The more sour the better for these plants!
This month I thought I would chat about all things ericaceous meaning those plants that love acidic conditions spurred on by a visit to the National Botanic Gardens at Kilmacurragh, in Wicklow. This is a fantastic garden not far from Wicklow town with the most spectacular collection of Rhododendrons and unusual conifers all thriving in the acidic soil the garden county is famed for.
The thing about these plants is, they prefer it when the pH is at the lower end of the scale as they can access much needed nutrients which are otherwise unavailable in alkaline conditions. What is pH though? It is a measure of the concentration of hydrogen ions in a solution and this is measured on a scale known as the pH scale. The very lowest or most acidic conditions are akin to battery acid so naturally enough very little plant or otherwise will grow in such harsh environs. Adversely, at the opposite end of the scale, where we find the most alkaline conditions, these are similiar to bleach so are equally as inhospitable. That is why the vast majority of plants will happily grow in the middle ground of pH 7 and if you look at your water bottle you will see that most drinking water is around this mark so we thrive in this part of the pool too.
There are always exceptions and this is where the ericaceous plants (those from the Ericaceae family) differ from those that prefer a neutral pH. Acid loving plants prefer it when the pH is in and around 5.5 which includes such beauties as heathers, Camellias, Rhododendron and Azaleas. You can also add Acer, Pieris and blueberries to the club. Most of these plants are native to elevated habitats along mountainsides and in bogs and fens. They not only love those acidic conditions but are well accustomed to the wet that comes with the territory. Acid lovers by nature had to adapt to these harsh environments as many nutrients which are water soluble were washed away with high levels of precipitation. As a result they evolved to thrive in the acidic substrate and continue to produce the fabulous blooms they do each spring.
One of the most familiar ericaceous plants is of course the common heather Erica carnea and one which provides us with much needed colour early on in the year. A common sight in the garden centres, Erica is one of the few acid lovers that can be quite forgiving when the pH is closer to alkaline unlike its cousin Calluna vulgaris or Daboecia cantabrica which will only grow in acid soil, hence their preferred home in acidic boggy conditions or on the local mountains.
Although the selection of plants for these conditions are limited there are still some super additions you can add to your garden like the native strawberry tree Arbutus unedo which is found growing around the southwest of the country and bares those striking bell-shaped flowers common to the plants of that family. If it is conifers that you are interested in and are lucky enough to have the space to accommodate them you are in luck as many also prefer acid soils. If you already have conifers and find your garden is littered with pine needles don't despair as these make the best ericaceous compost once broken down after a couple of years.
If your soil has a neutral pH, you can still indulge in a little ericaceous love by simply growing them on in pots and using ericaceous compost which has a lower pH than multi-purpose. As is the case with all container grown plants, they rely on you to provide moisture, nutrition and adequate light and space. It is therefore imperative that you feed them on a regular basis during the growing season to ensure the conditions remain suitable and for acid loving plants it must be a suitably acidic feed. If you are not sure what pH your soil has you can readily pick up a home kit that will give you a general idea of what you are working with.
Do make sure to get out and visit the gardens in and around Wicklow for their amazing displays right now. The plants won’t be in flower for much longer so the sooner you visit the better!
As always, Happy Gardening Folks!
P.s. I still have places on my April Weekend Course starting next Saturday April 6th so do get in touch if you would like to sign up!