A beautiful pot on a terrace is only as good as what happens inside it. The planting — the drainage layer, the substrate, the choice of plant, the aftercare — determines whether a pot looks magnificent for years or starts declining by the second season. Getting these fundamentals right takes no special expertise, just a clear understanding of what each step is for.
Whether you're planting a flowering perennial, a Mediterranean tree, or a seasonal display in one of our glazed stoneware or terracotta pots, the principles below apply. They're the same ones I follow when setting up container plantings in the gardens I design across Belgium — from compact urban terraces in Brussels to larger private gardens in the Brabant Wallon and Vlaams Brabant.
Choosing the right pot
Material matters for plants, not just aesthetics
The pot's material directly affects how your plant grows. Terracotta and unglazed stoneware are porous — they allow the rootball to breathe and regulate moisture naturally, which is excellent for drought-tolerant plants and Mediterranean species like olives and lavender. Glazed stoneware and ceramic retain moisture more effectively, making them better suited to plants with higher water needs. If you're unsure which material suits your planting intention best, our piece on structuring a terrace with large terracotta pots goes into the design logic in more detail.
Drainage is non-negotiable
Every pot you plant in must have at least one functioning drainage hole at the base. Without it, water accumulates at the root zone, starves the roots of oxygen, and kills the plant — often before any visible symptom appears above ground. Check the hole is clear before planting, and never seal it with a saucer placed permanently underneath. If you use a saucer, empty it after rain or watering so water doesn't stand for more than a few hours.
Preparing the pot before planting
Building the drainage layer
Before adding any substrate, place a drainage layer at the base of the pot. This layer serves two purposes: it keeps the drainage hole clear of compacted soil, and it creates an aerated zone that prevents root rot even if the pot temporarily retains more moisture than expected.
For the drainage layer, use one of the following:
- Expanded clay aggregate (billes d'argile) — the most reliable and reusable option, available at any garden centre. Fill the bottom third of the pot for large containers, or 8 to 10 cm for smaller ones.
- Broken terracotta or ceramic shards — a traditional method that works well, particularly for large statement pots where the weight of clay aggregate would be excessive.
- Gravel or coarse grit — effective, though heavier than expanded clay.
Cover the drainage layer with a sheet of geotextile fabric before adding substrate. This prevents soil from washing down into the drainage layer over time while still allowing water to pass through freely.
Choosing and using the right substrate
Standard all-purpose potting compost is not always the right choice. Match the substrate to the plant:
- Mediterranean trees and shrubs (olive, bay, citrus, rosemary, lavender): use a free-draining substrate formulated for Mediterranean plants, or mix standard potting compost with 30% coarse horticultural grit. These plants evolved in dry, stony soils — heavy, moisture-retentive mixes will cause root rot over time.
- Flowering perennials and annuals (hydrangeas, agapanthus, geraniums, tulips): a high-quality universal potting compost with good water retention works well. For acid-loving plants like hydrangeas, use ericaceous compost.
- Trees and large shrubs in substantial containers: a loam-based compost (such as John Innes No. 3) provides better structural support for larger root systems and doesn't break down as quickly as peat-based mixes.
Fill the pot leaving enough space for the plant's rootball with 3 to 5 cm of clearance below the rim — this prevents water from running straight off the surface before it can penetrate.
Planting: the right technique
Place the plant at the centre of the pot. The top of the rootball should sit slightly below the pot rim — never mounded above it, which causes water run-off and exposes roots to drying out. Fill in around the rootball with substrate, firming gently with your fingers to eliminate large air pockets without compacting the mix.
Water thoroughly immediately after planting. This settles the substrate around the roots and helps the plant begin to establish. For large trees or shrubs in substantial pots, a second watering the following day is worthwhile to ensure the entire root zone has been saturated.
Aftercare: the four essentials
Watering
Container plants cannot access groundwater — they depend entirely on what you give them. During warm and dry periods, most planted pots will need watering every one to two days. In winter, reduce frequency significantly but never allow the substrate to dry out completely — even dormant roots need some moisture. Always check the substrate a few centimetres below the surface before watering: if it's still moist, wait. Consistent overwatering is far more damaging than occasional under-watering.
Fertilising
Potting compost contains nutrients for approximately six to eight weeks after planting. After that, container plants need regular feeding. Use a balanced liquid fertiliser every two weeks during the growing season (spring through summer), switching to a low-nitrogen formula in late summer to help woody plants harden off before winter. Slow-release granular fertilisers applied once in spring are a low-maintenance alternative.
Winter protection
Even in a frost-resistant pot, the plant inside may not be hardy. Tender plants — citrus, bougainvillea, many figs — must be brought inside before the first frost. For plants that can tolerate light frost but not hard freezes, wrap the pot in horticultural fleece or jute, which insulates the root zone without suffocating the plant. Raising the pot slightly off the ground on feet or wedges during winter also helps — it prevents the base from freezing onto a cold hard surface and improves drainage if the saucer fills with icy water.
The plant protection concern is separate from pot protection. Our guide to caring for garden pots by material covers what to do with terracotta, glazed stoneware, concrete, and zinc containers over winter specifically.
Rotation
Turn pots a quarter rotation every two to three weeks during the growing season. Plants grow towards their light source, and a pot that never moves will develop unevenly — one side dense and flowering, the other sparse and reaching. Regular rotation ensures a balanced, symmetrical plant that presents well from all angles. This is particularly important for statement pots on a terrace that are viewed from multiple directions.
Monitoring: what to watch for
Check your container plants regularly — not just to water them, but to observe. The early signs of stress (yellowing leaves, wilting that doesn't recover after watering, discoloration at the leaf margins) are far easier to address when caught early. Most container plant problems fall into one of three categories: watering imbalance, nutrient deficiency, or root congestion. If a plant has been in the same container for more than two to three years and growth has slowed significantly, it's likely pot-bound and ready for a larger container or a root pruning.
The planted pot as a complete composition
At Art for Garden, we think of a planted pot as a complete object — the vessel, the plant, and the space it occupies are inseparable. A beautifully thrown glazed stoneware jar deserves a plant chosen to complement its proportions and material, placed where it can be seen properly, and tended so it stays at its best. The care described here is the part of that composition that happens after the pot is in place — and it's what determines whether the object continues to give pleasure year after year.
If you're thinking about how to use large pots as structural elements in a terrace or garden design — rather than simply as individual plant containers — our piece on potscaping with large terracotta pots develops that idea in detail. And if the relationship between living plants and permanent garden art interests you, The Garden as Living Art approaches the same question from a different angle.
Questions about which plants suit a specific pot, or which containers from our collection work best for a tree planting? Get in touch — we're glad to help.
FAQ — Planting in garden pots
How deep should the drainage layer be at the bottom of a pot?
As a general rule, aim for 8 to 10 cm of expanded clay aggregate or equivalent in pots up to 40 cm tall. For large statement pots (60 cm and above), filling roughly the bottom third with drainage material is appropriate. Always cover the drainage layer with geotextile fabric before adding substrate to prevent soil from washing down and blocking it over time.
Can I use the same potting mix for a Mediterranean olive tree and for flowering perennials?
Not ideally. Mediterranean trees need a free-draining, relatively lean substrate — a standard moisture-retentive potting compost will hold too much water around the roots and cause problems over time. Mix standard compost with 25 to 30% coarse horticultural grit for Mediterranean species, or use a dedicated Mediterranean plant compost. For flowering perennials, a quality universal potting compost is usually sufficient.
My pot plant's leaves are yellowing — what's wrong?
Yellowing leaves in container plants most commonly indicate one of three things: overwatering (check that drainage is functioning and reduce frequency), nutrient deficiency (particularly nitrogen or iron — apply a balanced liquid feed or, for acid-loving plants showing yellowing between the veins, an ericaceous feed), or root congestion in an undersized pot. Check the drainage hole first — a blocked hole causing waterlogging is the most frequent culprit and the easiest to fix.