Some crops only become available for planting at gardenbeds at certain levels:
Wheat - level 1
Corn - level 3
Carrot - level 5
Onion - level 8
Tomato - level 11
Beans - level 13
Potato - level 15
Pumpkin - level 16
Cabbage - level 17
Chili - level 20
Lettuce - level 23
Strawberry - level 26
Kelp - level 27
Porphyra - level 28
Bryozoa - level 29
Garlic - level 30
Cucumber - level 36
Sunflower - level 42
Broccoli - level 54
Watermelon - level 60
Turnip - level 66
Spinach - level 72
Eggplant - level 78
Peanut - level 82
Sorghum - level 88
Kumquat - level 95
Soy - level 99
Rice - level 104
Pineapple - level 108
Sweet Pepper - level 114
Zucchini - level 120
Physalis - level 125
Portobello Mushroom - level 129
Chard - level 136
Blackberry - level 140
Basil - level 143
Cauliflower - level 147
Grapes - level 151