Thompson & Morgan Facebook Q&A Session 5th April 2013 - Your horticultural questions answered.

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Name: Pearse Carty

Question: Hi Sue, Just to introduce myself, I'm one of your company trialists, having great fun with Mal's fantastic selection of this year's new plants! I'm pretty sure I got my Xerophyllum Tenax seeds from yourselves. For whatever reason I don't seem to be able to propagate them. I failed with two sets last year as well! Yet, I'm having no problems with a huge variety of others. I'm also having difficulty with your Wild Iris (Dietes Grandiflora) again this year. As far as I can tell I'm following the correct advice. Do you please have any ideas? I haven't put the Xerophyllum in my fridge which is suggested if I have any problems because rather stupidly I sowed both types in the same tray (at the time I was conscious that I'd need every tray available for the many hundreds I was planning), and because they both had the same temperature range of 15 to 21C. So, would it be wise to put the lot in my fridge without risking killing the Iris? I sowed both on 22.01.13. Thank you, and best wishes, Pearse Carty.

Answer: Hi Pearse, once sown, wild Iris (Dietes grandiflora) is best kept in a cool, well-lit spot outdoors or in an unheated room. Try covering the seed with a 5mm layer of compost or grit to help keep the seeds cool. It’s best not to provide artificial heat as this may prevent germination. We have checked and we don’t have Xerophyllum in our product range so you must have come by them from somewhere else. However we can confirm it does need at least 12-16 weeks of cold stratification for germination. Wild irises naturally germinate in spring after a good chilling or freezing period so placing them in the fridge along with the Xerophyllum will actually help with this process. Simply put the sown tray of seeds in a polythene bag in the bottom of the fridge for 12-16 weeks. After this chilling time, move the sown tray to the warmth again and germination should commence but may be erratic. They are both definitely seeds that require a lot of patience! I hope this helps Pearse, best of luck with your garden this year.

Name: Fiona Harrison

Question: I bought 3 outdoor jasmines from you early last summer, 2012. I wanted information on if I should prune them or not. They have grown about 70cms approx. Last year's leaves have gone brown and I notice that 2 tiny new shoots are coming from each joint up the stem. Is this normal?

Answer: Hi Fiona, I’m not sure if you’re referring to Trachelospermum (Star Jasmine) or Jasminum officinale/Jasminum x stephanense but both need similar care. Trachelospermum are evergreen climbers whereas Jasminum officinale/stephanense are deciduous or sometimes semi-evergreen climbers. They’re not fully hardy plants and may suffer some damage in severe winters where temperatures regularly drop below -5°C (23°F). The leaves turn brown due to cold and frosty weather but as you’ve seen they soon bounce back in the spring! Neither plant needs much pruning at all - only to keep them within the available space. Simply prune back to a pair of healthy buds. Once your climbers are mature it’s a good idea to prune out a selection of the oldest or most overcrowded shoots right back to the base of the plant. This allows light and air to circulate, discouraging disease and encouraging healthy new growth and flowering. Prune Trachelospermum in early spring and Jasminum after flowering in late summer or early autumn. I hope this helps, best of luck.