April 14, 2026
4 min read
The cheapest way to start a balcony herb garden isn't to buy plants. It's to buy herbs you were going to buy anyway and turn the leftovers into plants.
Not every herb cooperates with this. Rosemary, thyme, and oregano can be done from cuttings but they're slow and finicky. Soft-stemmed herbs, though? They practically beg to root in water. Here are the three that work reliably on any sunny windowsill, including a warm Bay Area one.
1 Basil
BeginnerBuy: A bunch of fresh basil from the grocery store produce section. The kind that's still on the stem, not pre-torn leaves.
What to do
- Pick the freshest-looking stem with at least four inches of length.
- Pinch off the bottom leaves so the bottom two inches of stem are bare.
- Put it in a glass of water with just the bare stem submerged — leaves stay dry.
- Set it on a sunny windowsill. Change the water every 2–3 days.
- Roots should appear in 7–14 days. Wait until they're at least an inch long before potting.
Basil is the poster child for this technique because it's so aggressive about wanting to root. One bunch of grocery store basil can easily give you 3–4 cuttings, which means 3–4 free plants. In our climate, potted basil outside can produce from April through October without complaint.
2 Green Onions (Scallions)
BeginnerBuy: A bunch of green onions. You want the ones with visible white bulbs and intact roots, not trimmed-off roots.
What to do
- Use the green tops as you normally would in cooking.
- Keep the bottom two inches — the white bulb plus the root threads.
- Put those root-end-down in a shallow glass of water. About an inch of water is plenty.
- Sunny windowsill. Change the water every few days.
- New green tops start pushing up within days. You can keep cutting the tops indefinitely — the bulbs will keep regenerating.
This is honestly the easiest kitchen project I know. You'll see new green pushing up within 48 hours. Move them to a small pot of soil once the roots look established and you'll extend their productive life significantly — but the glass-of-water version works fine on its own for a month or two.
3 Mint
Beginner → EasyBuy: A bunch of fresh mint from the produce section, ideally the brightest-green, freshest-looking bunch you can find.
What to do
- Same as basil: pick healthy stems, strip the bottom leaves, put the bare stem in water.
- Mint roots faster than basil in my experience — you'll often see root nubs within 5–7 days.
- Once roots are an inch long, pot it. Use its own pot. Mint will take over anything you plant it with.
Serious warning: mint is a thug. Never plant mint in a pot with other herbs. It will outcompete and eventually smother anything sharing its root space. Always its own pot. Always.
Other than its territorial ambitions, mint is the most forgiving of the three. It handles partial shade, tolerates forgetting to water, and grows fast enough that you'll be giving cuttings away to neighbors within a few months.
If Your Windowsill Isn't Delivering
Not every apartment gets the kind of window that makes this easy. My own indoor collection runs mostly on grow lights — Barrina T5 strips and a few puck lights on 11-hour timers — and cuttings root just as well under artificial light as they do on a south-facing sill. If your windowsill isn't getting four or five bright hours a day, a cheap T5 strip parked about 8–12 inches above the jars will close the gap. You don't need a full rig. One cool-white strip over a kitchen counter is enough to keep rooting cuttings happy.
Why This Works
Soft-stemmed herbs like basil, mint, and scallions can produce adventitious roots — new roots that form directly from stem tissue — when the right conditions are met: moisture, warmth, light, and a stem node (the joint where leaves meet the stem) in contact with water. Grocery store herbs are usually cut just hours before you buy them, so the stem tissue is still very much alive and ready to regrow.
The same technique works on pothos, philodendron, tradescantia, and dozens of other houseplants. If you've ever wondered how plant people build a collection without spending much money, this is most of the answer.
A Note on Our Climate
Here in the Bay Area, once these rooted herbs move outside to a balcony pot, they're in business from April through October with minimal fuss. Mint can even overwinter outdoors in most of Santa Clara County. Basil won't — it's an annual and should be treated as one — but you can get five or six months of production from a $3 bunch of grocery basil, which is a pretty good return.
