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The MGS seed exchange:
Information about propagating from seeds
What to sow now – July / August 2016
What to sow now – autumn 2015
Sowing in autumn
Sowing in September
Sowing in winter
Sowing in summer
Seed workshop at the home of Chantal Guiraud, MGS Seed Coordinator
Seed cleaning made easy - Article from The Alpine Gardener by Vic Aspland, Sept. 2009 (download pdf file)
Seed Germination thread link to MGS Forum
Pricking out seedlings
Thanks to Jamus Stonor for this video.
Music: Blackbird in Gaelic by folk singer Julie Fowlis.
What to sow now – July / August 2016
I’d like to encourage you to sow biennials and perennial plants. July is the best time for biennials but August is not too late, while the mediterranean climate makes it possible for perennials to be sown throughout the autumn.
If the new MGS seed list leaves you uncertain about what to choose, here are a few of my suggestions from the seeds newly listed:
- Acacia farnesiana: Very good germination rate. It is a semi-deciduous shrub for a sunny spot. What makes this shrub of interest is that it is happy in any type of soil, even saline soils. Hardiness zone: 9.
- Ageratina ligustrina: One of the very best plants for attracting bees and butterflies, this is an unusual, evergreen shrub with dark green leaves and long-lasting, large, flattened, white flower heads in late summer. These flowers can last well into late autumn or even until Christmas in a very mild year and are very popular with insects.
- Allium saxatile: Seeds of plants in the garlic family germinate easily but shouldn’t be planted out for a year or two. This particular allium, which resists frost and spreads slowly, is fairly rare. The Allium genus has a triple advantage: its members are decorative, useful and edible. They don’t require summer watering and are the ideal companion plants for peach trees and roses as they contribute to combating peach leaf curl and blackspot.
- Bauhinia yunnanensis: This is a climbing plant from south-west China (Yunnan Province). It has strange two-lobed leaves and mauve-pink orchid-like flowers. With its rapid growth and light foliage, it is of interest for its magnificent flowering in early summer. It is certainly one of the easiest bauhinias to grow. It can withstand occasional frosts of -5°C to -7°C. Indeed, some evidence suggests that this bauhinia might be even hardier and might survive temperatures of about -10°C or even in some cases -12°C. At any rate, it is the hardiest of all the bauhinias.
- Dipsacus sativus: This is a biennial plant, from 50 to 250 cm high, which should be sown in the summer. Differing from the common teasel frequently to be found growing in rubble and ditches, the true weaver’s teasel is a rarer species and was once cultivated to serve the textile industry and workshops, being used to card the wool fibres. Since the 19th century its cultivation has become so rare that the plant is almost at the point of disappearing. Replaced by machines, the poor weaver’s teasel has had difficulty getting used to life in the wild again. If none of us will open our gardens to it, it will very soon be condemned to join the black list of extinct species – and this in spite of its past services to humanity. In France it is called the “cabaret aux oiseaux”, in other words, roughly speaking, the “birds’ bar”, since it sometimes holds up to a litre of rainwater in the leaves that are tightly clasped, two by two, around its stem, thus forming small reservoirs where sparrows come to drink.
- Dolichandra cynanchoides: This vigorous climber, which can reach 8 m or more, has a long flowering period in summer and autumn and may even flower throughout the year in a mild climate. Sow the seed under glass, but be prepared for germination to take two or three months. The plant can easily tolerate temperatures as low as -8°C for short periods.
- Iris lutescens: This iris doesn’t appear in the list for I have only just received the seeds. But if it tempts you, order it fast for iris seeds need to be fresh to germinate well. And they take their time about it, sometimes a whole year. So patience is required.
- Lathyrus odoratus ‘Matucana’ and ‘Cupani’: Autumn is the very best time to sow sweet peas. These two old cultivars are highly scented and violet-purple in colour. ‘Cupani’ seems to tolerate heat better than all other sweet peas.
- Lepechinia hastata: This Salvia relative is heat- and drought-tolerant, evergreen and hardy to -17°C. What more could one ask? It has a late-season flowering with deep magenta-rose blooms.
- Matthiola incana: This is another biennial to be sown from July onwards, with flowers in shades of red, white, mauve and purple. The seeds sprout very quickly, in less than 10 days. I collected them on the Frioul island off Marseille.
- Nolina hibernica: Germination in 3 weeks is problem-free with a success rate of at least 95%. The seeds should be sown on the surface of a freely-draining potting compost and then lightly covered with silicaceous sand. Place the pot in a hermetically sealed plastic bag and put it in a greenhouse with a daytime temperature of 30-35 °C. When the seedlings are well developed, open the plastic bags to give them some air. This plant, which resembles a cordyline, tolerates drought and seems to be hardy to -15°C provided that it has good drainage.
- Rhaphiolepis indica: This is a handsome, hardy evergreen shrub which produces pinkish white flowers in May-June. It prefers slightly acid sandy soil.
- Roldana petasitis: Formerly known as Senecio petasitis, this shrub is worth growing for its large downy leaves with white undersides. It produces yellow flowers in winter.
- Salvia absconditiflora: if you are looking for an attractive groundcover for a sunny site, this is the plant for you. It is a little like Salvia officinalis but with a more carpeting habit and white flowers.
- Salvia barrelieri: This sage, native to North Africa, grows to a height of 1.20 m and produces blue-mauve and white flowers in May-June.
If you have any questions do write to me and I’ll answer as quickly as possible.
I thank all the gardeners who have donated seeds. I wish a good summer to those of you in the Northern Hemisphere and a good winter to those in the Southern Hemisphere
What to sow now – Autumn 2015
Why Not Stay Mediterranean?
Autumn is the time to sow mediterranean plants. I’d like to suggest a few of them, awarded a distinction by the RHS and for the most part easy to cultivate.
First, let’s speak of bulbs – here is a list of some that you can grow from seed:
- Acis nicaensis is easy and germinates well. This plant can be found on the French Riviera and will grow only in alkaline soils.
- Crocus cartwrightianusis an autumn-flowering crocus and believed to be the ancestor of the saffron crocus.
- Crocus goulimyi is native to Greece where it grows in olive groves. It also flowers in autumn.
- Gladiolus communis (syn. Gladiolus byzantinus) is native to northern Africa, western Asia and southern Europe. I like to plant it with the wallflower Erysimum ‘Bowles’s Mauve’.
- Sternbergia lutea (syn. Sternbergia sicula): I like to grow this bulb in association with the grass Hakonechloa macra.
Typically mediterranean plants:
- Argyrocytisus battandieri (syn. Cytisus battandieri): native to Morocco and not too happy in alkaline soil, it has beautiful silky silvery foliage and golden yellow flowers with a pineapple scent.
- Canarina canariensis: a real beauty coming from the Canary Islands. It is a hard-to-find plant with orangey-red flowers. It is not very hardy but can be grown in pots and easily over-wintered in a frost-free greenhouse.
- Centranthus ruber 'Albus': this is a white form of the red valerian that is often seen by roadsides. All its seedlings come true to type, white-flowered too.
- Coronilla valentina subsp. glauca:this plant self-seeds in the garden. The cultivar ‘Citrina’ has paler creamy-yellow flowers but unfortunately seeds from this cultivar do not come true to type and produce flowers whose colour resembles the species. Before sowing, seeds should be placed in boiling water and soaked overnight.
- Cynara cardunculus: a really interesting plant in spite of its tendency to be a bit invasive. It is majestic and edible. It is grown in Provence, Spain, Italy and North Africa, where it makes a good addition to couscous. It has been known in the Mediterranean since time out of mind.
- Dorycnium hirsutum: native to southern Europe all around the Mediterranean Sea. Ideal for poor and stony soils, it produces plentiful nectar, is loved by bees and tolerates salt spray well. The seeds should be given the boiling water treatment, as described above for Coronilla.
- Echinops ritro: native to the southern Mediterranean from Spain to Turkey. In the Languedoc-Roussillon region of France it is colonised by white snails which used to be eaten. This thistle is also useful in flower arrangements.
- Euphorbia myrsinites: this species is present all round the Mediterranean, resists everything including salt spray, and self-seeds without ever becoming too invasive.
- Euphorbia rigida: native to southern Europe, North Africa and the Middle East. Ripe euphorbia fruits have a tendency to explode and project their seeds to a distance. This is their way of colonising a piece of land. If you want to collect the seeds, cover the flowering heads with a stocking or pair of tights in order to gather the seeds more easily.
- Fraxinus ornus: grows wild in the Alpes Maritimes region of France and in Corsica. In the past it was cultivated for its “manna” (hence the name Manna Ash), a yellowish-white acidulated and sweet sap collected by making incisions into the trunks of the trees and known as Apothecaries’ Manna. This was used as a sweetener and was famed for its laxative properties. The tree’s leaves were once used to make a drink called “frênette” and its wood for the handles of tools. Its scented flowers perfume the garden in spring.
- Lunaria annua var. albiflora and var. albiflora ‘AlbaVariegata’: these white-flowered and variegated forms of Honesty are biennials seen in damp areas but as they self-seed well they come back every year. It is worth noting that, unlike Coronilla, seed-grown plants come true to type: seed from variegated plants will give identical variegated offspring.
- Phlomis fruticosa: Olivier Filippi tells us that Jerusalem Sage is easily grown from seed. We can’t reproach such a beautiful plant for the fact that the hairs on its leaves irritate the skin if you touch them.
- Rhodanthemum hosmariense: it’s true that this plant, native to Morocco, is very easily grown from cuttings, but if you don’t have a plant available from which to take cuttings you can order seeds from the MGS seed list and sow them. It is a beautiful rock plant with evergreen grey-green foliage.
- Salvia argentea: this biennial which comes from North Africa is very easy to grow from seed. But if you want to keep your plants going, it is better to cut off the spent flowers before they produce seed.
- Salvia candelabrum: this species lives in the maquis of Andalucia in southern Spain. You’ve got it – it doesn’t need either water or fertiliser. It is also very easy to raise from seed.
- Silene coronaria: the pure white cultivar 'Alba' is very striking and comes true from seed. Like Salvia argentea it is a biennial, and one can thus cut off the spent inflorescences after flowering in order to keep the plant going.
- Spartium junceum: the seeds should be placed in boiling water and left to swell overnight before sowing. The plant’s genus name derives from the Greek ‘spartos’ which means a binding or cord, reminding us how its stems were once used, while its species name refers to the rush since its stems resemble those of rushes.
- Trachelium caeruleum: I haven’t succeeded in growing this species from seed and thus bought one from a nursery, since it is a very interesting plant and easy to grow. In my garden it grows in the shade with practically no water other than that provided from the sky. After its June flowering I cut off its spent flower heads and it flowered again in September. I am waiting impatiently for it to self-seed. Nevertheless, don’t hesitate to sow seeds now, or also in February, under glass as the plant likes warmth.
I can’t resist mentioning three more plants in our seed list which have nothing mediterranean about them but which have qualities worthy of interest:
- Adenium obesum: only specimens grown from seed will form a caudex at the base of the stem. But if you are not interested in this swelling of the stem and are attracted only by its flowers, you can very well grow this plant from cuttings.
- Pachystegia insignis: this is the outsider on my list as it comes from New Zealand, but it can be cultivated in alkaline soils since it grows wild on the sandstone mountains of Marlborough. It is impossible to remain indifferent to the beauty of its downy grey foliage and its large white daisy-type flowers.
- Passiflora capsularis 'Vanilla Cream': this cultivar comes true from seed. I discovered this fact this summer, after noticing many self-seeded progeny around it, one of which was already flowering and had the same creamy-white colour as the mother plant.
Chantal Guiraud October 2015
Sowing in autumn
Chantal Guiraud writes: Some hardy annual flowers can be sown early in the autumn outside and stand the winter season without any protection; they will be stronger and will flower earlier. Generally they are meadow flowers that germinate in autumn and stay as seedlings during winter before flowering in summer. Others, less hardy, may be sown either in situ, covered with a light protection in case of frost, or in pots over-wintered in a garden frame.
Many perennials, most shrubs and trees from temperate or cold regions and some desert plants need a period of cold to break dormancy and encourage them to germinate. Sowing seeds outside in the autumn, usually in pots, allows them to experience the ups and downs of winter temperatures and encourages them to germinate in the spring. If germination occurs in autumn, over-winter the seedlings in a greenhouse or a cold frame. Don’t throw out a seed pot just because nothing seems to have happened, for some plants may take two or three years to germinate.
If you want to have a try, here is a selection from our seed list of plants that can be sown in autumn:
Albizia julibrissin (Greece)
Allium tuberosum (Montpellier-France)
Caesalpinia gilliesii (Greece)
Carissa bispinosa (Blanes-Spain)
Ceratonia siliqua (Greece)
Clematis tangutica (Montpellier-France)
Colutea arborescens (Montpellier-France)
Dianthus barbatus (Great Britain)
Gleditsia triacanthos (Tourettes-sur-Loup-France)
Hyssopus officinalis (Montpellier-France)
Incarvillea arguta (California)
Iris douglasiana (California)
Juniperus phoenicea (Greece)
Lupinus arboreus (California)
Myrtus communis (Greece)
Phlomis russeliana (Tourettes-sur-Loup-France)
Ruta graveolens (Clapiers-France)
Verbena rigida (Greece)
Yucca whipplei (California)
Chantal Guiraud writes: We are already in full summer and, as you will have noticed, everything is slowing down. Plants have stopped flowering; there won’t be much water now to keep them alive so they aren’t going to waste any of it on useless efforts but are waiting for better days. As for the gardener, he or she is going to profit from this summer pause to rest and to think about new plantings. I’d like to invite you to have a look at the new seed list to help you make your choices.
I’ll begin with an extract from Jaqueline Tyrwhitt’s book Making a Garden on a Greek Hillside, which really reflects my own thinking. Don’t get me wrong: I certainly don’t want to discourage you – quite the contrary. Growing plants from seed is a delicate matter but the results are immensely gratifying. As I’ve said many times during workshops, we shouldn’t expect to have a 100% success rate with our sowings. My own average success rate is about 50%. This year it has reached 75% so far and I haven’t had my final word. Indeed, I hope to find the time to sow more seeds in September, and I invite you to do the same.
Tyrwhitt writes: “September is one of the good months for seed sowing, though I have never yet mastered the best rhythm of plant propagation in Greece. Seeds sown in September have to be kept shaded and watered and encouraged to make good roots, yet prevented from getting too leggy and sappy before the cold weather hits them. If they germinate, do not die off at once from the heat, do not damp off from being kept too moist, do not get eaten by ravenous snails after the first rain, do not die off after pricking out for multifarious reasons – including a dislike of our limey, silty soil, which makes a hard surface crust yet dries off very quickly – then they make healthy little plants that hold through the winter, are ready to burst into growth in the spring and have a strong enough root formation to see them through the hot summer.
The other growing seasons are in late November and early December, after the rains have softened the ground and before the really cold weather starts, in late February, after the worst cold is over, and in April for tender plants and late summer-flowering annuals.”
Thus sowing in September should be reserve for mediterranean plants. To be more precise, sowing in late November/early December is appropriate mainly for woody species, either because they require exposure to winter for the process of stratification or because the viability of their seeds is short-lived. What is more, they often have a low germination rate. Nevertheless it’s fun to grow a tree from seed.
To help you make your choice from the seeds on the list offered to MGS members, here is a selection of those that can be sown in September:
- Agrostemma githago
- Anthyllis (hot water treatment)
- Argyrocytisus battandieri (hot water treatment)
- Asphodelus aestivus
- Buddleja officinalis
- Bupleurum fruticosum
- Caesalpinia (hot water treatment)
- Callistemon phoeniceus
- Carthamus dianius
- Cistus (the hybrids don’t come true from seed)
- Colutea arborescens (hot water treatment)
- Coronilla (hot water treatment)
- Dolichandra unguis-cati
- Dorycnium (hot water treatment)
- Ebenus cretica (the seeds should be scarified by rubbing between two sheets of sandpaper. They should then be placed in boiling water and left to swell overnight. The germination rate is fairly low and the seedlings are very sensitive to over-watering.)
- Echinops ritro
- Eryngium variifolium
- Eschscholzia californica
- Fritillaria pluriflora
- Gaura lindheimeri
- Helianthemum canariense
- Hesperaloe parviflora
- Juniperus (To break dormancy, the seeds need to go through a long period of cold; germination takes place from March. Germination rates are low.)
- Kniphofia ritualis
- Linum narbonense
- Medicago (hot water treatment)
- Melianthus major
- Nigella damascena
- Oenothera macrocarpa
- Origanum vulgare
- Retama monosperma (boiling water should be poured on to the seeds and they should then be left overnight to swell. The germination rate is fairly low. It can be increased by scarifying the seeds by grinding before pouring boiling water on them, in order to attack the hard and impenetrable tegument.)
- Satureja thymbra
- Saxifraga stolonifera
- Senecio confusus
- Sesbania punicea (hot water treatment)
- Spartium junceum (hot water treatment)
- Stachys cretica
- Tulbaghia violacea
- Yucca brevifolia
Hot water treatment consists of pouring boiling water over the seeds and then leaving them to swell overnight before sowing them.
You will notice that there are very few bulbous plants among those that I suggest here. This is because I shall write about them in a future article since the subject requires a longer treatment.
Sowing in winter
Chantal Guiraud writes: The time for taking a good look at the MGS seed list has arrived. As every year, I’d be interested to know what seeds you wish for. The seed list contains more than 500 species, of which only 263 got your vote last year – in other words about half of those on offer. Your top ten were:
- Ebenus cretica
- Cosmos sulphureus
- Eschscholzia californica
- Scabiosa cretica
- Coronilla valentina
- Bupleurum fruticosum
- Erigeron karvinskianus
- Crithmum maritimum
- Cistus ladanifer
- Buddleja glomerata
(If you wish to order from this list please check that seeds are still available from the main list)
I must say, I like this selection a lot since most of these are truly mediterranean plants that withstand drought, heat and cold.
At the end of February we can start to sow easy seeds such as Acacia baileyana and A. retinodes and the alliums Allium cristophii, A. flavum and A. tuberosum (the latter being Chinese chives). Asclepias, Banksia, Clematis integrifolia and C. tangutica, Maurandya and Yucca are also easy. Clematis integrifolia is a herbaceous clematis with flowers of a lovely blue. I had brought it from my old garden in Paris and it surprised me by adapting well to the hot, dry climate of Montpellier, where it flowers in shade every year from June to the end of August with very little water.
If you are hesitating and don’t quite know what to choose, I suggest my own favourite plants for spring sowing in March and April:
- Baptisia australis: this is an American plant but is perfectly adapted to drought. Its spikes of blue-mauve flowers make it a good substitute for lupins in alkaline soils.
- Erysimum ‘Bowles’s Mauve’: although this is a cultivar, it comes true from seed and the new young plants resemble their parent in all respects, with mauve flowers over a long period and evergreen grey-green leaves.
- Lunaria annua: You can choose between mauve- and white-flowered honesty, or even with variegated leaves. Honesty also comes true from seed. As it is a biennial it is best to sow it in July, but not in situ as the seedlings will need pricking out before being planted in the garden. It will not flower until its second year, but it will then self-seed in semi-shade beneath trees.
- Nandina domestica: this shrub does very well in the South of France in sun as well as shade, without needing much water. However, the seeds need to be stratified in an unheated greenhouse.
- Nicotiana langsdorfii and N. sylvestris: these tobacco plants should be sown in pans, pricked out into pots and then planted out in the garden in May. The minute seeds should not be covered as they need light in order to germinate.
- Oenothera odorata: this is a really easy plant which flowers in full sun from May to August in subtle shades ranging from vanilla yellow to golden apricot. It is not afraid of drought and self-seeds profusely. Sow it in January-February under glass or on May-July in the open.
- Rudbeckia triloba: also really easy. It is happy in any type of soil and self-seeds widely. It should be sown in April and pricked out in autumn.
- Salvia argentea: this biennial or short-lived perennial should be sown in spring or summer. It is valuable for its magnificent silver-grey foliage.
I’ll end with one of my favourite plants, which has also proved to adapt well to my Mediterranean garden, in spite of the fact that books tell me it requires cool, damp soil. Not true! It grows slowly since I don’t give it much water, but every year from May to June it produces its wonderfully blue flowers while in autumn its foliage turns golden yellow. It is Amsonia tabernaemontana.
Here, then, are a few suggestions to help you decide what to sow. I’d like to take this opportunity to thank all the donors whose generosity has given the MGS seed list its variety and quality. I don’t require large quantities of seed, but it should be collected when ripe and above all it should be cleaned of all debris.
To conclude, don’t get discouraged too quickly. Even famous nurserymen sometimes achieve a germination rate of only 30 to 40% – especially with roses. Divide your sowings into two batches, with half the packet sown in March, for example, and the other half in July. This way you will increase your chances of success. And even if you end up with only a single plant from a whole pan of seeds, it will be all the more precious to you.
Summer Sowing of Seeds
Chantal Guiraud writes: Even if the ideal periods for sowing perennials are spring or early autumn, late August is a good season for beginning to sow. The trick is to learn how the plant would germinate and grow in nature. So try to sow the seed at the same time that it would be sown naturally.
For seeds needing cold stratification, like acanthus, the easiest way is to sow them and put the pots outside for the winter, letting Mother Nature do the work. You just have to make sure the pots don’t dry out. Seed only starts the germination process in the presence of moisture; once this process has started, drying out is fatal to the seed embryo.
Most perennials will need at least two growing seasons to reach flowering size, while some require more time. So, if germination occurs in autumn, over-winter the seedlings in a greenhouse or a cold frame. Don’t throw out a seed pot just because nothing seems to have happened, since some plants take two or three years to germinate.
Here is a list of some perennials to sow in late summer: Alyssum saxatile (syn. Aurinia saxatilis), aster, campanula, catananche, centaurea, gaillardia, gaura, geranium, gerbera, perennial grasses, nepeta, dianthus, papaver, salvia and scabiosa.
Biennals are best started in late spring or summer for transplanting to their permanent homes in late summer or autumn: violas, Cheiranthus cheiri (syn. Erysimum cheiri), Bellis perennis, Hesperis matronalis, etc.
Fast-growing hardy annuals are usually sown in spring but they can be sown in July and will flower later in the season, as for example: Eschscholzia californica, Centaurea cyanus, Delphinium ajacis (syn. Consolida ambigua), Dimorphotheca aurantiaca, Iberis amara, Linaria maroccana, Reseda odorata, Calendula officinalis, Chrysanthemum carinatum, Alyssum maritimum (syn. Lobularia maritima) or Tropaeolum majus.
Seed workshop at the home of Chantal Guiraud,
MGS Seed Coordinator, January 2013
A large group of MGS members came to this workshop to hear Chantal explain how to sow seeds successfully.
Chantal particularly recommends plastic cottage-cheese pots with the drainage basket inside, but there’s a lot of choices: ordinary flower-pots, yoghurt pots, fish or meat containers from supermarkets, individual cell trays (from nurseries or garden-centres), even egg-boxes. You can also get peat pots, but these are best avoided since peat is a diminishing and non-renewable resource. Chantal also showed us how to make our own pots out of newspaper.
Don’t forget to make holes in your containers. The earth should never be too wet. If necessary, sterilise the containers with hot water and bleach. In order to keep the plants moist once they have germinated, you will need a glass plate, plastic bags or cling-film to cover the containers.
There are several options:
Commercial compost: this is poor in nutrients and you will need to prick out the seedlings early.
Garden earth: this will need sterilising in the oven at 200 °C for 2 hours or in the microwave oven for 15 minutes.
Home-made medium: everyone has his or her own recipe. Chantal recommends a mixture of half and half peat and perlite, but it’s possible to increase the amount of perlite to 75%. Other recipes contain sand, garden earth and/or garden compost in various measures. The important thing is to increase drainage so as to avoid stagnation and consequent damping off of the seedlings. NB: Perlite is an amorphousvolcanic glass that has a relatively high water content, typically formed by the hydration of obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently. Vermiculite is a hydrous, silicatemineral that expands greatly when heated. (Wikipedia definitions.) Both perlite and vermiculite are available commercially and online.
Put a little gravel at the bottom of the container and fill it with your mixture to within 3 centimetres of the top. Firm the earth well and water it a very little. Sow the seed, leaving 2 centimetres between each one. Fine seed is more difficult: mix it with sand or with couscous for easier handling, or use a specialised seed-distributor. Cover the seeds with vermiculite to a height equal to that of the seeds. Firm again, then water from below. It helps to put a fungicidal product in the water or, if you prefer, a natural fungicide: powdered charcoal or cinnamon. Usually only one watering is needed before germination. Don’t forget to label your pots, mentioning plant name and date, preferably with an indelible pen.
Some seeds need cold in order to germinate, for example, Mediterranean and North American species. Leave them outside, or in a greenhouse or cold-frame, in the shade. Protect them from rain, slugs/snails and pets. (NB: You could try the following natural slug/snail deterrents: crushed eggshells, coffee grounds or bran. Result not guaranteed.) Some seeds will germinate only after several months or even years - don’t throw pots away simply because nothing comes up immediately. Other seeds need heat: tropical plants need a temperature range of between 24 °C and 28 °C. Keep these seeds in the warmth indoors. There are also seeds which require smoke as well as heat to germinate.
There are 4 key factors in successful germination:
- Heat: between 18 °C and 25 °C according to the different species.
- Water: but not too much of it.
- Ventilation: to prevent seedlings from damping off.
- Light: very important for germination and growth. Without light, the seedlings become leggy. But note that there are seeds which will germinate only in the dark.
Don’t start sowing too early, because the light won’t be adequate. February is the ideal month - the seedlings will be ready for pricking out in March. Don’t be disappointed if all your seeds don’t come up. Even Chantal, the expert, says she has a success-rate of 50%.
Watch your seedlings constantly. When the seed leaves appear, harden the plants off progressively by opening the containers, for an hour at first, but then for increasing lengths of time. Keep turning the pots to stop the seedlings leaning to one side. When two pairs of real leaves have appeared, it’s time to prick out the seedlings. Don’t wait too long, because the roots will end up by getting entangled and this makes pricking out much more difficult. Very important: water the seedlings well the day before pricking out. This makes the task much easier.
Prepare your pots in advance, using a mixture of ⅓ garden earth, ⅓ sand and ⅓ compost. A little fertilizer does no harm. Get the seedlings out with a teaspoon or a dibber.
Make a hole in the earth and gently insert the seedling, holding it by the seed leaves or real leaves. Never hold seedlings by the stem, which is too delicate to handle. Insert the seedlings till the seed leaves are touching the earth. Firm gently. Water, from below. Put the pots in the shade to develop, watering when necessary.
NB: when sowing seed of bulbous plants, leave the seedlings in the same container for at least 2 years, so that the new bulbs can form.
What are the advantages of sowing seed? First, it’s cheaper than buying plants from nurseries. Second, it gives more choice, particularly of species that are not available commercially. Third, it produces plants in large quantities. Fourth, plants raised from seed at home adapt better to garden conditions than those bought at a garden centre or supermarket. And finally, it’s fun!
Chantal also told us how to harvest seeds. On a dry sunny day, cut the stems at ground-level and put them head-down in a large paper bag. Be sure to note down the name of the plant and the year. Leave the stalks to dry for a fortnight or so, in a dry and preferably warm place. Then give the bag a good shake, and the seeds will fall out. Put them in a bowl or soup-plate and blow the chaff away, very carefully.
Some seeds (euphorbia, acanthus, geraniums, erodium, ruellia etc) can be propelled far from the mother plant. To collect these, wrap the seed heads in an old stocking before they become brown, then wait for them to ripen.
In order to send seeds to Chantal, put them in an ordinary envelope, mentioning the botanical name, the year, your own name, and the place where the seeds were harvested. To keep the seeds yourself, put them in a paper bag or envelope (never use plastic because the seed will rot), and keep them in a dry place.
A tip to see whether old seeds are still viable: put them in a bowl of water and the viable seeds will fall to the bottom.
Text by Michèle Bailey. Photographs by Hubert Nivière. Languedoc Branch