How to Train Ceanothus to Grow Vertically

Known for its flush of blue blooms in summer, ceanothus, also known as California Lilac, is a really popular flowering shrub. It’s one of our favorite evergreens for a small garden space and is a great plant for pollinators.

As beautiful as they are, ceanothus can become very bushy, so they might not always come to mind as a great option for a small garden.

They tend to have a pretty vigorous growing habit, and within one season, you could expect to see over 1-2 feet of growth.

Unlike slow-growing dwarf conifers, ceanothus will need annual pruning and training to keep it in check in a small garden space.

However, with a little maintenance each year, you can easily train a ceanothus to grow upright against a wall or fence. This will allow you to enjoy its beautifully fragrant display of flowers without it taking over your garden.

Choosing a Ceanothus variety

Different ceanothus varieties can have different growing habits. Some will have a naturally more upright shape. And others will form more of a low-growing bush.

Starting out with a naturally more upright variety could help you keep on top of pruning. Some great upright ceanothus varieties include:

• Lemon and Lime
• Lemon Ice
• Puget Blue
• Concha
• Mystery Blue
• Wisley Blue
• Eldorado

If you’ve already got a different variety planted in the ground, don’t worry. With training, almost any ceanothus can be trained to grow vertically.

For example, creeping forms of ceanothus can be trained to grow up a wall too. Varieties like ‘Creeping Blue Blossom’ and ‘Mahala Mat’.

Positioning your ceanothus

Ideally, you need to plant your ceanothus about a foot away from the wall or fence behind. This should give enough space for you to prune behind the plant, but also allow enough space for the foliage and flowers to flourish.

Plant your ceanothus in the sunniest and most sheltered spot in your small garden for maximum blooms and full foliage. They don’t do well in windy or water-logged conditions, so keep this in mind when planting.

You can grow ceanothus in containers, however, make sure that you have a good-sized pot with plenty of drainage holes.

Training a ceanothus to grow vertically 

Whether you’re training a ceanothus to grow vertically against a fence or wall. The trick is to encourage the central stem to remain upright, and keep lateral stems short or flush against the wall/fence (depending on how wide you’d like your ceanothus to be).

Training ceanothus against a fence

If you’ve positioned it near a fence, you may be able to tie some string around the trunk and main stems and then also loop the string around a supporting fence pole or panel. 

When tying the stems in, make the tension slightly loose. If it’s too tight it could damage the bark as the ceanothus stems will naturally thicken throughout the year.

Check the ties every 6 months. Make sure they’re not too tight, haven’t come undone, and are holding the central trunk in the correct position.

Training ceanothus against a wall

When training ceanothus against a wall, it may be easier to place a trellis, pole, or something to tie strings to against the wall. It needs to be a solid support that won’t fall over and one that can support the tension of several strings holding the stems.

As the woody stem becomes thicker and stronger, you will eventually be able to remove any retaining supports or ties. Then pruning will be key to keeping your ceanothus at a manageable size.

Pruning your vertical ceanothus

For evergreen ceanothus, it’s best to wait until after flowering to start pruning. Usually July/August for spring/early summer flowering varieties and spring for late summer/autumn flowering varieties.

Deciduous ceanothus varieties will need a different pruning schedule, so double-check which type you have.

Pruning newly planted or young ceanothus

Pruning the growing tip early on encourages lateral shoots lower down. This should help your ceanothus to look fuller, instead of the foliage being concentrated at the top.

The key is removing stems that are growing in unwanted positions. Stems that are growing too far back into the wall or fence, or stems growing out into your garden should be pruned back to help keep the shape as upright and narrow as you need.

On evergreen ceanothus, flowers grow on last year’s growth, so don’t prune back stems all the way. Simply remove dead wood and unwanted stems (growing out into the garden) and lightly prune the remaining stems. Pruning up to a third or a half of the stem is usually the maximum recommended amount.

Pruning old, mature, or established ceanothus

For a more established evergreen ceanothus, it depends on the size of the plant and how much you’d ideally like to prune.

The general pruning rule is to only remove up to a third to a half of a stem/branch. Any more, and a mature ceanothus may not respond well. If this is the case, the best action may be to replace the shrub with a younger ceanothus that is will be easier to train.

Writing notes or setting up a calendar reminder is a great way to keep on top of when your ceanothus may need pruning. For that incredible flush of delicate purple and blue flowers, it really is worth it!