Ordinary kale is biennial. It grows leaves the first year, throws up a flower spike the second, sets seed and dies. Perennial kale is a small group of named clones that mostly skip that ending, either because they rarely flower or because they resprout after they do. Plant one this fall and you can still be picking from the same plant in 2031.
The honest version is that "perennial" here means short-lived perennial. Most of these plants hit their stride in year two and start losing vigor somewhere between year five and year eight, at which point you replace them from a cutting off the parent. That is still a very good deal compared with sowing kale every spring, but it is not a plant-it-and-forget-it shrub.
Here is what this guide covers:
Key Takeaway
Almost none of these plants come true from seed, and several never set viable seed at all. You buy a rooted cutting or a plant, then you propagate your own from it, forever. If a seed packet is selling you "perennial kale seeds", you are probably buying a mix of hardy annual kales instead.
The choice comes down to how much space you have and how cold your winters get. The Royal Horticultural Society lists these forms under Brassica oleracea var. ramosa, the branching perennial kale group, though tree collards sit slightly apart and sea kale is a different genus entirely.
| Cultivar | Size | Lifespan | Notes |
| Daubenton | Dome, 3 ft high and wide | 5–6 years | Tender small leaves, best for small gardens |
| Daubenton variegated | Slightly smaller dome | 4–6 years | Cream-edged leaves, less vigorous |
| Taunton Deane | Up to 6 ft, 3–5 ft wide | 5–8 years | Top-heavy, needs a real stake |
| Purple tree collard | 6–10 ft, 3 ft wide | Reported to 20 years | Rarely flowers, mild climates |
| Merritt collard | 4–10 ft | Long-lived | Hardy to about 20°F, leaves to 2 ft |
| Sea kale | 2–3 ft clump | Genuinely long-lived | Different genus, blanched shoots eaten |
Sources: RHS, Brassica oleracea var. ramosa, Project Tree Collard, Tree Collard Varieties, UC Marin Master Gardeners, Collard. Lifespans come from nursery and practitioner experience rather than replicated trials, so treat them as guidance and not guarantees.
For most US gardeners starting out, Daubenton is the sensible first plant. It stays a manageable 3-foot dome, the leaves are noticeably more tender than annual kale, and it roots from cuttings almost embarrassingly easily. Taunton Deane gives you far more leaf but grows into a genuinely large, top-heavy plant that will lean over and snap in a gale if you do not stake it properly from the start.
This is where you have to read carefully, because nearly every hardiness figure for perennial kale comes from a nursery rather than a trial, and most of them come from maritime Britain. Taunton Deane is commonly listed as hardy to about 14°F. Tree kale suppliers cite 14°F down to 5°F "quite easily", with the caveat that protection is advisable in severe winters and that deep planting plus mulch matters for the first two winters. Merritt collard is given as hardy to at least 20°F.
Survival and thriving are different things, and the gap between them is where US gardeners get caught out. A British 14°F is a brief overnight low in damp air with no frozen ground. An Iowa 14°F is a fortnight with the soil frozen solid and a wind that strips leaves. Those are not the same event, and a zone number cannot tell them apart.
Two practical rules follow. In zone 7 and warmer, treat these as reliably perennial outdoors. In zone 6 and colder, treat the outdoor plant as expendable and keep a rooted cutting somewhere frost-free every winter. Practitioners who have grown these for years do exactly this, and it is the single habit that separates people who still have their plant in year five from people who lost it in a cold snap. If you want the wider picture on which crops survive what, our guide to cold hardy vegetables and frost tolerance covers the temperature bands for the whole vegetable garden.
Common Mistake to Avoid
Buying "perennial kale" seed. Daubenton and most Taunton Deane clones rarely or never set viable seed, and where they do, the seedlings do not come true. Seed sold under that name is generally a hardy annual or biennial kale that will bolt in its second year like any other. Buy a rooted cutting or a live plant from a nursery that names the cultivar, then propagate your own.
This is the skill that matters, and it takes about ten minutes. Perennial kale roots from stem cuttings readily enough that most people end up giving plants away.
Take a side shoot 4 to 6 inches long
Choose a firm, non-flowering side shoot rather than the softest new growth. Cut cleanly just below a leaf node with sharp snips. Spring and early fall both work; fall cuttings overwinter indoors and go out in spring.
Strip the lower leaves, keep two or three at the top
Too much leaf and the cutting dries out before it roots. Too little and it has no energy to root at all. Two or three small leaves is the balance.
Pot into moist mix, or a jar of water
A 4-inch pot of gritty potting mix in a shaded spot works well. Plain water on a windowsill also works and lets you watch the roots form, though water roots are more fragile in transplanting. Rooting hormone is optional and not usually necessary.
Keep two spares alive at all times
One in the ground, one in a pot somewhere sheltered, one to give away. Total cost is a pot and some mix, and it is the difference between losing a cultivar and shrugging off a bad winter.
Why This Works: Stacking Functions and Perennial Systems
Permaculture keeps pushing annual beds toward perennial systems because a plant that stays put builds soil relationships an annual never gets time to form. A five-year-old kale sits in undisturbed soil with an established root network and fungal associations, which is why it comes back earlier in spring and pushes through drought better than a seedling. You are trading a little yield per square foot for a lot less work, which is the same trade a food forest makes at a larger scale.
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Send Me the ListPests, and the reason is structural. A perennial brassica is never rotated. It sits in the same soil year after year, which is precisely the situation every extension pest guide tells you to avoid with the cabbage family.
Cabbage aphid is the main nuisance. It overwinters on the plant itself rather than arriving fresh each spring, so populations build across seasons on a plant you never pull up. UC IPM covers monitoring and the natural enemies worth encouraging. In practice, a hard cut-back in late winter removes most of the overwintering colonies along with the tired growth, and it is the single most useful piece of annual maintenance.
Clubroot is the more serious risk and the one worth thinking about before you plant. NC State Extension advises rotating infested ground away from brassicas for a minimum of four to seven years, which is impossible with a plant that lives there permanently. The pathogen favors wet, acidic soil, germinating between roughly 64 and 77°F below pH 7.0. If clubroot is already present on your plot, do not site perennial brassicas there. If it is not, keep the pH up and the drainage good, and site the plant where you would be willing to lose the ground for a decade.
Key Takeaway
Cut hard in late winter, every year. It removes overwintering aphids, stops the plant getting leggy and woody, and triggers the flush of tender new growth that makes these plants worth having. A perennial kale left uncut for three years becomes a tall, sparse, aphid-covered disappointment.
Generally no, and several cultivars do not set viable seed at all. Daubenton rarely flowers, and Taunton Deane and purple tree collard are shy flowerers, which is exactly what makes them perennial. Where flowering does happen, brassicas cross readily with any other brassica nearby, so seedlings are a lottery rather than a copy of the parent. Seed sold as perennial kale is usually a hardy annual or biennial type. Buy a named rooted cutting or plant, then take your own cuttings from it.
Daubenton types typically give five to six good years before vigor drops noticeably, and Taunton Deane is commonly reported at five to eight. Purple tree collards in mild California conditions have been reported living up to twenty years, though that figure comes from individual specimens rather than trials. In all cases the plant does not die suddenly; it gradually produces less and gets woodier. Take a cutting in year four and you will never have a gap in supply.
Reported figures cluster around 14°F for Taunton Deane and tree kale types, with some suppliers claiming down to 5°F, and Merritt collard listed at about 20°F. Read those numbers as survival in a mild maritime winter rather than a promise for a continental one, because most originate from British and coastal Californian nurseries. Zone 7 and warmer is comfortable territory. In zone 6 and colder, mulch deeply, plant in a sheltered spot, and always keep a rooted cutting under cover as insurance.
Cut a firm side shoot 4 to 6 inches long just below a leaf node, strip all but the top two or three leaves, and push it into moist gritty potting mix in a shaded spot. Keep it damp and out of direct sun. Roots usually form within a few weeks. A jar of water on a windowsill also works and is useful for seeing progress, though water-formed roots transplant less well. No rooting hormone is needed. Spring and early fall are both good windows.
Both are perennial forms of Brassica oleracea, but tree collards are taller, more tender and more heat tolerant, typically thriving in USDA zones 7 to 10 and growing 6 to 10 feet on a single stout trunk. Perennial kales like Daubenton are shorter, bushier and better suited to cool, damp climates. Tree collards also tend to have a milder, sweeter leaf. Both are propagated the same way, and both fit the same role in a permaculture garden design, alongside other perennial vegetables and within a planted guild.
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