Sorry, Greenhouses – These Seeds Actually Grow Better Sown Outside

TikTok creator @emjorealdavies recently shared a video in which she pushed back on one of gardening's most persistent and frankly annoying assumptions: that a greenhouse is the key to growing successfully from seed. Her video makes a compelling case and features several flower varieties that do well when sown directly outside.

She mentioned several of her favorite varieties that don’t require a greenhouse, including sweet peas, calendula, ammi majus, nasturtiums, strawflowers, and snapdragons, all sown into the ground with some very impressive results. It turns out she’s actually onto something that experienced gardeners have known for a long time: you don't need to start everything in a greenhouse. And, of course, I also had to consult a few experts on the matter.

Why Some Seeds Prefer the Ground

While it’s understandable that many gardeners assume growing seeds in a greenhouse will give them a head start, the idea doesn’t necessarily hold up for every single variety. The reality is much more nuanced, and it all comes down to the biology of the seed itself.

James Smith, product marketing manager at Rural Supplies, explains the underlying science clearly. "Plants with taproots or brittle root systems simply don't recover well once disturbed. Direct sowing avoids that pause and allows uninterrupted root development so you get a better finished result.”

A fine mesh cloche (like this one on Amazon) is worth using to protect your newly germinated seedlings from slugs and pests during that vulnerable early stage without needing chemicals.

Sweet peas, for instance, develop a deep taproot quickly after germination. This is exactly why they are going to hate you for moving them from their cozy module; it's best to sow them where they will grow.

While you may need to plant some of your seeds outside, they still need water, but you don't want to drown them. A rosehead watering can is perfect for delicate, precise watering, like this one from Jorzer (available on Amazon).

Staci Hill, co-author of The Preserver's Garden and co-founder of Gooseberry Bridge Farm, agrees. "Things that germinate and grow quickly and don't like root disturbance tend to do the best outside," she says. This fast-germinating logic applies to several of the flowers in @emjorealdavies' video: nasturtiums, calendula, and ammi majus all germinate rapidly in open ground and will gain almost nothing from time spent in a module on your windowsill.

Strawflowers and snapdragons are similarly resilient, and in the case of snapdragons, exposure to cooler outdoor temperatures can actually improve flowering.

What the Greenhouse Is Actually Good For

I’m definitely not bashing greenhouses, and they absolutely have a place in the garden. The experts are all in agreement on which plants get a genuine benefit from being started indoors: slow-growing, heat-loving varieties with fibrous root systems that can tolerate transplanting and need a longer season to produce.

Hill explains that the decision isn't always black and white. "Your climate and season length determine if you should start seeds ahead of time or direct sow them outdoors," she says. "The main factor is that of the specific requirements for the seeds. For example, tomatoes need more warmth to germinate, warmer nighttime temperatures, and longer daylight hours to do well – where lettuce can germinate in cooler soils and grow with less light and less warm conditions thereafter. Every plant is like that."

If planting several seeds at once, as most people tend to do, this seed dibber from Amazon can make 6 holes at once, saving you time and energy.

Winter-Sowing As An Alternative

For those who want a middle ground, she also recommends winter sowing: "Another option to try is more in-between indoor and outdoor called winter sowing, where you start the plants inside a mini greenhouse made out of a milk jug – this works great for things like cool weather veggies, herbs, and perennial flowers."

Smith offers a useful rule of thumb for deciding which side of the line any seed falls on: "If it resists root disturbance or doesn't need a long season, sow it where it's going to grow."

The TikTok creator's point stands up under the heat of scrutiny. For a surprisingly long list of seeds – including some of the most popular flowers in a cutting garden – the ground itself is the best place to start.