Apple tree / grow Nasturtium around the base to repel codling moth.

Apricots / Basil, Tansy, Southernwood

Asparagus / grow Basil,Parsley and Tomatoes

Basil / grow with Tomatoes

Beans / plant with Carrots,Cauliflower,Cucumber.     
  don't plant with Garlic ,Onions etc.....

Beetroot / Onions,Cabbage,Lettuce,Silverbeet & kholrabi

Broad Beans / Potatoes, Sweetcorn, Dill                                                                                                                                                             
Cabbage, Cauliflower, Broccoli

Aromatic plants, sage, dill, beets, rosemary, Beans, Celery, Onions, Potatoes.
don't plant with Strawberries or Tomatoes

Carrots / can be planted with Beans,Chives,Peas,Leeks,Onions & Lettuce

Celery/Tomatoes, Dill. Beans, Leeks, Cabbage, Cauliflowers

Chilli (Hot Peppers) / Basil, Oregano, Parsley, Rosemary

Chives / plant with Carrots,Parsley, Apples, Tomatoes

Comfrey / Plant around fruit trees

Coriander / Dill, Chervil, Anise, Cabbages, Carrots

Cucumbers / plant with Corn,Melons,Peas & Pumpkins
  don't plant with Potatoes

Foxgloves / Apples, Potatoes, Tomatoes

French Marigold / Tomatoes most vegetables.
 root secretions kill nematodes in the soil. Will repel white fly amongst tomatoes.

Fruit trees nettles, garlic, chives, tansy & Comfrey

Fuchsias / Basil, Gooseberries, Tomatoes

Garlic / plant near Tomatoes & Roses
helps keep aphids away from roses , repels cabbage butterfly

   don't plant near  Peas and beans

Grapes / Geraniums, Mulberries, Hyssop, Basil, Tansy

Leek plant with Carrot,Celery & Onion

Lettuce / Carrots, Onions, Strawberries, Beetroot, Cabbages 
Radishes, Marigolds

Marigolds / Lettuce, Potatoes, Tomatoes, Roses, Beans

Kills, nematodes and eel worm

Melons / Pumpkins,Rockmelons,Corn & Cucumbers

Mint / Cabbage, tomatoes
Deters white cabbage moth, deters ants and fleas (especially spearmint), will deter clothes moths.

Nasturtium / Zucchini,Cucumber, fruit trees
secrete a mustard oil, which many insects find attractive and will seek out, particularly the cabbage white moth. The flowers repel aphids and the cucumber beetle

Parsley / Tomato, asparagus, roses
Deters rose beetle, improves tomato and asparagus.

Parsnips / Peas, Potatoes, Peppers, Beans, Radishes, Garlic

Peas / Carrots, turnips, corn, beans, radishes, cucumbers, most vegetables and herbs
don't plant Onions,Potatoes & Garlic near Peas

Potato / Alyssum,Peas, Beans, Cabbage, Sweetcorn, Broad Beans 
Green Beans, Nasturtiums, Marigolds, Foxgloves 
Horse Radish, Egg Plant

Alyssum attracts beneficial wasps and acts as a living ground cover

Pumpkin Corn,Melons
  don't plant near Potato

Pyrethrum / Great repelant in the vegie paich

Radish / Peas, nasturtium, lettuce, cucumbers, spinach
  Radish attracts leaf minor away from spinach

Blackberries, tomatoes, potato

Roses / Garlic, Chives, Parsley, Mignonette lettuce.
.
Sage / Rosemary, Cabbage and Carrots
   Deters cabbage moth and carrot fly

Silverbeet / Beetroot, Parsnip Tomato, Lavender, Brassicas (Broccoli, Cabbage, Cauliflower, etc.), Onion family (Chives, Garlic, Leeks, Onions, etc.), Lavender

Spinach / Strawberries,Broad Beans, Cabbage, Cauliflower, Celery, Eggplant, Onion, Peas, Santolina (Cotton Lavender)

Squash / Corn ,Pumpkin & Melon

Strawberries / Spinach, Borage, Lettuce

Sunflower /Cucumbers
    don't plant near Potato

Sweet Corn /  Potatoes, Peas, Beans, Cucumbers, Pumpkin, Squash
  Corn acts as a trellis.

Tansy / Fruit trees& roses
  repels moths, flies and ants. Plant beneath peach trees to repel harmful flying insects. Tansy leaves assist compost fermentation.

Thyme great in the garden
    Protects cabbages, improves growth and flavour of vegetables, general insect repellent.

Tomatoes / Asparagus, Parsley, Chives, onion, Broccoli, Sweet Basil, marigold, carrots, parsley.
   don't plant near  Kohlrabi, potato, fennel, cabbage

Turnip/ Peas, nasturtium, lettuce, cucumbers

Yarrow / Plant along borders and paths.  Enhances essential oil production and flavour