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How to sow and grow zucchini

Our zucchini is one of the few species you can grow on a trellis. Perfect for growing in a garden box.

The plants produce a lot: from the beginning of July until the end of October you can harvest one zucchini after another.
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Climbing zucchini in August

What is a climbing zucchini?

Most zucchinis take up tons of space. They can take up around 9 square meters: too big for container growing.

A climbing zucchini has a long stem that you guide up a trellis. Since it grows upward - not outward - it takes up less space.

Zucchini is a summer squash. You can harvest them when the skin is still tender. Like pumpkins, they belong to the gourd (fruit) family.

Zucchinis originate from Mexico and the northern part of South America. Colonists brought the seeds to Europe, and today's zucchini was developed near Milan, Italy in the 19th century.

Is zucchini good for you?

Yes, you could say that. It contains a lot of potassium, which is good for your heart and blood vessels. It's also got vitamin B1, B2, B6, B11, and C in it. These vitamins are good for your metabolism and immune system.

The vitamin A and the antioxidants lutein and zeaxanthin are great for your eyes. And since zucchini is high in fiber - and has almost no carbs - it's also good for your waistline 😉
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Flowering zucchinis: also good for bees

More about our climbing zucchini

This zucchini was developed for professional growers: the plants are compact, grow up a trellis, and produce a lot. Zucchinis grow well in a cold greenhouse, but they also do well outside in mild summers.

The zucchini is a real summer vegetable and can't stand the cold. Since the seeds germinate at 20 - 25 °C, sow them indoors first. You can move them outside at the end of May.
  • Species name: Black Forest F1
  • Family: fruit
  • Plants per square patch: 1
  • Height: up to 200 cm
  • Sowing: from end of April to end of May
  • Germination: between 20 and 25°C in 4 to 10 days
  • Time to harvest: from 9 to 10 weeks
  • Sunlight: needs a sunny spot
Want to buy climbing zucchini seeds? We sell them in individual seed bags, or you can find them in our climbing vegetable seed pack:

What do you need to grow your own zucchini?

Just this:
  • a 30x30 cm patch with airy, nutrient-rich soil mix
  • climbing zucchini seeds
  • a place with at least 8 hours of sunlight a day
  • a trellis or something similar to guide the plants upwards
In other words: an MM-Mini, or a square patch in a garden box, an MM-Klimrek trellis, and MM-Mix.

Growing your own zucchini in MM-Mix is super easy. If you use poor-quality (potting) soil, it's much harder and the results will be disappointing. So just go for the best.
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Climbing zucchini in a Planty Garden

How do you sow and grow climbing zucchini?

This zucchini variety is included in the free Planty Gardening app. Use it, and you'll get step-by-step guidance from seed to harvest.

Each vegetable goes through a number of stages - we call them levels. The app tells you exactly what to do at each level and checks in when your plants are ready for the next.

So you don't need to know how to grow zucchini before you start: the app takes you through every step.

But if you'd like to read more about those steps, here's what the process looks like:

Level 1: Pre-sowing zucchini - pre-germinating seeds

Zucchinis are real summer vegetables. The seeds only germinate above 20°C, any lower and they won't sprout.

So, sow them indoors around the end of April/beginning of May. That's called pre-sowing. When the plant is big enough, you can move it into your garden box at the end of May.

Or - since the plants grow so fast - you can also pre-sow them at the end of May. Then you can move it outside sooner.

There's one step before you pre-sow: let them grow a root first. That's called pre-germination or pre-sprouting.

If you pre-sprout your seeds you can be sure your seedlings will grow well. And you want to be sure: these zucchini seeds aren't cheap. Why risk it? 😉

Here's how to pre-sprout: get a piece of paper towel moist, fold it in half, put the seeds in between the 2 layers, and you're done.

Check every now and then for a root. Sometimes it takes 2-3 days, often a little longer. Some seeds even take more than 10 days.
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Germinating climbing zucchini seeds

Level 2: Put the pre-sprouted seeds in pots

Next, you're ready to pre-sow. Here's what you need:
Fill the 2 air pots with equal parts vermiculite and MM-Mix.

This half-half mixture is ideal because seedlings don't need a lot of nutrients yet. The MM-Mix alone is too rich. Too many nutrients and they'll grow too fast: the plants become limp instead of sturdy. The vermiculite also helps retain moisture.

So, make the mixture nice and damp. Put 1 seed in each air pot. Be careful: you don't want the root to break off.

Then put the pot in a bowl or saucer, give it some water, and put it in a warm place on the windowsill.

That's it.

Level 3: Zucchini seedlings

When you see the first seedlings, it's time for the next level. Put the air pots in the lightest spot you have, but ideally not too warm.

Give the air pots a quarter turn every day to prevent the seedlings from growing crooked. Keep the mix moist.

In 5 days or so they'll be ready for the next level.
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Level 4 and 5: Taking care of your plants on the windowsill

Keeping plants happy on the windowsill is tricky. Make sure they get plenty of light and are not too warm. So, full sun, but not warmer than 20°C.

Give the pots a quarter turn every day to prevent crooked plants, and keep the mix moist.

Level 6-10: Getting used to the outdoors

Around the end of May, let the plants get used to the outside air: a little longer every day. 

At level 10, your plants spend all day outside and only come inside at night.
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Level 11: Plant the most beautiful zucchini plant

Once your plant has acclimatized to the outdoors, choose the most beautiful one and transfer it to your garden box. Choose a patch in the back row near the trellis.

Make a hole, sprinkle some MM-Plantfood in it, and put the plant inside.
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Zucchini planted on a trellis

Level 12 and 13: Care and the trellis

For these levels, it probably won't be very warm and the plant won't grow that fast. Just make sure it grows upward and not sideways. If necessary, put a stick next to it to guide it in the direction of the trellis. 

A climbing zucchini won't grab onto the trellis on its own, so tie it up with string, plant clamps, or binders.

Water your zucchini plant every day if the weather is dry.
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Guide your climbing zucchini up the trellis

Level 14: Flowering and fertilizing

Your plant will start to flower soon. Zucchinis have both male and female flowers: the male ones have a thin stem and the female ones have a thick bump under the flower bud - that's where the zucchini fruit grows.
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Left: female flower. Right: male
Bees and bumblebees fertilize the female flowers with pollen from the male flowers.

If they don't, your small zucchini will fall off before it really starts to grow. (Same thing happens to pumpkins.)

Unfortunately, there are fewer and fewer bees these days. So, go ahead and take pollination into your own hands:
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Stamen of the male zucchini flower
Male flowers usually bloom first. As soon as a female flower blooms, pick a male flower and remove the petals.

Rub the large stamen (sorry, I don't know any other word for it) along the pistil of the female flower.

That's it: the flower is pollinated and the zucchini can start growing. And you can throw the edible petals in a salad or smoothie: delicious.
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Fertilizing zucchinis flowers by hand

The next levels: Harvesting

If the weather's nice, you'll harvest your first zucchinis at the beginning of July. Using scissors is the best way to do it.

What do you use zucchinis for?

You can cook all kinds of things with zucchini. Boil them briefly, stir fry them, grill them on the barbecue, add them to omelets or pasta sauces in small cubes, or make them into soup.

Zucchinis are great cubed in salads as a raw, just like the flowers.

Or use them as a pizza topping, like Manja does:
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Pizza with zucchini

Add growth and nutrients

As soon as the first zucchini appears, sprinkle some extra nutrients (MM-Plantfood) at the base of the plant. Do this again every 4 to 5 weeks.

Zucchini plants grow pretty tall: they can reach up to 2 meters during hot summers or in a greenhouse. Tie them to the trellis regularly to keep them stable.

You can harvest until the first frost - or a little longer if you protect your plants with a crop cover.
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Spoonful of MM-Plantfood every 4-5 weeks

Growing issues

Getting zucchinis started can be a little tricky, especially if it's still chilly when you put them outside. But once they catch on, not much can go wrong.

Sometimes zucchinis can fall off the plant when they're still small: it's either because they weren't fertilized or they aren't getting enough nutrients.

Read more about that here.

You can pretty much expect mildew when the fall starts. It's easy to manage though.

So, what's stopping you from growing your own zucchini?

Our zucchinis are delicious and fun to grow.

Plus: with our app and materials, it's almost impossible to fail 😉

Buy your zucchini seeds here or get started with a complete starter kit:
Have fun!
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