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Posted on 8:19 AM by Wanto and filed under
By Bob Patrick
If pots are used bed these down in well dampened peat, as this will prevent the compost drying out quite so quickly, as well as maintaining a moist atmosphere round the leaves of the cuttings, and so minimise flagging. It is important to realise that losses through damping of are usually greater in close, warm stagnant conditions, so glass. The glass should be removed as soon as possible each day.
Ideal propagating temperatures are approximately 70 F to 75 F bottom heat with about 55 to 65 top heat although much lower temperatures will give equally good results. Rooting will be slower however.
The most important factor is evenness of temperature; wide variations between day and night temperature will slow rooting and encourage damping off, so that everything that can be done to minimise this should be done, including damping down thoroughly on warm days, and gentle, light spraying over the cuttings occasionally, plus careful ventilation.
As soon as the pots or boxes are sufficiently damp- do not overwater-they should be allowed to drain for a few minutes and then be placed in the propagating bed or frame.
In some ways this is the finest method of propagation, most nearly approximating to the natural order-the stock will seldom deteriorate if this method is used throughout-and it is very valuable when dealing with varieties which are naturally late in flowering. Varieties such as Mentone, Regina and H.M. Queen Elizabeth in particular are very difficult to flower early except when divided tubers are used. I t must be realised in addition that it is desirable to divide rather than to plant whole tubers. The object is to leave sufficient tuber to keep the plant going until it forms new roots, but no more; an excessive amount of old tuber will only delay the formation of the new roots, and as these are the beginning of the fresh tubers which will ensure the continuance of the plant life it is good to encourage early growth. Another factor is that far too much top growth is produced by the undivided root, and the flowers will probably take second place to leaf growth-obviously not the reason for which dahlias are grown.
The tubers which are to be divided should be put into a cool greenhouse or cold frame in early to mid-March, pressing them gently into the soil in the bed, in such a fashion that only the tubers are covered, not the crown. They can be put into deep boxes if this is preferred, which makes handling so much easier. In any case the soil used should be fairly rich, well drained and yet moisture retentive-again John Jones potting compost is ideal for the purpose. The soil in frames should be lightened with peat and sand with a few handfuls of hoof and horn meal or general fertiliser.
Ideal propagating temperatures are approximately 70 F to 75 F bottom heat with about 55 to 65 top heat although much lower temperatures will give equally good results. Rooting will be slower however.
The most important factor is evenness of temperature; wide variations between day and night temperature will slow rooting and encourage damping off, so that everything that can be done to minimise this should be done, including damping down thoroughly on warm days, and gentle, light spraying over the cuttings occasionally, plus careful ventilation.
As soon as the pots or boxes are sufficiently damp- do not overwater-they should be allowed to drain for a few minutes and then be placed in the propagating bed or frame.
In some ways this is the finest method of propagation, most nearly approximating to the natural order-the stock will seldom deteriorate if this method is used throughout-and it is very valuable when dealing with varieties which are naturally late in flowering. Varieties such as Mentone, Regina and H.M. Queen Elizabeth in particular are very difficult to flower early except when divided tubers are used. I t must be realised in addition that it is desirable to divide rather than to plant whole tubers. The object is to leave sufficient tuber to keep the plant going until it forms new roots, but no more; an excessive amount of old tuber will only delay the formation of the new roots, and as these are the beginning of the fresh tubers which will ensure the continuance of the plant life it is good to encourage early growth. Another factor is that far too much top growth is produced by the undivided root, and the flowers will probably take second place to leaf growth-obviously not the reason for which dahlias are grown.
The tubers which are to be divided should be put into a cool greenhouse or cold frame in early to mid-March, pressing them gently into the soil in the bed, in such a fashion that only the tubers are covered, not the crown. They can be put into deep boxes if this is preferred, which makes handling so much easier. In any case the soil used should be fairly rich, well drained and yet moisture retentive-again John Jones potting compost is ideal for the purpose. The soil in frames should be lightened with peat and sand with a few handfuls of hoof and horn meal or general fertiliser.
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