Wednesday 30 August 2017

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

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