The age and season of planting is important for all container grown wildflowers. Ideally well grown plants, which are rooted through the volume of compost within the container, (but not rootbound) should be supplied at a time of year when they are likely to establish and grow away with the minimum of demands of maintenance. For NPS wildflowers age and season should be considered.
The plant, grown from seed, must have sufficient time in the container to germinate and establish a well rooted and vigorous plant. To do this, it is more important to specify that the plant has a reasonable length of a growing season in the container than a statutory number of months. For example, seed germinated in the spring can be ready for supply in early summer. On the other hand, seed germinated in autumn requires a period of the following growing season (spring) to ensure vigorous plants.
Ideally wildflower plants should have one growing season in container before supply, or sufficient months of a growing season to ensure good growth and rooting.
There are exceptions to this rule. Some wildflowers establish and grow very rapidly from seed and within a matter of a few weeks can fill the container. Details of these species need to be obtained from specialist growers before specification.
Container grown wildflowers need to be planted at the correct time to give the best chance of successful establishment. Ideally planting should take place during calm, dry weather when the soil can be worked, between late September and early April, when rains are likely to aid establishment. If planting takes place during the summer months, then it must be looked after carefully to ensure establishment. These plants, smaller than most container grown bedding plants, will grow and establish vigorously if planted at the right time but will very rapidly die on dry, windy sites in early summer.