Growing Alpines From Seed: Part 2

Table of Contents and IntroductionAfrican Violets: the Doyen of House PlantsAgapanthusAlstroemeriasAmerican SagebrushesAmerican WildflowersAndean Nymph - a pink mimulusAquilegias (Columbines)AuriculasAustralian AnnualsBellis Perennis (Daisies)Black-Eyed SusanBlue African LiliesBreeding DelphiniumsBreeding Fuchsias: Part 1: From SeedBreeding Fuchsias: Part 2: HybridisationBromeliads from SeedButterflies in Soy SauceCacti RaisingCampanulasChilean Bell FlowerChilly Treatment for Peruvian LiliesCollecting SeedConserving Annuals and BiennialsCosmosCucumbersCycads: Living FossilsCyclamen for IndoorsDahlias from SeedDamping OffErythroniumsF1 Hybrid - What Is it?F2 and Open Pollinated VarietiesFrom Obscurity to the Height of FashionGentiansGeraniumsGermination to Pricking OutGolden Impatiens - The StoryGrowing Alpines From Seed: Part 1Growing Alpines From Seed: Part 2Growing Bananas From SeedGrowing Cyclamen From SeedGrowing Eucalyptus From SeedGrowing Ferns from SporesGrowing Foxgloves From SeedGrowing Fritillarias From SeedGrowing From Seed: From Packet to SoilGrowing Hardy Ferns from SporesGrowing Hardy Geraniums From SeedGrowing Lewisias From SeedGrowing Magnolias From SeedGrowing Meconopsis From SeedGrowing Proteas and Related Genera from SeedHandling Small SeedsHardy Annuals: Part 1Hardy Annuals: Part 2Hardy CyclamenHardy SpurgesHelleboresIncreasing your Violas and ViolettasKeeping Records of Seed SowingLettuce - the Vital Part of any SaladLord Anson's PeaMagnolias - the Root of the ProblemMimulus from Seed to Seed in Sixty DaysNew Guinea ImpatiensOld-fashioned Sweet PeasOnions with EverythingPansies are not Difficult to Grow from SeedParsleyPerennials for American GardensPetuniasPhygelius - their cultivation and propagationPinks: Evocation of the PastPlants That Flower OncePrickly but NicePropagatorsRadishesRaising PalmsRaising PrimulasSalad Leaves - a lot to be desiredShow Stoppers Twice OverSowing SeedsSowing in Open GroundSowing to Feed our FriendsSturt's Desert PeaSweet Peas - Autumn SownSweet Peas - Sowing and GerminatingTall and HandsomeTechniques with Tiny SeedTexas BluebellThe Effect of Light on Germination and SeedlingsThe Nervous PeaThe Scarlet Welsh PoppyThe Search for the Yellow Sweet PeaToad LiliesTomatoesTreasure Hunt for TasteUnderstanding Latin NamesUnique Poppy (Mother of Pearl)Viability of VegetablesWeaning SeedlingsWill the Real Mimosa Please Stand Up

Jack Elliott concludes his short general survey of growing alpines from seed.

In the first part of this article I discussed some of the theoretical considerations and details of the materials used in growing alpines from seed. Here I will deal with the practicalities of seed sowing and the subsequent treatment of seedlings, considering first techniques suitable for the general run of alpines, followed by any special treatment required by certain more specialised groups.

Sowing

The time of sowing and the various composts available have already been discussed. The depth at which the seed is sown is important and depends on the size of the seed involved, bearing in mind that the seed should be just covered with a sprinkling of compost through a sieve, but should then be covered with a generous layer of grit. In general this should be a quarter to half an inch deep to ensure that the seed will not be disturbed by watering or by heavy rain subsequently. The finest seed may need special treatment (see below).

Every gardener has his own technique of sowing the seed on the carefully flattened surface of the firmed compost. The most popular method seems to be straight from the packet, cutting off its top or a corner, and then tapping gently with the forefinger to get an even sprinkling of the seed. This becomes easy with practice but can be nerve-racking with rare seed and a variety of different packets! The classic alternative is to empty some or all of the seed into one palm, and to take pinches of it between finger and thumb and sprinkle it around the surface. This is probably safer with very small quantities.

'Sow thinly' - you will always be told, and it is good general advice, but if you know the germination is likely to be erratic you can safely sow thickly to get an adequate number of seedlings. Your ideal is to produce a pan of seedlings which are only just touching each other when they are a suitable size for pricking out. Conversely, if you have sown too thickly you will have to prick out more quickly, to avoid the risk of damping off or of damaging the roots of the seedlings.

After sowing and covering the seed the pots must be labelled, and thoroughness at this stage may save problems later. The difficulties of labelling apply here as much as elsewhere, particularly the lack of permanence. Most growers use white plastic labels. Ordinary pencil lasts well on them but takes longer to write and is less easy to read than ink in the first place. Unless you can find a permanent ink it will probably be necessary to re-write the labels occasionally and it is important not to leave this too long. The label should carry the date of sowing, the name of the plant, collector's number if applicable and the source - often the most interesting and important item! If the number of seeds is small (say under five) it is worth giving an indication on the label. This is important when you find a pot with only one or two germinated seedlings.

It is very helpful to keep the same information in a book, perhaps with more detail about the source and details of subsequent treatment. If germination records are added you will have information which will be invaluable in the future, especially in the case of newly-collected or little known plants.

The newly-sown plants should be placed in a shady place open to all weather, unless they are known to be tender, in which case a cold house is advisable. They must be watered thoroughly with a can with a fine rose or a suitable hose attachment producing small droplets. They must be kept shaded and watered until germination, even if this takes several years. Ideally alpine seed pans should be kept for at least three years. They sometimes germinate after this time and in discarding them after a couple of years you will be losing some potentially viable seed. If suitable space is at a premium, a shady corner of the garden can often be found where the older pans can be put for a year or two, with an occasional watering during prolonged dry spells. One major problem in retaining pans for a long time is the development of moss or liverwort. A grit surfacing will usually prevent this for a year or two.

Seedling Treatment

When seedlings appear the pans should be transferred to a frame or cold house so that they receive more light, with some shading in hot weather. When to prick out is the next vital question, the two most frequently offered bits of advice being 'when the seedlings are large enough to handle' or 'when they have developed two true leaves'. Both suggestions are sensible and frequently both amount to the same advice, suitable for the average pan of seedlings which has been sown at the correct density and has germinated well and reasonably early in the season. If the seedlings are overcrowded, maybe because you have underestimated their viability, they must be pricked out quickly, even if they only have their cotyledons. This is easy if they are large - in fact there is no objection to doing it at this stage routinely, but difficult if they are very small. It is still worth trying, even if in practice it means pricking out little clusters of seedlings. There will be less risk of damping off than if they are left together in the seed pan, and a few alpines like Gentians and Primula do better in clumps.

A different problem arises when only two seedlings appear in a pan. Assuming there were a reasonable number of seeds sown - hence the importance of the label - you are faced with a decision whether to rescue the seedlings or leave well alone in the hope that more will germinate before the original plants have become too large and filled the pan with roots. In practice, unless your one or two plants are sufficient for your needs, it may be possible to have the best of both worlds. If the seedlings are near the side of the pan they can be dug out at the cotyledon stage, before the roots are too long, with a dibber or a kitchen fork, leaving most of the compost behind and resurfacing it with grit. If the seedlings are in the centre or if they have well-developed roots it may be easier to tap out the pot full of compost and remove the top half inch from around the seedlings with a flat instrument, replacing it on top of a fresh pot full of seed compost- and making good the surfacing.

Most germination takes place before the end of June and it is usually better to leave any pans germinating later until early the following spring, unless they are sufficiently vigorous to be dealt with before the middle of August. Pricking out seedlings in the autumn is better avoided as winter losses seem then to be heavy, even in a greenhouse. It is surprising how well even pot-bound and tangled seedlings will recover when pricked out in March. If in doubt you can prick out half the seedlings, filling the hole with fresh compost, and leave the remainder for later treatment if the first batch is unsuccessful.

The seedlings should be separated carefully and planted singly, one to a pot, unless they are extremely small, in which case they can be planted an inch apart in a pan or tray until they are large enough to pot singly. For most plants small plastic pots are suitable for pricking out into, although many alpine experts prefer clay pots even at this stage (see High Alpines below). The composts recommended for seed sowing can be used, with John Innes Base to the strength of J.I. No 1 substituted for the superphosphate in the 'home-made' compost, or John Innes No. 1 compost with the addition of a third of its bulk of Perlite or grit.

The small seedlings with short roots can be planted by filling a pot to the brim with compost, making a hole with a finger, and inserting the seedlings while firming the compost around it. If you have judged this right there will be ample room for a layer of coarse grit around its neck, with the surface still below the pot rim. If the seedlings have well-developed roots, rather than squashing them into a narrow hole, fill the pot a third full with compost, firm it and then, holding the seedling at the right level with the end of the roots in the compost with one hand, pour compost round it and firm it, then add the grit surfacing.

After planting the seedlings should be watered and kept in a frame or cold house. Even the sun lovers will need some shading in the early stages and care must be taken Subsequent Treatment

Alpines vary enormously in their rate of growth but the time will come when their roots reach the sides of their pot and come out of the drainage hole. They are then large enough to be planted in the garden or re-potted into a more nourishing compost, for instance John Innes No. 2 or its equivalent, with a third of its bulk at least of extra grit. It is vital even in the open garden to make sure that the newly-planted alpines get adequate water during dry spells until they are established.

Special Groups