Filling large planters with your favourite flowers is a great way to create maximum interest in your outside space. But there are a few things to consider before you get started. Our handy guide reveals the tried and tested ways to successfully plant flowers in large planters.
Important things to consider before you plant flowers in large planters
- Location – think about which flower varieties you plan to plant. Are they sun-worshippers or shade lovers? Position your large planter in a location that will enable your flowers to thrive.
- Choice of flowers – if you plan to combine a few varieties it’s best to choose a range of flowers that enjoy the same conditions. Avoid pairing plants that enjoy full sun and lots of drainage with those that require shade and moist soil.
- Which planter? Planters come in all shapes, sizes and colours. Pick plant pots and containers that will complement the flowers that you plan to plant and don’t be afraid to experiment with different planter heights and widths.
- Drainage. To help your flowers bloom, always choose planters with drainage holes in the bottom and ideally, add some extra drainage material.
Find more tips on what to put at the bottom of a planter for drainage in our helpful blog.
How to fill the bottom of a large planter
When you plant flowers in a large planter it can become extremely heavy. Because of this, it’s a good idea to fill the lower third of the planter with filler material before adding any compost and soil. Not only does this lighten the weight of the planter, it also reduces how much soil you will need to use. Plus, filler materials will also help provide extra drainage.
To fill the bottom of a large planter, simply use one or more of the following materials:
- Styrofoam packing peanuts
- Natural materials e.g. bark, pine cones, twigs
Always opt for non-toxic materials that will not disintegrate quickly.
Add a layer of weed control fabric or newspaper between the filler material and compost.
Top tips of how to plant flowers in a large planter
1. Position your planter before filling it. Large planters become very heavy once filled with soil and plants, so position your planter in its final location before getting started.
2. Water your plants thoroughly before you position them in the large planter.
3. Consider the direction that your planter will face and whether you will see all sides of the planter, or for example, just the front. This will help determine how to position your plants.
4. Plant the largest plant first. As a rule of thumb, when planting flowers in large planters, you should always position your largest plants first. This ensures that the largest plant is given enough planting space. You can then fill in any gaps with smaller plants.
5. It’s best to plant each plant at around the same depth as the original pot that it was previously growing in. Place each plant into a large planter and then firm with soil.
How to arrange flowers in a large planter
There is a tried and tested way to arrange flowers in a large planter. In fact, gardeners have been using the process of choosing a thriller, fillers and spillers to arrange flowers in large planters, containers and hanging baskets for years. So what is it all about?
Your thriller plant should be the star of the show. Generally, it should be tall and upright with eye-catching textures, colours or movement. A thriller plant can be placed in the centre of your large planter and underplanted with flowers that bear complementary colours or styles. Placing a thriller plant to the back or side of a large planter will also help to create unique and interesting focal points.
Why not try:
Agapanthus ‘Brilliant Blue’ is another wonderful choice. This stunning African Lily can reach up to 1.5m in height. Its beautiful blue flowers combine perfectly with other blue, purple and white filler plants.
Sun-loving Flax Lily ‘Sundowner’ is a perfect thriller plant for Mediterranean and tropical-themed gardens. With its sword-shaped green and pink foliage, and striking yellow flowers, this fiery Phormium is guaranteed to add drama to any large planter.
Fillers make less of a statement than a thriller plant, but that doesn’t mean they have to be boring! Filler plants should add volume and texture to the planter. Choose plants that are smaller than your thriller plant to ensure that they don’t overpower it. As fillers are there to help accentuate your thriller plant and to fill up any gaps, for maximum impact add several filler plants into your planter.
Why not try:
For cool-toned large planter arrangements, Lobelia ‘Sapphire’ is ideal. Incredibly easy to maintain, this pretty royal-blue annual will easily fill any gaps in your container.
Bidens ‘Bee Happy Red’ is a charming annual that will add cheery orange and sunshine tones to any arrangement.
Finally, every large planter should contain at least one spiller – an attractive plant that will literally spill over the side of your container. Spillers should not be overlooked. Their cascading habit softens and adds interest to any large planter.
Why not try:
The variegated tones of Hedera Helix ‘Clotted Cream’ will complement lots of thriller and spiller plants.
Trailing Fuchsia ‘Sarah Eliza’ Southern Belle has gorgeously soft pink and cream double flowers that will hang elegantly over any planter.
Commonly Asked Questions
How much should you water flowers in a large planter?
It can be very tempting to overwater flowers in large planters. However, large planters filled with soil will take a lot longer to dry out than smaller planters. So whilst the topsoil may appear and feel dry to the touch, the deeper layers of soil are likely to still be damp enough for your plants’ root systems to survive.
A good way to guide the moisture levels in your soil is to slide a finger into the soil as far as it will go. If the soil feels damp at this level it’s best to wait and not water your flowers. Check the soil regularly as fluctuations in temperature can alter the soil evaporation process and how thirsty your plants are.
How do you change the soil in a large planter?
To change the soil in a large planter there’s no need to remove it all. Simply remove the top layer of old soil about once a year and replace it with fresh soil and compost.
Nicola Clements has been working with brands and publications in the gardening and lifestyle sectors for many years. As well as regularly writing for The English Garden‘s website, Nicola is also a contributing gardening editor to Wildflower magazine. In her spare time, Nicola can be found pottering in her garden, where she hones her skills, ready to pass on her expert advice to amateur and seasoned gardeners.