The following is a list of Gardening Cross Breed seed Combinations. To achieve a successful cross breed, you will need to use Thanalan Top Soil, the higher the grade, the better.

General Crosses for Crafting Mats

Apricot Kernels:
Honey Lemon Seeds + Prickly Pineapple Seeds
Prickly Pineapple Seeds + Rolanberry Seeds
Glazenut Seed + Sun Lemon

Azeyma Rose Seeds:
Linseed + Mandrake

Broombush Seeds:
Holone Gerbera + Almond
Nymeia Lily + Almond
Broombush + Almond

Glazenut Seeds:
Royal Kukuru Seeds + Apricot Kernels
Glazenut Seeds + Apricot Kernels

Halone Gerbera:
Azeyma Rose + Chamomile

Jute:
Star Anise + Almond
Jute + Mandrake
Broombush + Azeyma Rose

Nymeia Lily:
Almond + Mandrake
Jute + Linseed

Royal Kukuru:
Apricot + Honey Lemon
Royal Kukuru + Honey Lemon
Glazenut + Honey Lemon
Glazenut + Rolanberry

Star Anise:
Azeyma Rose + Mandrake
Star Anise + Linseed (flax)

Pearl Roselle
Shroud Tea Leaves + Star Anise
Shroud Tea Leaves + Jute
Mandrake + Eggplant Knight

Dalamud Popotos
Midland Cabbage + Dzemael Tomato

Chive
Pearl Sprout + Dalamud Popoto

Blood Pepper
Glazenut + Chive Seed

Chocobo Training Food
Chocobo Training food crossbreeds are not as reliable as the crafting mats as far as crossbreeding, but these are confirmed crosses, and the only way, other than buying the seeds, to obtain said seeds.

Curiel Root:
Krakka + Popoto
Krakka + Chamomile
Krakka + Mirror Apple

Sylkis Bud:
Krakka + Almond
Krakka + Dzemael Tomato
Krakka + Shroud Tea Leaves
Krakka + Apricot

Mimett Gourd:
Krakka + Prickly Pineapple
Krakka + Midland Cabbage
Krakka + Azeyma Rose
Krakka + Garlic

Tanta Plant
Krakka + Wizard Eggplant
Krakka + Honey Lemon
Krakka + Midland Basil

Pahsana Fruit
Krakka + Linseed
Krakka + Million Corn
Rolanberry + Krakka

Thavnarian Onion
Sylkis + Broombrush
Sylkis + Nymeia Lily
Mimett Gourd + Glazenut
Mimett Gourd + Nymeia Lily
Jute + Sylkis
Broombush + Curiel
Royal Kukuru + Sylkis
Royal Kukuru + Curiel Root

Gyshal Green
Krakka + Pearl Root
Krakka + Coerthas Carrott
Sylkis Bud + Krakka
Paprika + Krakka
Gyshal + Krakka
Thavnarian Onion + Krakka
Thavnarian Onion + Sylkis
Chocobo coloring snacks + any seed

Minions
2.3 brought us minions that can be grown in the garden.

Onion Prince:
Krakka + Mandrake
Mandrake + Wild Onion

King Tomato
Broombush + Krakka
Krakka + Jute
Sylkis + Almons
Mimmet Gourd + Almond

Garlic Jester
Garlic + Mandrake
Linseed + Chamomile

Mandragora Queen
Mandrake + Nymeia Lily

Eggplant Knight
Krakka + Star Anise
Linseed + Mandrake
Onion Prince + Krakka
Wild Onion + Wild Onion
Wizard Eggplant + Mandrake