Himalayan poppies grow in some of the most inhospitable parts of the world – which is why they thrive in Yorkshire winters

AT this time of the year if you take a walk along the lower section of the sandstone rock garden and streamside at Harlow Carr you will find the impressive blue poppy, Meconopsis ‘Lingholm’, a very popular seasonal highlight for many of our visitors.

These bright, blousy blue poppies first appear as a rather insignificant looking plant, emerging from beneath the mulch during March. The garden staff take great care not to damage these plants and weed with caution in and around them as they can be rather brittle and snap easily. At this early stage of their development they look rather unassuming and could be mistaken for young stinging nettles in appearance.

Meconopsis was first introduced into the UK by the famous plant hunter Frank Kingdom-Ward many years ago. Most of the plants currently occupying the garden at RHS Garden Harlow Carr originated from plants used during the blue poppy trial that took place a few years ago under the watchful eye of some passionate alpine enthusiasts and nurserymen from the RHS trials department, the Alpine Society and the Meconopsis Group. The trial was run over a period of three years and assessed the individual cultivars for their flower quality, longevity of flowering, growth rate and form. Himalayan poppies - or Meconopsis as they are called botanically - grow in their native state in some of the most inhospitable parts of the world on scree in a cool aspect at high altitude. Harlow Carr was chosen as an ideal site for the trial as the conditions here are relatively cool and moist with an acidic soil. Of course the garden at Harlow Carr cannot match the altitude of the Himalaya, but at 500 feet above sea level, the plants will certainly have endured the rigours of many a typical winter in Yorkshire, which can at times be rather testing.

Young plants will not produce the elegant blue flowers for a few years; if flowers do occur they should be removed so the plant can develop strong shoots at the base. Early on in the year they produce delicate leaves that are mid-green in colour with bright coppery hairs under the leaf. It is thought that these hairs help the plants to regulate the loss of moisture through the leaves via transpiration and thus protect the leaves from the drying winds.

Meconopsis ‘Lingholm’, occasionally referred to as Meconopsis x Sheldonii, can be seen growing along the streamside, peat terrace and woodland edges at Harlow Carr and thrives in dappled light. It will not tolerate long periods of bright light and high temperatures. The plants we raise each year from seed for the garden can also be propagated by division in the spring, but more normally during the autumn or early winter. It is wise to collect seed each year and have a supply of nursery plants as cover for any losses as these plants can perish in very wet conditions. The seed can be collected from the seed head from late August and should be placed in a brown paper bag until the seed naturally explodes out of the seed head; seed not sown should be placed in a container in a fridge. The larger seed is the more viable seed and should be sown into modular units using an ericaceous compost that is both free draining and moisture retentive. The seed should be topped dressed with alpine grit and placed in a cold frame or cold glasshouse. Germination usually takes between three to four weeks in the autumn. Any seed that has not germinated will usually come through by the following spring. Once the plants are large enough to handle they should be carefully removed from each module and potted on into a 9cm pot in a free-draining compost made up from a combination of loam based compost with grit, leaf mould and a little perlite.

These plants are relatively pest free, but early in the year, slug damage may be a problem so use barriers such as grit and dry mulches to deter any infestation.