How to Grow Zucchini Indoors
A zucchini has more potassium than a banana! They are fairly recent to the US – bring brought over from Italy in the 1920s.
Sprouts in 1-2 weeks. Harvest from Month 3+ on.
Equivalent of 7+ hours of direct sun [DLI of 21+ mol/m²/day].
Intermediate. You’ll sprout, thin, prune, and pollinate.
Best Zucchini varieties to grow inside.
Zucchini has two types: vining and bush. Bush types are more suited to grow indoors than vining ones. We’ve listed the most popular varieties for you below:
Perfect for smaller gardens and containers on the patio. Delicious when steamed or stir-fried.Totally Tomato
Has a delicate, nutty flavor, which shines through when steamed, sauteed, or stir-fried.West Coast Seeds
Has bright, beautiful yellow skin. Perfect when eaten while still under 8 inches.Amazon
Delicious steamed or sliced lengthwise and grilled on the barbecue.Amazon
Best Setup for Zucchini Plants
Ceramic Self Watering Planter (preferred) or pot that is at least 12″ / 5 gal.
Standard Potting Mix
Herb Blend. This should be high in nitrogen (with NPK numbers like 10-5-5).
A strong grow light that can give the equivalent of 7+ hours of direct sun [DLI of 21+ mol/m²/day].
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Preparing your Planter & Watering Schedule for Zucchini
Zucchini plants do well in moist soil conditions. If the soil dries out completely the roots will die back and it will be tough for the plant to recover. On the other hand, if the roots are exposed to standing water for too long, they can rot.
A Ceramic Self Watering Planter filled with a standard potting mix self-regulates to keep the soil at consistent moisture for your plant to thrive (and no watering guesswork for you).
To set one up:
- Fill up the planter with dry soil from the bag, gently tamping down the top.
- Dump the soil into a large mixing bowl and add water until the soil is moist, but not sopping wet (about ½ Cup)
- Mix in 1 tablespoon of the Herb Blend Plant Food.
If you are using a regular pot instead, it should be a little bit bigger (at least 12″ / 5 gal and will need drainage holes to prevent it from being over watered. Let the top of the soil dry out between watering.
Starting your Zucchini: Seed vs Propagate
Zucchini plants are best to start from seed in the area they will grow to their full size (known as “direct sowing”). They’re not practical to propagate from cuttings & they don’t handle transplanting well. Fortunately starting from seed is simple and they sprout quickly!
How to Plant Zucchini seeds
Zucchini grows quickly from seed. Plant 1 site in a 12″ / 5 gal container. In larger containers, space sites 24″ apart. For each site, plant 2 seeds 1″ deep. Keep the soil warm ( 68-95°F, ideally 70°F). Sprouts typically appear in 10 days but can be as quick as 7 days or as long as 14 days depending on your conditions.
Why starting Zucchini doesn’t make sense
Zucchini are short-lived plants and prone to root rot. Even under perfect conditions, they lack the genetic makeup to readily produce roots from their stems.
Where to grow your Zucchini plants
Zucchini plants have the highest light needs of any plant – so unless you have a totally unobstructed southern-facing window and plan on only growing in the summer – you’ll need a grow light. We still recommend taking advantage of your bright window (sunlight is free and great for plants!) and supplement it with a grow light. For an introduction to grow lights, head over to our post on grow lights for indoor gardeners. We’ve also got a buying guide for screw in types, but to keep things simple in this guide, we’ll just provide directions for the 24W Screw in Bulb by Sansi, which we think is a good middle-of-the-road option.
How bright should your grow light be?
Zucchini plants need the equivalent of 7+ hours of direct sunlight [DLI of 21+ mol/m²/day] to grow their best. In order to provide an equivalent amount with a grow light, it needs to be pretty bright! The 24W Sansi bulb should be placed 6 inches away from the top of the plant. This will give your PPFD (the standard measure of brightness) of 500 μmol/m²/s.
How many hours per day do your Zucchini plants need under a grow light?
Zucchini plants are what’s known as “day-neutral” so can grow under a range of daylight lengths. In order for them to get enough light, we recommend setting up a timer to leave it on for 14+ hours per day.
Zucchini Plants Grow Faster in Warmer Temps
Zucchini plants are called “warm-weather crops” and like temperatures right around 70. They will grow fine in conditions between 60 and 100°F but can lose their fruit if it drops below 40. On the other hand, if they are too hot, they will drop their blossoms, wilt, and stop ripening. Most homes are in a good range – and a south-facing sunny window can help get a plant the extra heat if needed.
Week 1-2: Check for Sprouts
You could see seedlings in as little as 7 days (though 10 days is more typical). If it’s been 14 days and you still don’t have any sprouts, it’s likely that your setup is too cold.
Week 3: Thin Your Seedlings
Thin your planter to only have 1 seedling per site – leaving the largest plant. If you are using the reccomended planter (at least 12″ / 5 gals) this will mean you’ve got 1 plant after thinning. By getting rid of the smaller seedlings, you’re allowing the biggest and strongest one to flourish by reducing its competition for water, food, and space.
If your seedlings are under 2 inches, stretching out, or folding over, it’s likely that they don’t have quite enough light.
Week 4: How to Prune & Trellis Zucchini Plants
Zucchini plants are vines that will continue to grow and grow – so a monthly trim will be a necessary part of your care routine. You’ll make your first cut at about the second month, or when you have 5 branches and a growing tip, cut (or just pinch) off the main stem above the 5th branch. By removing the growing tip, you’re having the plant focus its energy on those 5 branches. There are several support options, ranging from cages to stakes, but we like to train those 5 branches up a fan trellis with plant clips.
After this, pruning and trellising is more of an art (fortunately an art that’s hard to mess up) but the general things you’ll want to look of for when:
- Little leaves grow out of the “V” where a branch meets the main stem. Snap these “suckers” off right at their base.
- The main stem is going past your grow area. Pinch of the growth tip where you want it to stop.
- A heavy cluster of Zucchini starts to form. The weight can snap the vine, so clip right above the cluster to the trellis to avoid this (mildly heartbreaking) event.
- The plant is getting so dense that light and air can’t get in. Keep up with interior pruning to have a tidy “bonsai” Zucchini plant.
Month 2+: How to Pollinate Your Zucchini Flowers
We only recommend self-pollinating Zucchini, because it’s a bit of a pain to pollinate them otherwise (you would need to find a “male” and “female” flower that would have happened to open at the same time). Assuming you are using one of the self-pollinating varieties – wait until the flowers open then just give them a slight shake or “rub the nose” of the flower.
Month 3+: How to Harvest Zucchinis
The rule for these is to “pick um often and pick um all.” Zucchini are at peak crispness for a short time, so you need to pick often to catch the small window of the best flavor. When vegetables start to form it’s helpful to experiment a bit to find out what they are like at peak flavor for you. If you miss a single Zucchini (and they’re good at hiding!) and it grows to maturity then these plants end its life cycle early. By preventing the plant from finishing that last step of making seeds, you are able to keep it producing vegetables for much longer.
Month 6+: End of Life
Indoor Zucchini plants can last for up to half a year, but eventually, they’ll tire out. Once you seed a big drop in productivity, in spite of giving it sufficient plant food it’s time to start over.
Shop This Blog
The right supplies can take the guesswork out of caring for your plants – and turn care from a daily to weekly routine. Through our grow tests, we’ve found these products to produce the best indoor Zucchini (and also have simple maintenance). Plants are adaptable and can grow in many different conditions, so they are by no means necessary if you already have other supplies.
Best Containers for Zucchini: Ceramic Self Watering Planters
Plants thrive on consistent moisture but can suffer if they’re waterlogged. A semi-porous ceramic self regulates ideal conditions. Our favorite is the COSWIP planter. Runner up is XS Self Watering Planter by Wet Pot.
Best Soil for Zucchini: Standard Potting Mix
Zucchini likes a rich and moist root zone – so you are best off with a standard potting mix – we like this Organic Mix by Espoma.
Best Nutrients for Zucchini: Herb & Lettuce Blend
Zucchini likes nutrients that are high in nitrogen (with NPK numbers like 10-5-5). For a Herb Blend, we recommend: Joyful Dirt All Purpose
Best Light for Zucchini: DIY or Soltech
There is a very small chance that you have the bright windows needed to grow these without a grow light. If you are looking for a higher-end option – we love the Aspect Light by Soltech. For a more affordable option, a DIY setup using a 24W Screw-in Bulb by Sansi with a Clamp Light and Mechanical Timer works well too. Check out our complete guide on a DIY setup for less than $40 or our buying guide for screw in bulbs.
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