For a big leafy green, you can’t beat tree collards. Tree collards’ large leaves turn purple in colder weather and are sweetest at this time, making it an ideal crop for the Pacific Northwest. Tree collards grow quite tall (6 to 8 feet) and will need staking. Although the purple leaves are sweeter, it’s best not to harvest them all at once if you want to maintain a regular harvest schedule. The leaves are extremely nutritious and are used in much the same way as other leafy greens like kale or cabbage, except they’re much sweeter. Both the leaves and stems are edible.