Companion planting is the practice of growing plants side by side so they help each other with pests, pollination, shade or space, and in Sydney you can start any time from early spring once the soil warms. The biggest mistake is crowding plants together, so each one competes for water and light instead of helping its neighbour.
Gardeners have used these pairings for generations, though the evidence for some combinations is mixed, so treat them as a useful guide rather than a guarantee.
Key points
- The best time to start companion planting in Sydney is spring to early summer for warm-season crops such as tomatoes, and autumn for silverbeet and other cool-season leaves.
- You need little equipment: a trowel, compost, mulch and a plan that gives each plant enough space, sun and water.
- Check pet safety and water rules: onions, garlic and chives are commonly listed as toxic to pets, and watering must follow Sydney Water’s Water Wise Guidelines.
- A Sydney gardener charges about $52 to $115 per hour (October 2026) if you want help preparing beds or pruning larger plants.
What is companion planting?
| Term | Meaning | Why it matters |
|---|---|---|
| Companion plants | Plants grown together because they suit each other’s needs or protect each other | Good pairings can reduce pests and make better use of space |
| Trap crop | A plant that attracts pests away from your main crop | Protects vegetables without sprays |
| Companion herbs | Herbs such as basil, chives and parsley planted among vegetables | Strong scents may confuse pests, and flowers attract beneficial insects |
| Polyculture | A mix of different plants in one bed | Fewer problems than a single crop in rows |
| Antagonist plants | Plants that compete or harm neighbours, such as heavy feeders crowded together | Avoid pairing plants with clashing water or nutrient needs |
When to start companion planting in Sydney
| Season | What to do | Why |
|---|---|---|
| Spring (September to November) | Plant tomatoes, basil, marigolds and beans once frost has passed | Warm soil helps warm-season crops and herbs grow quickly |
| Summer (December to February) | Mulch, water early or late, and add herbs and flowers between crops | Mulch cools roots and flowers attract bees |
| Autumn (March to May) | Plant silverbeet, lettuce, onions and brassicas in mixed beds | Cool-season leaves thrive as nights cool |
| Winter (June to August) | Plan next season’s beds, add compost and prune lavender and perennials lightly | Rest the soil and prepare for spring |
| All year | Rotate crop families and keep notes on what worked in your garden | Reduces disease build-up and shows which pairings help |
What you need for companion planting
| Item | What it is for | Tip |
|---|---|---|
| Compost and well-rotted manure | Feeds soil and improves moisture holding | Heavy clay in western Sydney needs extra organic matter and a raised bed |
| Organic mulch | Keeps roots cool and suppresses weeds | Keep it clear of stems to prevent rot |
| Seedlings and seeds | The plants themselves | Buy from Bunnings, local nurseries or seed suppliers such as Yates |
| Trowel and watering can or hose | Planting and watering | Use a hand-held hose with an instant on-off trigger nozzle |
| Plant labels and a notebook | Track pairings and results | Note what thrived so you can repeat it |
| Stakes or trellis | Support tomatoes, beans and climbers | Fit supports before plants get large |
Companion planting: step by step
- Choose a sunny bed with at least six hours of direct sun and good drainage, and note which side gets afternoon shade.
- List the plants you want, and check each one’s mature size on the label (indicative — check the plant label) so you can space them properly.
- Pick pairings that suit each other, such as a tall plant beside a low one, or a deep-rooted plant beside a shallow-rooted one.
- Prepare the soil by digging in compost to about the depth of a spade, and remove weeds and rocks.
- Plant the main crop first, then add companions at the spacing on the plant label (indicative — check the plant label).
- Water in gently with a hand-held hose fitted with an instant on-off trigger nozzle, before 10 am or after 4 pm.
- Mulch with organic mulch, keeping it clear of the stems, and top up as it breaks down.
- Check the bed weekly for pests and thin crowded plants, and pick off pests by hand before they spread.
- Record what worked, and rotate crop families next season so the bed stays healthy.
Tomato companion plant ideas
Tomatoes are a classic starting point, and a tomato companion plant should handle the same sun and water without crowding the stems.
- Basil is the best-known tomato companion, and gardeners often plant it nearby for flavour and to deter some pests; see how to grow basil.
- Marigolds planted around the bed add colour and attract beneficial insects while using little space.
- Chives and parsley fit between tomatoes, but keep chives away from pets that chew garden plants.
- Low-growing lettuce under tall tomatoes uses shade and fills gaps, provided you water it regularly.
- Avoid planting tomatoes near other heavy feeders that compete for the same nutrients.
- Read growing tomatoes in Australia for timing, staking and feeding advice.
Silverbeet companion plants
Silverbeet grows well in cooler months, and good companion plants for silverbeet share its cool-season timing.
- Onions, garlic and spring onions grow in the same cool season and are commonly paired with leafy greens.
- Lettuce and rocket make shallow-rooted partners that fill gaps between silverbeet plants.
- Beans can share a bed in warmer weather, but give them a trellis so they do not shade the leaves.
- Brassicas such as cabbage and broccoli grow in a similar season, though keep them well spaced.
- Nasturtiums around the edge attract bees and add colour; keep them trimmed so they do not smother crops.
- Avoid crowding silverbeet with heavy feeders, and rotate crops each year; use the what vegetables to plant now guide to time your sowings.
What to plant with lavender in a border
Lavender wants full sun, sharp drainage and little water, so its best partners share those needs. Heavy clay and wet corners are poor choices.
- Rosemary grows in similar dry, sunny conditions and makes a good partner; see how to propagate rosemary.
- Sage, thyme and oregano suit the same free-draining soil and add herbs for the kitchen.
- Salvias and catmint add purple and blue flowers that attract bees and butterflies.
- Roses are a traditional pairing, with lavender at the foot of the bush, provided the soil drains well.
- Silver-leafed plants such as artemisia echo the colour of lavender foliage.
- Keep lavender away from thirsty plants such as hydrangeas, which need far more water.
Common companion planting mistakes
- Crowding plants so closely that they compete for light, water and nutrients instead of helping each other.
- Pairing sun lovers with shade lovers, such as lavender beside a thirsty fern.
- Expecting scented companions to replace all pest control; they help, but they do not guarantee protection.
- Planting onion-family plants where pets can chew them, since these are commonly listed as toxic; contact your vet if a pet eats them.
- Letting vigorous companions such as mint spread through the bed instead of growing them in pots.
- Skipping crop rotation, which lets soil diseases build up from one season to the next.
When to call a gardener or licensed specialist
- You have a large tree or citrus that needs pruning above head height, which is a job for a qualified arborist.
- You plan to prune or remove a large tree, and you need to check your council’s tree rules first.
- You want paid weed spraying, since in NSW anyone spraying weeds for fee or reward needs an EPA ground applicator licence (routine garden maintenance has an exemption).
- You have insects or other pests that are damaging crops, so book a licensed pest controller rather than mixing sprays.
- You need irrigation plumbing connected to the mains or backflow work, which is for a licensed plumber.
- You want help preparing beds, mulching or tidying, and would rather hire a local gardener.
Companion planting cost in Sydney
| Job | Low | Typical | High |
|---|---|---|---|
| Sydney gardener (per hour) | $52 | $75 | $115 |
| Tree pruning (per tree) | $230 | $520 | $1,375 |
| Small hedge trimming (per job) | $69 | $115 | $205 |
| Garden clean-up, half day | $170 | $290 | $460 |
| Garden clean-up, full day | $320 | $520 | $805 |
| Weed removal (per hour) | $57 | $75 | $105 |
Prices include GST and reflect Sydney metro rates for October 2026. Plant and mulch costs depend on what you buy.
FAQ: companion planting questions
What is companion planting?
Companion planting means growing different plants together so they benefit each other, for example by deterring pests, attracting pollinators or sharing space. Many pairings come from traditional gardening, and results vary by garden. Start with a few simple combinations and keep notes.
What to plant with lavender in a border?
Plant lavender with other sun-loving, drought-tolerant plants such as rosemary, sage, thyme, salvia and catmint. Roses also make a classic partner. Give lavender full sun and sharp drainage, and keep it away from thirsty plants that need frequent watering.
What to plant with lavender?
Good partners are rosemary, sage, thyme, oregano, salvia, catmint and silver-leafed plants. They share lavender’s need for sun and free-draining soil. Avoid shady spots and wet corners, and mulch lightly with gravel or pea straw rather than thick organic mulch around the stems.
Does companion planting really work?
Some pairings help, such as flowers that attract beneficial insects or tall plants that shade low ones. Others have little evidence behind them. Good spacing, healthy soil and crop rotation matter more than any single pairing, so treat companions as an extra rather than a cure-all.
Next step: get help with your garden beds
If you would rather hand over bed preparation, mulching or pruning, we can help. Sydney gardeners typically charge about $52 to $115 per hour (October 2026), and tree pruning typically costs about $230 to $1,375 per tree. Start with our what vegetables to plant now guide, or request a pruning quote for your Sydney garden.
