being able to keep 4 to 8 plants and bring them into fruit as early as June.

Grow Tent - A New Experiment

Grow Tent - A New Experiment

Finally took the plunge and invested in a grow tent for seed testing.  Big enough to provide for 115 x 7 cm pots, it should allow me to test pretty much all of my smaller seeds.

So far it has all of my seeds that require very warm conditions, with the bottom heat and the ceramic heater providing air temps of a stable 26 Deg C and soil temperature a few degrees above that.

At this point, I have had Stapelias showing in 24 hours from sowing, Pachypodiums from 48 hours, Astrophytums in 72 hours and my own super hot chilli peppers germinating inside 4 days.

The kit so far includes

1. 120 x 60 x 150 cm Grow Tent
2. 2 x 50 cm square heat mats
3. Minature Fan Heater (400 watts) with thermostatic control
4. 600 LED full spectrum grow light
5. Inline vent fan (not currently being used as I need a close atmosphere)
6. Remote temperature and humidity sensor so I can check temps without leaving the house

As I get results from this, I will be able to modify any care sheets that I have for the more tropical species we stock.

Growing South African Bulbous Plants from Seed

Growing South African Bulbous Plants from Seed

South African bulbs and tubers can be broadly split into two categories, the summer growers and the winter growers.  Check carefully in the list at the foot of the page to determine which category your purchase(s) fall into and then follow the relevant instructions below.

Should you find that now is not a good time to sow your seeds, store then in the fridge (inside the Mail-Lite bag I used to ship them to you), where they will happily stay until it is a better time to of year to sow them.

Winter Flowering Bulbs

Sowing time – Late September to early March

Surface sow the seeds in pots of free draining compost and lightly cover them with fine grit or vermiculite.  Water well, just once, and then seal the pot in a plastic bag.  Germination should occur within 7 – 28 days or so, some species may take longer.  Temperatures for germination to occur should be around 15 Deg C during the day and lower at night (but not below 7 Deg C), so a cool window sill or greenhouse is ideal.  Once germinated grow the seedlings on in cool conditions as too high a temperature may cause drying out or trigger the premature onset of dormancy.  Seeds sown towards the end of the season (early March) should not be allowed to go dormant in their first season and provided with shade so as to allow the bulbs to fatten up properly.

Except as mentioned above, these bulbs have a pronounced dormancy period in the height of summer and the pots should be allowed to dry out (to rest the bulbs) from mid-July to October.  To bring them back into growth, start to water them gently and ensure they are growing in a cool, frost free location.  The bulbs can stay in their original pots for a few seasons until they appear crowded.  1st flowering depends on the species and is mentioned in the description.

Summer Flowering Bulbs

Sowing time – Late February to July

Surface sow the seeds in pots of free draining compost and lightly cover them with fine grit or vermiculite.  Water well, just once, and then seal the pot in a plastic bag.  Germination should occur within 7 – 28 days or so, some species may take longer.  Grow on in either a greenhouse or a cold frame and try to keep them going for as long as possible in their first season (perhaps as late as mid-October) so as to speed up the onset of the first flowers.  Doing this can shave a year of the stated time for the first flowering to occur.

Most of these bulbs have a pronounced winter dormancy period and they can be lifted and stored frost (and rodent) free, where there is doubts as to their hardiness.  Otherwise they can be mulched with straw or a thick layer of peat to give added protection.  Re-plant lifted bulbs or tubers the following spring for growing in that season.

General Guidelines

All bulbs can be grown in pots as well as in the open ground (depending on the location).  They should be fed so as to ensure the growth of the bulb rather than to green up the leaves.  To this end use a fertiliser that is high in phosphates, rather than one that contains too much nitrogen.  The soil mix should reflect that these plants store water in their bulbs and tubers and should not be subjected to prolonged waterlogged periods.  Use a free draining mixture wherever possible, in the same way as you would if growing cacti or succulents.

A rule of thumb guide for the species follows, but please check each variety as to whether winter or summer flowering is suggested...

Summer Flowering: Agapanthus, Albuca, Aristea, Babania, Crocosima, Dierama, Dietes, Eucomis, Freesia (some), Galtonia,  Gladiolus (some), Gloriosa, Hesperantha, Kniphofia, Littonia, Nerine, Sparaxis, Tulbaghia, Watsonia (some), Zantedeschia.

Winter Flowering: Bulbinella, Chasmanthe, Daubenya, Ferraria, Freesia (some), Gladiolus (some), Ixia, Lachenalia, Lapeirousia Massonia, Melasphaerula, Moraea, Ornithogalum, Spiloxene, Tritonia, Tritoniopsis, Velthemia , Wachendorfia, Watsonia (most), Whiteheadia

Generic Instructions

This is a generic set of instructions for those seeds which do not require specific handling. Most seeds I sell will grow given the following treatment.

Pretreatments.

Larger seeds (over 2mm) may be soaked in hand hot water overnight to speed up germination. Very hard coated seeds may be soaked in a dilute solution of Saltpetre made up as per the directions given under the pretreatment leaflet.

Smaller seeds need no pretreatment.

Sowing (Traditional Method)

Sow in a moist (not wet - a test is to squeeze a handful and if more than a few drops of water come out, then it is too wet), good quality seed compost, barely covering the seed in the case of large seeds and with small seeds sow on the surface and, if able, press them in (but no more). Place in a propagator or seal in a plastic bag and keep at 18 – 28 Deg C (Air Temp), soil temps need to be warmer by about 10 Deg C or so. Germination for most types should be fairly rapid (3 – 4 weeks or so), although it can take some time for all of the seeds to germinate. The following types can take up to 8 weeks to germinate – Aralia, Cussonia,Fatsia & Ficus.   Some types, with very hard seeds, may take several months to germinate - these include Gardenia, Rothmannia and Tabernaemontana.  

 

Above all else, unless you are certain that the seeds are not going to show (mould, algae or thick moss on the surface of the pot), persevere. Seeds have inbuilt survival mechanisms that will prevent germination unless conditions are right and may wait months before doing anything if sown at the wrong time. With modern advances in lighting, heating etc for plant raising, seeds may be sown at any time with these aids BUT there is no getting round the time of year - some seeds have a 'clock' and if it is the wrong time of year they just will not come up until it is the right time of year...  Just keep the soil from drying out completely and keep going.

Sowing (Alternative Method)

This method uses no soil in the initial stages, but it should be cautioned that the seedlings will need transferring to soil very soon after germination.  To do this with small seeds, simply place a paper kitchen roll sheet (folded as necessary) into a plastic container which has a lid. Soak the kitchen roll until it is wet, but no excess water is in the bottom of the tray.  An easy way to do this is to add too much water, let the excess collect in the bottom of the pot and then pour it away. Sow the seeds onto the moist paper and then seal the lid. Place at germination temperatures and then just wait until the seeds sprout.  If condensation forms on the lid, tap it to let it fall onto the seeds.  This method does require scrupulous hygiene as if fungal infections get hold, you will lose the batch and you cannot really use fungicide.  When the seeds sprout, you should get them in soil as soon as possible, still in controlled conditions and then allow them to root and grow on. Huge batches of seeds can be sown this way in small spaces, we have stacked containers one on top of each other on the propagators using this method with those seeds needing most heat on the bottom.  This is especially suitable for seeds that get soaked before sowing, as well as very small seeds that cannot be soaked in case you lose them.

Growing on.

Grow on, maintaining a close atmosphere opening the bag or propagator every few days to freshen the air. Once 2 or 3 true leaves appear the seedlings can be gently transplanted in order to grow on. Use any good quality houseplant compost for the potting on – garden soil should never be used as it is very variable in quality and may contain many weed seeds and pests.

Continue to pot on as required, some vigorous species may need 3 – 6 re-pottings per year, whereas slower growers may need potting on every other year. Let your plants tell you when they need to be potted on (they will slow down in growth or just ‘look’ unhappy)

If you have any questions please contact me at robert.boatman@gmail.com or bob_b@bsquared.ndonet.com and I will be happy to help out with any specific tips I am aware of or I can share my experiences.