Sweet potato greens as a hot-season leaf crop: cuttings, first harvest, regrowth

When the hot season arrives, leafy greens such as Chinese kale and lettuce tend to bolt or wilt, but sweet potato tips get better. Sweet potato grows well in hot, humid weather and in dry spells, and one planting of vine cuttings gives tips to pick for months.

This lesson draws on US university extension guides and ECHO: how to plant cuttings, when to start picking, where to cut for regrowth, and what you trade if you want roots as well.

Why sweet potato suits the hot season

• The UC Davis guide says sweet potato grows in many climates, hot and humid as well as dry. The vines cover the ground like a mulch, keeping moisture in and weeds down.
• The University of Arkansas at Pine Bluff (UAPB) guide says it tolerates disease, pests and high moisture better than many leafy vegetables grown in the tropics, and tips can be cut several times a year.
• Washington State University (WSU) found the greens can be picked right through summer, when many other leafy greens decline in quality.

For leafy greens that dislike heat, see growing leafy greens in hot weather.

Planting vine cuttings

In the tropics sweet potato is grown from cuttings taken from existing vines. ECHO’s advice:

1. Cut vine tips 30-45 cm long from vigorous growth, neither too soft nor old and thick, and free of disease. There is no need to strip the leaves.
2. If you have time, bundle them and keep them moist in the shade for 1-3 days so roots start, but plant within 24 hours of preparing them.
3. Plant at an angle with about two-thirds of the cutting below the soil.
4. Water often for the first 1-3 weeks. Once new growth starts, water only when you see the leaves begin to wilt.

For a greens crop, UC Davis advises not planting too close: 30-40 cm between plants and 40-50 cm between rows.

ECHO warns root growers that too much nitrogen gives lush leaves and small roots. If you are growing for greens, that works in your favour; top up with compost now and then.

When to pick and where to cut

Item	Figure	Source
First harvest	45-90 days after planting	UC Davis
Vine length before cutting	at least 30 cm	WSU
Tip length to cut	10-15 cm from the end	WSU
Recutting	about every 2 weeks, or every 10-15 days	WSU, UAPB
Per plant	1-2 of the longest vines, leaving about 10 cm to regrow	UC Davis

Older leaves and stems are tough and not pleasant to eat; take only the tender tips that snap easily. Use them quickly. If not, refrigerate them, or stand the stems in water somewhere cool and dark. More in keeping vegetables fresh.

Worked example: how many tips from a 1 x 1.4 m bed

Say the bed is 1 m wide and 1.4 m long.

1. With 45 cm between rows, you fit 2 rows, about 27 cm in from each edge.
2. With 35 cm between plants along 1.4 m, you fit 4 plants per row, 8 plants in all.
3. Start cutting on day 60 (inside the 45-90 day window) and recut every 14 days. By day 120 you cut on days 60, 74, 88, 102 and 116: 5 rounds.
4. Take 2 tips per plant per round: 8 × 2 = 16 tips. WSU notes a market bunch is about 15-20 stems, so each round gives roughly one bunch.
5. Five rounds give 16 × 5 = 80 tips, about 4-5 bunches over 2 months.

If you want picking more often, plant a second bed about 2 weeks after the first so the rounds alternate.

Greens only, or roots too?

Cutting tips takes food away from the roots. In WSU trials, removing all tips every 2 weeks over various periods cut root yield by 47-61% compared with plants left uncut.

Goal	How to pick tips
Greens only	Cut on schedule as much as you like; ignore the roots
Greens and roots	Pick lightly, or wait until 12 weeks after planting, and cut all the tips just before digging roots, which doesn’t affect them
Mainly roots	UC Davis warns against cutting too often, or the roots grow slowly

Decide what the bed is for before you plant. For greens, cut freely. For roots, accept fewer greens.

Eating them

WSU describes sweet potato greens as similar to spinach, eaten fresh, stir-fried or steamed. UAPB lists B vitamins, beta-carotene, iron, calcium, zinc and protein among their nutrients. UC Davis suggests cooking briefly, cutting into small pieces, and using a little oil, because vitamin A is absorbed better with some fat. See cooking vegetables to keep their vitamins.

Common mistakes

• Confusing it with potato leaves. Sweet potato is in the morning glory family and its tips are edible; potato is a nightshade and its leaves are not food.
• Planting too close. Vines compete and tips stay small. 30-40 cm apart works well.
• Cutting the whole plant down. Leave about 10 cm so it can regrow.
• Picking old leaves. They are tough. Take only the tender 10-15 cm tips.
• Letting new cuttings dry out. Water often for the first 1-3 weeks; only once established does it tolerate drought.

Sources

• Sweetpotato Greens (Growing Sweetpotatoes in Western Washington) — Washington State University Extension
• Sweet potato leaves for family nutrition: Overview of research — Horticulture Innovation Lab, UC Davis
• Nutritional and Medicinal Qualities of Sweetpotato Tops and Leaves (FSA6135) — University of Arkansas at Pine Bluff
• Root and Tuber Crops (Amaranth to Zai Holes) — ECHO