Underplanting is when you plant complimentary plants around the base, or underneath the main plant. For instance planting groundcover around the base of a low tree to fill in the area. As an example, Roses are often underplanted with spring bulbs or low flowering annuals.
Underplanting helps prevent bare areas under larger plants and trees, and helps create visual interest and better structure to your garden. It creates for a more harmonious feel to the garden, and can be used to draw the eye around the garden vertically, but also allow the opportunity to create areas of contrasting colour and visual interest. It’s a classic gardening technique that can be used for impressive results, and once you know what plant to plant with another it will take your gardening to the next level.
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What is underplanting?
Want to make a landscape look great? Then you’re going to need more than just grass and tall trees – it’s pure misery forcing woodland plants to grow out in prairie settings, especially in the open.
Example of underplanting flowing shrubs and annuals under trees
A common practice with a lot of gardens and landscapers is to plant individual trees on stretches of lawn. But, even though it’s common, it’s not always the right way to go about it – it stunts these communal plants for life.
Sure, it looks good – we are used to it. But in reality, woodland flowers and groundcovers, understory shade plants, and trees grow well together and look great while at it. Not only does the combination of plants look terrific, especially if planted for all seasons, but it also makes for an easier place to rake or blow fallen tree leaves when it’s autumn.
So, it’s natural to underplant trees and large shrubs with other things. Plus, it’s easy to care for and maintain.
“Underplant?! What’s that?”. Well, underplanting is an easy and nifty style of gardening that helps magnify the impact of the plants being put in.
Picture this – you grow plants that you are attracted to. You combine them so they look good. You place them in the ground, step two steps back, and think, “that’s a gorgeous plant.” Underplanting takes it to a whole different level.
Underplanting takes those plants you love and makes them sing. But that’s not all! It adds a little spice to the tune and brings an instrumental accompaniment. Basically, underplanting turns your gorgeous plant into a work of art – it turns “that’s a gorgeous plant” into “that’s a gorgeous garden.”
The next question is, how do you know what to plant with other plants?
How to Decide What to Plant Next to Other Plants?
The characteristics you want to look for in plants that work well for underplanting include having a bit of spread or frothiness. These plants cover the soil and base around the plants you’re pairing them with, while adding contrasting and layering texture.
While you’re trying to know how to work out what plant goes well with another plant, you should note that not all the low-growing plants that do great at the front of flower beds are necessarily good for underplanting.
For instance, Dwarf Irises, which are spiky, don’t offer adequate horizontal coverage for underplanting. Another example is dense or overly aggressive plants like Snow-in-Summer or Phlox Subulata may choke out or compete with the plants they are meant to complement.
Shrubs, annuals, and perennials are good for underplanting. However, it depends on the size of the plants you wish to underplant, as well as the season you are hoping to get results.
How do I underplant and where do I start?
First, you need proper soil preparation if you want to get your understory plants started on the right foot. This is especially necessary for shallow-rooted and under older trees where the soil is dry and poor. Plus, you need to set out smaller plants with higher chances of springing up quickly.
Additionally, with mature trees, you shouldn’t pile a lot of fresh dirt over their roots – this can suffocate the shallow but important feeder roots. You can haul in around two or three inches of new soil. Even at that, you should work it into the existing soil – dig gently between the older main roots near the trunks. Plus, you want to avoid piling soil up on tree trunks as this causes decay.
Once you are done planting, use a thick layer of easily compostable and natural mulch like chopped tree bark or leaves. Why? Well, this keeps things looking neat and helps the roots of tender new plants stay moist a bit longer. As the roots naturally compost, it feeds the worms around that area which then burrow deep down between roots – this makes natural paths for water, air, and the roots to grow even deeper.
One last thing – you shouldn’t turn the area into a swamp by watering daily. Instead, for the first summer or two, water deeply and as frequently as required. Also, wait till the second year before pushing new plants with fertiliser – you want to get established in the roots first before you load them up with top growth.
What Can Be Underplanted?
You know those plants with vertical stems springing out of the earth without something to embellish the base of their stems? Deciduous shrubs like Weigela and spireas, Shrub Dogwoods, many spiky perennials, and even tulips and other taller spring bulbs – they all do this. And, they all need that “finishing touch.”
Those are the kind of plants that look great underplanted.
Plants like foxgloves with flowery spikes emerging from their low-lying bed of silvery leaves don’t need underplanting. So, when you plan on hitting the nurseries or feel like your garden needs a bit more spice to banish the blahs, take a close look at what’s blooming and get it a close friend.
There are many options to choose from, but here are a few you can start with:
Underplanting with Hostas
Hosta sieboldiana var. elegans
Hostas are a great plant for underplanting taller shrubs and trees. Hostas are low growing plants that come in all shapes and sizes, and commonly prefer a more sheltered and moist environment, so perfect for underplanting many taller shrubs and trees where they will naturally get shade and protection.
Hostas can also be underplanted with spring bulbs themselves, so you get a three layered effect at different times of the year. There are many different leaf colours and textures available from hostas, from larger leaves that create form and structure, to smaller groundcover style leaves that can fill in the empty spaces. Hostas are an excellent choice, and for me mark the start of excitement as the ground starts to warm up in the spring.
First the bulbs will spring up at the start of the year, followed by the hostas later on in spring (assuming not munched by the slugs!)
Underplanting with Ferns
Polystichum setiferum ‘Herrenhausen’ – Soft Sheild Fern
Ferns can be used for underplanting many taller shrubs and trees. I have all types of ferns underplanted in part shade throughout my garden.
I love to plant smaller ferns around the base of my larger 6ft tree ferns to compliment the shapes and textures. They also love the same conditions so perfectly suited here for underplanting. Personally, I like to see larger swathes of the same plants, rather than single plants in isolation. It’s far more impressive seeing a huge bank of the same colours and textures, allowing your eyes to spend more time to take in the planting scheme as a whole, rather than flitting between isolated plants.
Underplanting with Heucheras
Heuchera Palace Purple for underplanting
Heucheras are another often colourful low growing plant that can be used to under plant all kinds of other plants and shrubs. I have Heuchera underplanted around my trachycarpus palm tree, and also underneath an area of Cannas. Heucheras have the benefit to being pretty hardy in the UK, so you can just leave them in the ground and allow them to do their own thing. There are so many types available, and you’ll find them in pretty much every garden centre and nursery around the country. They have pretty little flower spikes towards the end of the summer which also add a bit of interest. The deep purple heucharas are by far my favourite.
Other underplanting ideas
Under planting with Crocosmia Lucifer
Easy to grow and gorgeous late summer when the red flower spikes arch over the border, these plants can be used for great effect as underplanting larger shrubs and trees, especially when the ground is a little dry or thin from the trees. They cope with pretty much everything as long as they are given a good start, I have them dotted around under my larger cherry trees and prunus trees, as the surface roots get in the way of most other plants, so here adding in a few lucifer bulbs (as well as anything else you might like such as daffodils) you can just place them in any gaps between tree roots.
Under planting with Persicaria microcephala ‘Red Dragon
Persicaria is another easy to grow plant that I use to underplant all kinds of other plants in my garden. What I like about Persicaria is the deep purple colours, which you can use to create a foil or contrast against other plants. I have persicaria underplanting bamboo, palms and even banana plants. Anywhere where you have too much green in the border, a small clump of deep purple persicaria will add a nice contrast.
Under planting with Low flowering Myosotis
This is a classic underplanting that offers a wispy magical feature that creates a shiny beauty in the garden, especially in spring. Also, even though it pairs best with tulips, it is versatile and looks good with Peonies and ferns. To control it, you can yank it out after it blooms – this keeps them from ending up everywhere.
Under planting with Hedera helix (English Ivy)
This is another plant that thrives in the shade. But, it works best with other plants that it won’t choke out. The beauty of the English Ivy comes in four-fold – its proliferation in the shade, easy-to-maintain nature, leathery texture, and dark green colour. Even more, it easily covers slopes. So, if you have a garden of ferns, Peonies, Dogwood, and Birch on the east side of your house, English Ivy can be easily used as an underplant. I underplant my laurel hedging with ivy, as it covers the parched dry ground easily and prevents other weeds growing.
Under planting with Muscari (Grap hyacinth)
Though these pair just nicely with other spring bulbs, they won’t amount to much for the first few years. However, they can spread wildly, and before you know it, they form a thick carpet of white, purple, or blue beneath taller bulbs. So, what’s the secret to these hunger spreaders getting along underground with other bulbs without starving each other? Well, while larger bulbs are planted several inches deep, the Grape hyacinth’s bulb sits at a shallow depth in the ground. This way, there is enough room and nutrition for everyone.
Wrapping It Up
Well, there you have it! Now, you know what underplanting is, how to get started, and even how to work out what plant goes well with another plant.
So, go ahead and give your garden that extra pizzazz and enjoy the view!
