The Vervain can't stand temperatures below zero; they should be grown in cold green houses or at least in a place where they are sheltered by the wind; when every risk of late freezings has gone by we can place them outside or remove the protections. These plants have an annual development, therefore when it becomes cold they deteriorate, and get completely eradicated.The Vervain should be grown in a bright place, with direct sunlight.
The Vervain have a one or two year development cycle. The Vervain is medium in size and 20 cm in height; in the spring, summer, autumn, winter it assumes a red colouring. These plants aren't evergreens, which means they lose their leaves some months during the year. These plants grow covering the whole land at their disposal.
Annual plants have a quite vigorous development and need, during the spring, a continuous fertilization; when placing them let’s add some humus or mature manure or some slow release granular fertilizer to the ground. During the spring months we suggest mixing some fertilizer for flowering plants to the irrigating water every 20-30 days.
Water rarely, about once every 1-2 weeks with 2-3 glasses of water , keeping the soil dry for a few days before watering again; when wetting we suggest avoiding surpluses, however to wet the soil deep down. As the cold weather arrives, in autumn, usually waterings is interrupted because these plants can't bear harsh temperatures.
Generally during this time of year we suggest a pre-emptive treatment with wide range insecticide and with a systemic fungicide, to prevent the attack from part of the aphids and the development of fungus diseases, often favoured by a mild and damp climate.
We advise locating these annual plants in a dissolved soil, with an elevated drainage.
When wanted we can grow these plants in a vase. The indications given in this article are related to a medium size plant.