Problem Solver - Why did strawberry tree die suddenly?

Q What was the cause of my strawberry tree’s sudden death?

A Very simply, your strawberry tree (Arbutus unedo) failed to establish a good root system. It should have easily doubled its root spread over 18 months, but it appears to have made very few, if any, new roots. Gardeners often contribute to establishment failure by poor planting technique. The main failure is through not thoroughly teasing out the rootball prior to planting. The all-too-often-heard advice of not disturbing roots is just nonsense. Container-grown plants are well-grown at nurseries, but invariably root bound. It’s essential to thoroughly tease out the rootball to get these roots growing out into the surrounding soil, which is very different to the potting compost they’re grown in. You can’t usually do that with your fingers. I use a patio weeding tool, but a sharpened piece of bamboo, or similar, will do the job. Long, circling roots should be uncurled and pruned off at the side of the rootball.  Make the planting hole no deeper than the depth of the rootball, but three times as wide, as roots tend to grow sideways, not down.  Finally, don’t add organic matter to the planting hole as this tends to discourage rooting out into the surrounding soil. On very poor sandy soils you might incorporate some as part of the backfill (the soil dug from the hole).  Secure the tree trunk a third of the way up a tree stake, inserted diagonally at 45 degrees. This will ensure the new roots aren’t broken if the tree’s subject to high winds.  Planting too deep is the other major contributing factor. Again, the advice to plant at the depth the tree was in the pot is misguided as a lot of nursery stock is mechanically potted and is too deep to start with. This is the case with your tree, which was potted at least 5cm (2in), if not 7.5cm (3in), too deep. The tree has produced additional adventitious roots from the buried trunk to try to compensate but without success. With poor root growth, the tree has eventually come to a halt and died.

A Very simply, your strawberry tree (Arbutus unedo) failed to establish a good root system. It should have easily doubled its root spread over 18 months, but it appears to have made very few, if any, new roots. Gardeners often contribute to establishment failure by poor planting technique. The main failure is through not thoroughly teasing out the rootball prior to planting. The all-too-often-heard advice of not disturbing roots is just nonsense.

Container-grown plants are well-grown at nurseries, but invariably root bound. It’s essential to thoroughly tease out the rootball to get these roots growing out into the surrounding soil, which is very different to the potting compost they’re grown in. You can’t usually do that with your fingers. I use a patio weeding tool, but a sharpened piece of bamboo, or similar, will do the job. Long, circling roots should be uncurled and pruned off at the side of the rootball. 

Make the planting hole no deeper than the depth of the rootball, but three times as wide, as roots tend to grow sideways, not down. 

Finally, don’t add organic matter to the planting hole as this tends to discourage rooting out into the surrounding soil. On very poor sandy soils you might incorporate some as part of the backfill (the soil dug from the hole). 

Secure the tree trunk a third of the way up a tree stake, inserted diagonally at 45 degrees. This will ensure the new roots aren’t broken if the tree’s subject to high winds. 

Planting too deep is the other major contributing factor. Again, the advice to plant at the depth the tree was in the pot is misguided as a lot of nursery stock is mechanically potted and is too deep to start with. This is the case with your tree, which was potted at least 5cm (2in), if not 7.5cm (3in), too deep. The tree has produced additional adventitious roots from the buried trunk to try to compensate but without success. With poor root growth, the tree has eventually come to a halt and died.

Propagate primulas from seed

This is a fun little project to attempt now your Primula veris and P. vulgaris have largely finished flowering. They will seed themselves, but you might just wish to experiment with your own man-made propagation to see how well you do. Just be aware they can be a little tricky sometimes.  The seed is very fine and doesn’t need burying under compost – just leave it on the surface of moist compost, covered with a fine layer of grit, which gives light protection but room for seedlings to emerge from it. Once sown keep your seed tray at around 15C (59F) for germination, but be patient! It’ll take a while – up to six or so weeks – for possible germination. If it doesn’t happen in that time, give your seed tray a period of cold stratification – a few weeks in the fridge – and then bring out to the warmth again.  Once seedlings have grown and can be easily pricked out, grow them on in small pots before planting out in autumn. 

This is a fun little project to attempt now your Primula veris and P. vulgaris have largely finished flowering. They will seed themselves, but you might just wish to experiment with your own man-made propagation to see how well you do. Just be aware they can be a little tricky sometimes. 

The seed is very fine and doesn’t need burying under compost – just leave it on the surface of moist compost, covered with a fine layer of grit, which gives light protection but room for seedlings to emerge from it. Once sown keep your seed tray at around 15C (59F) for germination, but be patient! It’ll take a while – up to six or so weeks – for possible germination. If it doesn’t happen in that time, give your seed tray a period of cold stratification – a few weeks in the fridge – and then bring out to the warmth again. 

Once seedlings have grown and can be easily pricked out, grow them on in small pots before planting out in autumn. 

Make a bee hotel

Solitary bees are very useful to us gardeners and are likely to frequent the bee hotels you can make for the garden. They're fantastic pollinators of a wide range of plants, particularly fruit trees and bushes in spring, as being able to fly they can reach these plants in cool, sometimes rainy weather, to pollinate them just when they need it.  They like to make nests in little tunnels, so any old strong bamboo canes with sizeable enough holes, about 50mm wide or more, can be fashioned into a nice little nesting site for them. It's wonderful to see them being used, and you'll be surprised at how many bees use it if positioned in the right spot. Mason and leafcutter bees will use bits of plant leaf to create cigar-like tubes as nests in the holes. Mason bees also like to use teasel and sunflower stems to nest, so these will work too.  For a more secure 'hotel' look, enclose all your stems or canes in a frontless wooden box and hang on the wall. 

Solitary bees are very useful to us gardeners and are likely to frequent the bee hotels you can make for the garden. They're fantastic pollinators of a wide range of plants, particularly fruit trees and bushes in spring, as being able to fly they can reach these plants in cool, sometimes rainy weather, to pollinate them just when they need it. 

They like to make nests in little tunnels, so any old strong bamboo canes with sizeable enough holes, about 50mm wide or more, can be fashioned into a nice little nesting site for them. It's wonderful to see them being used, and you'll be surprised at how many bees use it if positioned in the right spot. Mason and leafcutter bees will use bits of plant leaf to create cigar-like tubes as nests in the holes. Mason bees also like to use teasel and sunflower stems to nest, so these will work too. 

For a more secure 'hotel' look, enclose all your stems or canes in a frontless wooden box and hang on the wall.