There are three methods of propagating gladiolus – the less common seed and tuber propagation and the most common tuber propagation. Tubers are divided into large (3,2 cm in diameter and larger), medium (3,1 to 2,5 cm) and small (up to 1,5 cm). Tubers smaller than 1,5 cm are no longer considered as tubers but as corms.
Tubers are divided into generations according to their age: tubers sown in the spring and grown in the autumn are first generation, those grown the following year are second generation and so on. Generations 1 to 3 are more suitable for propagation and have particularly beautiful flowers. Tubers older than 4 years are no longer suitable for propagation.
Propagation of tubers and corms
In order to multiply tubers more quickly, they are usually divided into several (three or more) parts. This way, tubers in fractions 1-2 are propagated much faster. The tubers are divided one at a time, one to three days before planting. All the parts must have root suckers and buds, as all the parts produce plants, but not all of them flower or flower later than usual. The cutting shall be done with a sharp knife which shall be disinfected after each cutting. It is also very important to make the cuts with crushed charcoal mixed with TMTD powder or sulphur. Another trick for faster multiplication of corms is to plant them with the bottom up.
To produce larger tubers, you need to break the inflorescences to prevent them from flowering. When planting, the top sprout has to be broken off, followed by the dormant buds, which eventually result in plants of 2 groups.
Cardoons propagated by corms start to degenerate over a longer period of time, so it is necessary to propagate them from corms.
After 2,5 to 4 months, it is possible to sow tubers. They are divided into the following categories: smaller – up to 0,9 cm in diameter – and larger – between 0,9 and 1,5 cm in diameter. The latter germinate better. If the tubers are stored in the right conditions, they will remain germinated for a very long time, possibly even several years. Suitable conditions are a low temperature (about 2 to 3 degrees) and sufficient humidity (80-85%).
Suitable substrates for sowing
As regards the most suitable sowing substrates for boxes and inspectors, this would be litter peat (pH 5,5 to 6,5) chalked up at a rate of five to eight kilograms per metre. At the same time, mineral fertilisers are added to the peat by repeatedly digging it up: ammonium nitrate 400g/m3, superphosphate 1300g/m3, potassium nitrate 1000g/m3 and magnesium sulphate 300g/m3. This is followed by the addition of micro-fertilisers; in 1m3 of peat, 80g of iron sulphate (FeSO4), 5g of manganese sulphate (MnSO4), 25g of copper sulphate (CuSO4), 4g of zinc sulphate (ZnSO4), 4g of boric acid and 1g of molybdate ammonium. If the peat is friable, the micro-fertilisers can be added dry, but it is better to dissolve them in water and mix them into the peat, digging several times.
When to plant cardoons
In the field, once the soil has begun to warm up and the soil has warmed up, the corms can be sown. New varieties should be sown in March. The tubers are sown in the ground in picking boxes, with about 150 pieces in each box at a depth of one or a couple of centimetres. The boxes are initially kept at a moderate temperature (about 10-12 degrees Celsius) and then left at a temperature about 10 degrees Celsius higher once they have rooted and the seedlings have appeared. The best environment is preferably a greenhouse, but other well-ventilated, bright places may also be suitable. After frost, the seedlings are planted in the soil by simply removing the bottom of the box.
Be aware that if you want to grow first or second-fruits tubers in one season, then the growing period should be extended. Here are some tips to help you extend the growing season and produce larger tubers. The growing season can be extended, for example, by sowing the tubers in heated transplants. In this case they are placed more densely than in boxes. Sowing should be done when the outside temperature rises above freezing. The inserts should be covered with straw at night and ventilated during the day. The frames should be removed when it is completely warm outside. The plants should be covered with polythene sheeting when the autumn frosts start.
It is very important that plants that flower early age faster, so it is not advisable to aim for flowering the same year. On the contrary, if flowers appear in autumn, they should be picked before they open. Doing so will result in much better growth of your gymnosperms.