How to pot up Crocus bulbs

Select one pot to work on at a time then remove labels and keep together in tray (orange tags can be returned to store).  Carefully tip out contents and put corms to one side (some are very tiny and might be in the gravel layer.  Then double check old compost for more corms and discard this into ‘used compost’ wheelbarrow.  At the base of the pot you will retrieve a square of gauze and this is reusable in a new pot.

To clean the corms gently rub off any loose material, there is no need to peel back layers that don’t want to come away easily.  Be aware of not snapping delicate tips and then place clean corms into tray containing labels.  Try to group corms loosely to give an idea of the pot size required.  You can use the same pot if the size is appropriate, just make sure you brush it out first, or retrieve a larger pot from the pot store.

Make sure the pot has no cracks or chips and then insert the green gauze at base to cover drainage hole.  Fill the pot halfway with fresh potting mix, if all corms are very tiny (5mm or less) then fill the pot to 2/3rds.  Then cover the potting mix with a 5mm layer of sharp sand.  This is to help water drain away from the corm, and as an indicator of depth when repotting next year.  It also helps to hold small corms upright when back filling.

Place corns upright (not always that clear) into sand leaving only a small space between corms.  Try to mix the sixes of corm to have an even spread of flowers.  Re-insert labels at this stage so if any corms fall over you can prop them back up.  If there isn’t a ‘secret’ label please write one including the accession number and full name.  Cut down to size so it sits just below the rim of the pot.

Back fill with fresh potting mix almost to the top of the pot and give a gentle wiggle to level surface.  Tap pot to settle mix into air pockets around corms and fill more if required.  Top dress the pot with washed grit.  The best method is to slightly over fill and then gently wiggle the pot to allow it to settle and the excess to fall off.  Then place pot on trolley, clean down and start on the next pot.

By Sarah Carlton Alpine and Woodland Supervisor

Cardiocrinum giganteum or The Giant Himalayan Lily


The majestic Himalayan lily is  certainly a garden show stopper!  It is the largest species of any lily found growing in the Himalayas, China and Myanmar. White trumpet flowers stand tall on a stem reaching about three metres in height.  

The  scented trumpet flowers  intensify at the end of the day and are pollinated by moths.  The giant Himalayan lily grows  best in woodland areas away from strong sunlight and dislikes drying out during the summer months. This plant can be a challenge for horticulturists to grow as it can take up to seven years before it flowers!  After flowering the plant will die but it will produce accessory bulbs. 

These bulblets can be propagated to produce new plants themselves taking 3 – 5 years to flower. The seed is best sown as soon as it is ripe in in a cold frame during the autumn. The plant has delayed epigeal germination which means it can often take two years to germinate which typically occurs in spring.

The seed is sown fresh at St Andrews Botanic Garden as this helps get best results using a seedling potting mix and is then lightly covered with vermiculite. Seedlings are then grown on in pots in a shaded position in a cold frame or our shade tunnel for 3-4 years before planting out in their permanent position in the garden. Each year you can see the plants growing in the temperate glasshouse where they typically flower in May,  or June outdoors in the woodland.  

Despite the lengthy germination and time taken to  flower it is definitely worth the wait and here at St Andrews Botanic Garden our horticultural staff ensure we have a continued succession putting on a magnificent display for our visitors.

By Kirsty Wilson Glasshouses Supervisor