Before heading out to begin the May bonsai jobs, we take a quick look out of the window to see what the weather brings for us.

Capable of very nice days and equally some late frosts, May teeters on the fence between spring and summer. Regardless of the weather, many of us are glad to get outside, be it to work on bonsai or in the garden.

So, this month’s bonsai jobs bring us the tantalising start of enjoying the results of our hard work. Flowers, fertiliser and foraging for pests take centre stage this month.

Look out for

Trees flowering this month to brighten up your day include Crab Apples and Cherry that continues to flower from last month.

Make the most of these moments and grab your phone or camera to take impromptu photos. They are great for reference and can use used on your own printed calendar for next year.

Fertiliser Regime

You should be well underway with your application of fertiliser. If you are using a water additive, then ensure that you are following your plan.

With slow release fertilisers, you should make sure that they are still in place and that they do no need replacing. Using fertiliser baskets will help to stop the fertiliser from blowing off or being removed by birds.

Ensure that you have sufficient fertiliser to see you through and purchase more where stocks are low.

Peaches and nectarines

If you have peach or nectarine trees, then now is the time to give them a spray with fungicide. This will help to prevent the unsightly and health damaging leaf curl.

It is also wise the thin out the developing fruit to reduce the stress on the bonsai.


Non coniferous evergreen trees start their growth this month and its time to give Azalea and Camellia bonsai a trim. Pruning the growing tips is the best way to maintain their shape as the risk of frost is reduced. If you are looking to reduce the size of the tree then cutting into the previous years growth will achieve this.

Pot on seedlings

Any seeds that you gathered and sowed late last year should now be large enough to handle. If they are, then now is a good time for potting on into individual pots for development. Take care to handle the seedling by a leaf, trim the tap root and pot then up in a good quality, free draining soil.


The warmer weather will bring out more pests. Still top of the list this month are the aphids, greenfly, blackfly, woolly aphid and sawfly. If you spot signs of these pests then take immediate action to stop them in their tracks. Also on the prowl are the adult Vine Weevils, looking to lay their eggs.

If you grow hosta plants as accent plantings, then slugs and snails are on the prowl. Garlic solution could be the perfect answer to keep them at bay.

As always, we urge you to look at organic methods to tackle pests. These methods include hand picking them off or spraying with a washing up liquid solution.

You could consider encouraging or buying natural predators to assist in combating pests, such as ladybirds and their larvae. This way you help to maintain a natural balance and will not risk killing the beneficial insects.

Upcoming events this month

Final thoughts

It’s good to the Chelsea Flower Show back in its usual time this month. Whether you usually attend or watch the superb coverage on BBC, there is always plenty of inspiration. I always like to see what fabulous garden Kazuyuki Ishihara has designed to inspires us on his annual trip to Chelsea with a slice of Japanese garden.

Finally, don’t forget to air your greenhouse and cold-frames during the day and close the doors at night.