Have you considered Ilex crenata topiary? It would be less prone to disease/pests than box. Not sure about how much e.g. a spiral would cost versus what you paid but you could have a look searching for “ilex crenata spiral” or “cone” online. Major sellers would be open to replacing / refunding plants, check what they guarantee.
There’s also Euonymus japonicus 'Jean Hugues' and ‘Green Spire’. I have two ‘Green Spire’ balls from my local garden centre — the leaves are larger and somewhat coarser but they do the job, i.e. I can basically ignore them whereas before I had box balls under attack by box caterpillars.
Thanks for the advice. Do you have Ilex crenata and have you had any problems? I have done some research and apparently it can suffer from holy blight! I assume it is less common than box blight.
Is it better to have these topiary's kept in pots (are they less prone to disease if kept in a pot)?
I dug up the two spirals and attach photos so you can see the roots. The yellow looking one is probably dying and the other one looks healthy but I assume will die soon too (the yellow looking one looked like the other one about a month ago).
I don’t have any Ilex crenata, although I’ve always admired the large cloud-pruned specimens like the ones in your link.
Like any plant I suppose it will be susceptible to disease/pests such as holly leaf blight. It’s just that box blight is widespread in the UK and thus it may be more of a possibility (inevitability) if a garden has box that it will get it. The usual route for infection is through the pores on the underside of the box leaves – the box blight spores are carried on moisture and enter the plant through the pores; they can also go directly through the cuticle on top of the leaves. The spores can be spread from garden to garden in the soil on boots, for short distances on animals and insects, and also through water splash. This is an old article but a good read on box blight: https://www.rhs.org.uk/science/pdf/plant-health/box-blight-rampages-onwards.pdf.
Topiary plants should be fine in the ground or in appropriately sized pots, it’s not so much that using pots or planting in the ground will make a difference in preventing disease but rather good care of the plants, monitoring and attention to hygiene can. Some monitoring tips here, probably applies to many topiary plants in general: https://www.bartlett.com/resources/plant-health-care-recommendations-for-japanese-holly.pdf
Other things to do are to ensure plants have the best possible drainage (either in pots or in the ground), to minimise stress from drought or overwatering, and to always use clean garden tools to minimise potential disease spread.
I could be making this up as l go along, but the dead one's roots seem very black/brown (could be a trick of the light),whereas the healthy one seems to have white/light healthy roots. The root balls are a good size. There is disease that affects box roots, but l may be overthinking it. I would replant it (if you haven't already done so) and maybe try a seaweed feed to the roots. Don't be tempted to give it any more than the recommended level on the pack. That's just what l would do though, others may say something different. The joys of gardening
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There’s also Euonymus japonicus 'Jean Hugues' and ‘Green Spire’. I have two ‘Green Spire’ balls from my local garden centre — the leaves are larger and somewhat coarser but they do the job, i.e. I can basically ignore them whereas before I had box balls under attack by box caterpillars.
Is it better to have these topiary's kept in pots (are they less prone to disease if kept in a pot)?
I quite like the look of something like this if it is less likely to die than my buxus:
https://www.paramountplants.co.uk/large-image/ilexcreponponbon/ilex-crenata-pon-pon-bonsai.html
I dug up the two spirals and attach photos so you can see the roots. The yellow looking one is probably dying and the other one looks healthy but I assume will die soon too (the yellow looking one looked like the other one about a month ago).
Like any plant I suppose it will be susceptible to disease/pests such as holly leaf blight. It’s just that box blight is widespread in the UK and thus it may be more of a possibility (inevitability) if a garden has box that it will get it. The usual route for infection is through the pores on the underside of the box leaves – the box blight spores are carried on moisture and enter the plant through the pores; they can also go directly through the cuticle on top of the leaves. The spores can be spread from garden to garden in the soil on boots, for short distances on animals and insects, and also through water splash. This is an old article but a good read on box blight: https://www.rhs.org.uk/science/pdf/plant-health/box-blight-rampages-onwards.pdf.
plants in general: https://www.bartlett.com/resources/plant-health-care-recommendations-for-japanese-holly.pdf
Other things to do are to ensure plants have the best possible drainage (either in pots or in the ground), to minimise stress from drought or overwatering, and to always use clean garden tools to minimise potential disease spread.
There is disease that affects box roots, but l may be overthinking it.
I would replant it (if you haven't already done so) and maybe try a seaweed feed to the roots. Don't be tempted to give it any more than the recommended level on the pack. That's just what l would do though, others may say something different. The joys of gardening