Mason Jar Nasturtiums: Humidity Control for Succession Planting

Why Nasturtium Does So Well with Succession Planting

Okay, so picture this: it’s January, cold and grey here in Brooklyn, and I’m already itching for some fresh green. Every year, around this time, I get messages from folks asking me what’s the easiest, most rewarding thing they can grow indoors right now. And almost always, my answer is nasturtiums. Why? Because they're tough, they're beautiful, and honestly, they just make you feel like a rockstar gardener even if you’ve killed a cactus or two. Plus, those peppery leaves and vibrant flowers? Edible! Straight into your salad or garnishing a fancy cocktail. You gotta love that.

Nasturtiums are fantastic for succession planting, especially in a compact space like a mason jar. It means you're not just planting one batch and calling it a day. Nope. You're constantly sowing new seeds every week or so, ensuring a steady supply of fresh leaves and flowers. It’s like having a tiny, perpetual nasturtium factory on your windowsill. I've written a whole post about succession planting for continuous harvest all season, and it totally applies here, even on a micro-scale.

The beauty of nasturtiums for this method is their relatively quick growth cycle. From seed to edible leaves can be as little as three to four weeks, sometimes even less if you hit all the right notes. This rapid turnaround is key for succession – plant a new jar, and by the time you're finishing up the last one, the next is ready to start producing. It’s glorious.

What You'll Actually Need

You don't need a ton of fancy gear for this, which is part of its charm. Keep it simple, folks.

• Mason Jars: About a quart-sized jar is perfect. Wide-mouth is easier to work with, trust me. You can grab these at any grocery store or hardware store. I pick up packs of six whenever they're on sale.
• Nasturtium Seeds: Any variety will do, but I'm partial to 'Jewel Mix' for its range of colors, or 'Alaska Variegated' if you want some snazzy foliage. Eden Brothers usually has a great selection.
• Potting Mix: This is where I might get a little opinionated. I swear by FoxFarm Ocean Forest for starting mixes. It's got a good balance of aeration and nutrients, and it drains beautifully. You want something light and well-draining, not heavy garden soil.
• Trowel or old spoon: For scooping soil.
• Watering Can (small): A bottle with a small spout works too. Precision helps.
• Plastic Wrap or dome: This is crucial for your mason jar nasturtium humidity control in the early stages.
• Grow Light (optional but recommended): A basic LED grow light is a game-changer, especially in winter. Last March, my first Nasturtium batch in a mason jar got super leggy because I basically skimped on adequate light – lesson learned the hard way. They stretched and looked pathetic. Now, I always set them under a simple grow light for 12-14 hours.

The Growing Process, Step by Step

Let's break this down into digestible chunks. Remember, we’re aiming for 3-4 weeks from seed to harvest here, and you'll be starting a new jar every 7-10 days.

Week 1: Sowing and Sprouting

1. Prep Your Jar: Make sure your mason jar is clean. Fill it about 3/4 full with your potting mix. Don't compact it too much; you want it airy.
2. Planting the Seeds: Nasturtium seeds are pretty big, so you can plant them individually. I usually put 3-4 seeds in one jar, just in case one or two are duds. Plant them about half an inch deep.
3. Watering In: Gently water the soil until it’s evenly moist. You don’t want it soaking wet, just consistently damp.
4. The Humidity Dome: This is where your mason jar nasturtium humidity control comes in. Cover the top of the jar tightly with plastic wrap. You can poke a few tiny holes in it with a toothpick, but not too many. This traps humidity and creates a mini-greenhouse effect, which nasturtium seeds absolutely love for germination. This is particularly important if your indoor air is dry, which it usually is during winter.
5. Warmth and Light: Place your jar in a warm spot, ideally around 70-75°F (21-24°C). A heat mat isn't necessary but can speed things up. If you have a grow light, put it under there immediately. Even before they sprout, light can help. I'm talking one of those clip-on LED lights you can grab for twenty bucks.
6. Check Daily: Keep an eye on the moisture. If the soil surface looks dry, mist it lightly. You'll usually see sprouts within 5-10 days.

Week 2: Young Seedlings Emerge

6. Remove the Dome (Partially): Once you see those first little green shoots poking through, it's time to start acclimatizing them. Remove the plastic wrap for a few hours during the day, then put it back on at night. Do this for 2-3 days. This gradual reduction of humidity helps them adjust to your home's regular air. You don't want to shock them by just yanking it off.
7. Thinning (if needed): If all your seeds sprouted, you’ll have a few seedlings. Pick the two strongest looking ones and gently snip off the others at the soil line with small scissors. You want to avoid pulling them out, as that can disturb the roots of the ones you want to keep. One or two plants per quart jar is plenty.
8. Consistent Light: Make sure they're getting plenty of light. If you’re using a grow light, keep it about 4-6 inches above the tops of the seedlings. Without enough light, they get leggy and weak. Trust me on this.
9. Watering Rhythm: At this stage, let the top half-inch of soil dry out slightly before watering again. You're trying to prevent damping off, a fungal disease that thrives in overly wet conditions.

Week 3-4: Growth and Preparing for Harvest

10. Full Humidity Removal: By now, your nasturtiums should be sturdy enough to handle ambient humidity. Ditch the plastic wrap completely. Continued mason jar nasturtium humidity control is less about creating a humid environment and more about ensuring good air circulation to prevent mold and mildew.
11. Feeding (Lightly): If your potting mix didn't have much fertilizer, you can start with a very diluted liquid feed. I usually go with a half-strength organic fish emulsion or some FoxFarm Grow Big, once every two weeks. Nasturtiums don't need a ton of food, especially in a small container. Too much nitrogen, and you'll get all leaves and no flowers, which is fine if that's what you're after.
12. Watch for Pests: Indoor plants, even in mason jars, can attract pests. Keep an eye out for aphids, especially under the leaves. A quick spray of insecticidal soap (Dr. Bronner's castile soap mixed with water works in a pinch) usually deals with them.
13. Harvesting Begins: Around week 3-4, you should have leaves big enough to start snipping. Don't be shy! Harvesting actually encourages the plant to produce more.

Mistakes I've Made (So You Don't Have To)

Oh, the stories I could tell. I mentioned the leggy nasturtiums because I was too lazy to set up a grow light. That batch ended up in the compost. Another time, early on, I tried to grow a ton of nasturtiums in a single small jar, thinking more plants equaled more harvest. Nope. They just competed for resources, got stunted, and turned yellow. Less is more in a tiny environment. Thin those seedlings, people!

And let's talk about overwatering. My first attempts at growing nasturtium in tin cans suffered from my enthusiasm with the watering can. The soil stayed perpetually soggy, and the roots just threw up their hands (or roots, I guess) and rotted. Learn to lift the jar; if it feels super light, it needs water. If it still feels heavy, hold off. It's a simple trick, but it works.

Little Things That Make a Big Difference

• Air Circulation: Even after the dome comes off, ensuring good airflow around your jars is important. Stagnant air can lead to mold issues, especially around the soil surface.
• Water Quality: If your tap water is heavily chlorinated, let it sit out overnight before using it. The chlorine will dissipate. Or, use filtered water.
• Fertilizer for Flowers: If you really want those beautiful flowers, once your plant has a few sets of true leaves, switch to a fertilizer higher in phosphorus, like a bloom booster. I even wrote about fertilizing nasturtiums in buckets for bigger yields, and the principles still hold for mason jars, just in smaller doses!
• Soil-Blocking (Advanced Tip): For future succession planting, consider starting seeds in soil blocks before transitioning them to jars. It reduces transplant shock. Something I talk about a lot in my posts about soil-free strawberries in totes.

When to Harvest and What to Expect

You can start harvesting individual nasturtium leaves when they're about the size of a quarter. Just snip them off at the base of the stem. Don't take more than about 30% of the plant at once, especially in the early stages, otherwise, you'll stress it out too much. For harvesting flowers, let them fully open and then snip them. They'll have that lovely peppery flavor, perfect for salads, pestos, or just eating straight off the plant.

With good mason jar nasturtium humidity control during germination and consistent care, each jar can produce for several weeks. Once a jar starts looking tired – fewer new leaves, yellowing foliage, or just generally looking lackluster – it's time to compost it and start fresh. Because you've been succession planting, you'll already have the next batch coming up hot, ready to take its place. This is what it's all about, continuous fresh greens without needing a massive garden. Pretty sweet, right?