Most kitchen scrap regrowing advice treats everything the same: submerge the base in water, watch it grow, feel good about yourself. The problem is that “it grows” and “it produces meaningful food value” are not the same claim. Scallions and ginger rhizomes will save you real money. Romaine lettuce will grow some scraggly inner leaves for two weeks and then stop. The difference matters if you’re trying to decide whether to set up a rotation of regrow jars or just throw the scraps in the compost.
This article separates the high-value cases from the low-value cases with actual math. Every retail price comes from USDA AMS market data. Every yield estimate is based on what you’ll realistically harvest, not what the best-case scenario produces.
Scallions: The Only Regrow That Consistently Pays
Green onions (Allium fistulosum) are the most reliable kitchen regrow by a wide margin. The math is straightforward because the turnaround is fast and the yield is measurable.
Buy a bunch of scallions at the grocery store. USDA AMS retail data shows scallion prices ranging from $0.99 to $1.89 per bunch depending on region and season, with a national median around $1.39 (USDA Agricultural Marketing Service, Retail Produce Price Data, 2024). That bunch typically contains 6-8 stalks.
Cut the scallions 2 inches above the roots. Place the root ends in a glass with about an inch of water. Set them in a window with reasonable light. In 7-10 days you have full-length green tops again. A $1.39 bunch effectively becomes $2.78 in usable green onions before you’ve spent anything.
The critical detail: change the water every 2 days. Stagnant water leads to bacterial slime on the roots and reduces regrowth vigor. After 3-4 regrowth cycles - roughly 4-6 weeks from the original purchase - the root system shows declining vigor and flavor starts to weaken. At that point you replant in soil or start fresh. The bulb bases planted in soil after water-rooting will continue producing for another 6-8 weeks before they need to be replaced.
Running 4-6 jars in rotation changes the economics considerably. With 4 jars each holding one bunch’s worth of roots, you’re harvesting from one jar every 2-3 days on average. Over a 2-month window, a $5-6 initial investment in scallion bunches produces 12-16 additional harvests at $1.39/bunch retail equivalent - roughly $17-22 in produce value. The jars cost nothing if you already own them. The only ongoing cost is the occasional fresh bunch to maintain the rotation when root vigor declines.
If you cook with scallions more than twice a week, this is worth doing. If you use them occasionally as a garnish, a single jar is still worth the effort. You are spending 30 seconds every 2 days changing water in exchange for a consistent free supply of fresh green onions. For planting the spent root ends in garden soil and growing them out to full size, see the scallion growing guide.
Ginger: High Value, Slower Timeline
Store-bought ginger (Zingiber officinale) is genuinely plantable, and the return on investment is among the highest of any grocery-to-garden conversion. The catch is the timeline: this is a 7-9 month commitment, not a 2-week countertop project.
Grocery store ginger sells for $3-7/lb depending on season and region (USDA AMS, Specialty Crops Terminal Market Reports, 2024). An inch-long knob of ginger - the kind you might have left over after a recipe - weighs roughly 0.15-0.25 lb and costs $0.50-1.50 at that retail rate.
That same piece of ginger, planted in a container in spring after the last frost date, will produce 1-2 lbs of fresh rhizomes by fall. Grocery store fresh ginger at $3-7/lb means that $0.75 starter piece yields $3-14 in harvest value. The ROI range is wide because ginger yield is sensitive to container size, heat, humidity, and how long you let it grow.
The practical protocol: select a piece with at least one visible “eye” (a small nub pointing outward - the same as what you’d look for on a potato). Soak it in water overnight to leach out any surface treatments. Plant 2-4 inches deep in well-draining potting mix. Ginger needs warmth to get going - soil temperature below 60°F will result in slow or no sprouting. In most of the continental US, that means waiting until late April or May, or starting indoors under lights in March.
The organic caveat is real. Conventional ginger and turmeric from grocery stores are frequently treated with growth inhibitors to prevent sprouting during distribution and storage. You may get lucky with conventional ginger from a well-stocked store where turnover is high, but the success rate with organic ginger is meaningfully higher. If you want a reliable outcome, spend a bit more on organic. At $5-10/lb for organic ginger (depending on your source), you’re still at $0.75-2.00 for a starter piece that can return $6-14 in harvest. The economics hold.
See the full growing guide at ginger growing guide.
Turmeric: Even Better Returns Than Ginger
Turmeric (Curcuma longa) follows the same protocol as ginger and frequently outperforms it on ROI because the retail price for fresh turmeric root is higher. Specialty grocery stores and co-ops sell fresh turmeric at $8-15/lb (USDA AMS Specialty Crop Market News, regional markets, 2024). Dried and ground turmeric at natural food retailers runs $4-8 per ounce.
The math: a $1 piece of grocery store turmeric rhizome - roughly 0.1-0.15 lb - can produce 1-1.5 lbs of fresh rhizomes by fall under good conditions. At $10/lb for fresh specialty-market turmeric, that’s a 10x return on your starting investment in plant material.
Turmeric is more temperature-sensitive than ginger. It requires sustained warmth through the growing season, which makes it better suited to containers that can be moved than to northern in-ground gardens. Containers also solve the harvesting problem - you can dump the pot in fall and separate the rhizomes easily without digging. Leave a few small rhizomes in fresh soil and overwinter the container indoors for a head start the following spring.
Turmeric from specialty Asian grocery stores often has better sprouting success than grocery chain produce sections, likely because of higher turnover and less aggressive treatment. Fresh turmeric at Asian markets is also typically priced lower - sometimes $2-4/lb - which makes the starter cost even more attractive.
See turmeric growing guide for planting depth, fertilizer timing, and container sizing.
Sweet Potato Slips from Grocery Tubers
Sweet potato slips - the rooted sprouts you plant to grow sweet potatoes - sell for $3-6 per dozen from most mail-order nurseries and garden centers. A single grocery store sweet potato can produce 8-12 of those slips if you give it the right conditions, which means you’re getting $2-6 in transplant value from a $1.50-2.00 sweet potato.
The method: suspend the sweet potato in a jar with water covering about the bottom third. Use toothpicks pushed into the tuber horizontally to hold it at the right height - one end of the tuber submerged, the other end dry. Put it in a warm, sunny spot. Slips (shoots with leaves) emerge from the dry upper end in 4-6 weeks. When slips are 4-6 inches long, snap them off and root them in water for another week before transplanting.
The treatment problem: Grocery store sweet potatoes are commonly treated with a sprout inhibitor called CIPC (isopropyl N-3-chlorophenylcarbamate). A treated tuber simply will not sprout or will sprout very slowly with weak, low-vigor slips. NC State Extension’s sweet potato production program documents this issue and recommends sourcing from organic suppliers or certified seed potato producers for slip production (NC State Cooperative Extension, Sweet Potato Production, 2022).
Organic sweet potatoes are reliably untreated. At $1.50-3.00/lb for organic sweet potatoes versus $0.79-1.29/lb for conventional, you’re paying an extra $0.50-2.00 for a reliable outcome. Given that the alternative is waiting 6 weeks and getting nothing, it’s worth it.
Grocery store sweet potato slip production is viable and worth doing if you want to grow sweet potatoes. See the growing guide at sweet potato growing.
Celery: Kitchen Herb, Not Food Replacement
Celery (Apium graveolens) is one of the most widely promoted regrow projects online, and the claims are consistently overstated. The honest version: the inner stalks and leaves that regrow from a celery base are small, thin, and largely useful as a flavoring herb, not as a replacement for the grocery store head you started with.
Place the celery base (the cut bottom 2-3 inches of the head) in a shallow dish with about an inch of water. New growth emerges from the center in 5-7 days. Over 2-4 weeks you’ll get several sets of small, pale-green inner stalks and a significant amount of leafy tops. After 3-4 weeks the plant needs to go into soil or the growth stalls.
What you actually get: The inner stalks that regrow are much smaller than grocery store celery. A celery head retails at $1.79-2.49 (USDA AMS retail produce data, 2024). The regrowth from that base produces, at most, $0.50-1.00 in equivalent celery value - and that’s generous. Most of the weight is in the leaves, not the stalks.
The appropriate framing is: you’re extending the usefulness of the celery you already bought, not replacing your grocery purchase. The regrown celery leaves are excellent in stock, soup, and potato salad. The small interior stalks work fine for cooking applications where celery is a background ingredient rather than a feature. If you would have composted the base anyway, this is a low-effort way to get another few weeks of kitchen use from it.
Romaine Lettuce: Compost Avoidance
Romaine (Lactuca sativa var. longifolia) regrowing is genuine - the base does produce new leaves. The value is minimal. USDA data shows that lettuce regrowth from cut bases produces leaf mass at roughly 10-20% of the original head weight, and the leaves are from the interior of the head where light exposure was limited, meaning they’re paler and milder than the outer leaves you already ate (USDA Agricultural Research Service, Lettuce Postharvest Studies, 2019).
A full romaine head retails around $1.49-2.49. The regrowth, generously, produces $0.20-0.40 in leaf mass over 1-2 weeks before the base starts to deteriorate or bolt. The growth stops when the remaining stalk is depleted of stored nutrients.
Worth doing if you’re going to throw the base away anyway. Not worth planning around as a food production strategy.
Herb Cuttings: High Value, Covered in Detail Elsewhere
Basil (Ocimum basilicum) and mint (Mentha spp.) are excellent propagation candidates, but the mechanics and economics belong to a different category: you’re not regrowing scraps, you’re propagating from a living plant to create new plants. One $3 nursery pot of basil, stripped of cuttings and given 7-10 days in water, can yield 8-12 rooted cuttings, each of which grows into a full plant. At $3/transplant retail, that’s $24-36 in plant value from a single purchase.
The full treatment - including success rates by herb, timing, rooting hormone use, and a 5-year break-even analysis - is at herb propagation from cuttings.
What Doesn’t Work
Avocado pits: Yes, they’ll sprout into an attractive houseplant. No, they will not produce avocados in a temperate climate. Avocados from seed in the continental US require many years to reach fruiting age and are too cold-sensitive to survive outdoors north of Zone 9-10. Treat it as a houseplant propagation project if you enjoy the process.
Grocery store garlic: Grocery store garlic is almost always softneck varieties treated to suppress sprouting, and they’re often imported and may carry pathogens inadvisable for your garden soil. Seed garlic from reputable suppliers (certified disease-free) costs $1-3/head and is worth using. The difference in success rate is substantial.
Store-bought potato eyes: Similar issue. Grocery store potatoes are commonly treated with sprout inhibitors and are not certified seed stock. Planting them risks introducing late blight (Phytophthora infestans) or other soil diseases to your garden. Certified seed potatoes cost $5-15 for enough to plant a meaningful row and have been inspected for disease. The regrow-from-grocery approach isn’t worth the disease risk.
ROI Summary: All Methods Compared
| Crop | Input cost | Timeline | Yield estimate | Estimated gross value | Net value | Category |
|---|---|---|---|---|---|---|
| Scallions (4-jar rotation) | $5-6 initial | 7-10 days/cycle | 12-16 additional bunches | $17-22 | $11-17 | High value |
| Ginger (one rhizome piece) | $0.75-1.50 | 7-9 months | 1-2 lbs fresh rhizome | $3-14 | $1.50-13 | High value |
| Turmeric (one rhizome piece) | $0.50-1.50 | 7-9 months | 1-1.5 lbs fresh rhizome | $8-22 | $6.50-21 | High value |
| Sweet potato slips (organic, 1 tuber) | $1.50-3.00 | 4-6 weeks to slips | 8-12 slips | $2-6 in avoided slip cost | $0-4.50 | Moderate value |
| Celery base | $0 (from existing purchase) | 2-4 weeks | Small stalks + leaves | $0.50-1.00 | $0.50-1.00 | Kitchen herb use |
| Romaine base | $0 (from existing purchase) | 1-2 weeks | Small inner leaves | $0.20-0.40 | $0.20-0.40 | Compost avoidance |
Sources for retail prices: USDA AMS Retail Produce Price Data (2024); USDA AMS Specialty Crops Terminal Market Reports (2024); NC State Cooperative Extension, Sweet Potato Production (2022).
Practical Setup
The highest-ROI approach combines all three reliable methods at once: a 4-jar scallion rotation on the kitchen counter, one or two ginger rhizomes and one turmeric rhizome starting in containers in late spring, and basil cuttings propagating in water during the summer. The scallion jars take 2 minutes of maintenance per week. The containers take no more time than any other potted plant. The basil cuttings take about 5 minutes to set up and monitor.
Total ongoing effort: under 20 minutes per week. Total annual value, realistically: $60-100 from scallions, $20-40 from ginger and turmeric, assuming you cook regularly with these ingredients. If you don’t cook with ginger and turmeric, they’re not worth your container space. If you do, they’re probably the best per-square-foot return of anything you grow at home.
The celery and romaine regrowing is worth doing because you’re spending zero incremental effort on something you’d otherwise throw away. Just don’t count it in your food production budget.