How to “Brush” Your Seedlings For Stronger Stems
Brushing seedlings may seem like extra work, but it’s a valuable practice for growing strong, resilient plants. Though they have protection indoors, they lack exposure to natural conditions like wind, rain, and temperature shifts. Join seasoned gardener Jerad Bryant and learn how to use this practice for healthy, robust specimens.
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“Brushing” is another term for rubbing or dusting seedlings. Outdoor plants must resist external factors like wind and rain. They grow strong in response to these stimuli, creating more roots or thicker stems that resist these pressures. Indoors, your seedlings lack wind and rain exposure. They may grow spindly, leggy, or weak instead of robust.
Though brushing seems unnecessary, studies show it creates compact plants with short stems. This is great for indoor seed starting, as it means you can limit your crops’ growth until you’re ready to plant them. Brush them daily and they’ll form a small, strong structure perfect for transplanting.
Why Brush Seedlings?
If your seedlings grow leggy every year, brushing is an excellent way to create dense plants with little effort or supplies. You don’t need hormones, pruners, or fancy chemicals. You simply need a piece of paper, your hand, and some growing plants.
Brushing helps combat legginess and encourages short shoots with small internodes. This is great for indoor starts, as they’ll adapt to outdoor conditions better than spindly, unbrushed ones. Leggy young plants are susceptible to breakage when wind blows past them, whereas short, squat ones resist external pressures.
Brushing helps your plants adapt to the outdoors during the hardening-off period, but it’s also a great way to prolong the growing season for commercial growers. You can grow the starts as long as you need in the greenhouse—their short height makes them easy to care for. Then, when the plants’ most popular season rolls along, you’ll have potted specimens ready to sell.
How to Brush Seedlings
Brush your tender plants so they grow strong and hardy. These six steps guide you through the process, from seed germination to transplanting.
Step 1: Germinate Seeds
To brush, you first need seedlings! Shrubby plants with erect stems are the best to brush, though you can do so with any type you’d like. Peppers, tomatoes, and cabbage are excellent vegetables for this method, while sage, oregano, and thyme are great herbs to brush.
After picking your species, sow their seeds in pots indoors. Outdoor specimens don’t benefit from brushing as much as indoor ones, as they have wind and other natural factors to respond to. This strengthening method is best for indoor potted plants.
Keep the seeds moist until they germinate—most species sprout after a week or two, though some can take a month or longer. Consult guides for the specific types you’re growing so you know how long to wait.
During the sprouting process, consider using humidity domes or heat mats to create the perfect conditions for germination. Most seeds require consistent moisture to sprout; humidity domes trap moisture and lead to high sprouting rates. Heat mats boost soil temperatures within the optimal range. Remove humidity domes and heat mats after successful germination to avoid overheating or overwatering the young specimens.
Step 2: Wait for True Leaves
Tiny seedlings don’t like brushing; they’re too weak to handle it. They may break or snap when you rub them! It’s best to let your plants grow true leaves first before treating them.
Sprouting specimens have two types of leaves: cotyledons and true leaves. Cotyledons are the first to emerge; they look different than mature leaves of the same species. They’re often oval and oblong. Some species have two cotyledons, while others, like onions, have one.
True leaves emerge after the cotyledons. They resemble mature leaves of the species and grow all along the stem. While true leaves persist throughout the growing season, cotyledons fade after the plant matures into adulthood. Your crops are ready for brushing once their first two true leaves appear.
Step 3: Gather Brushing Materials
So, what should you rub your young crops with? Paper, plastic, and cloth are all excellent materials for brushing. You want light objects that won’t break or snap plant stems. The goal is to roughen up your specimens without hurting them.
I like to use paper sheets. They’re readily available and gentle on tender stems. Whether you use plastic, cloth, or paper, the process for using these materials is similar. Use whichever type is cheap, sustainable, and easy to source.
You can use your hands after a few weeks of using secondary materials. Your hands are the perfect tools once the squat specimens are strong and hardy. Avoid using your hands if the specimens have two or fewer true leaves or are weak and spindly.
Step 4: Brush Seedlings
With all your materials in hand, you’re ready to start brushing your tender crops! Though commercial growers often have intricate, automatic setups that facilitate this action, it’s easy to do at home on your own.
Start by rubbing the sheet along the seedlings, gently pulling it so they push down and bounce back up. The process is the same with plastic, cloth, or paper sheets—rub them along your crops so they touch their tops and softly push them.
Do this daily for the best results. It simulates daily wind flow that would occur naturally outdoors. You no longer need to brush young specimens once you move them outside, as they’ll have access to normal airflow.
Step 5: Blow On Seedlings
Rather than rubbing young specimens, you can blow on them! Blowing air is more akin to natural airflow, as it more closely simulates what garden species undergo outside than brushing would. Simply position your mouth near the propagules, gently blow on them, and repeat once or twice a day.
If you don’t have time to blow air daily, you can set up a fan on low near your propagation station. Fans are the best way to simulate wind from the outdoors. They blow steady, consistent air streams that toughen up young specimens. The stems then grow thick in response to the stimulus so they can resist the persistent push of the fan.
Fans may be too strong for small crops. Their thin, spindly stems may snap or crack! Set the fan near the propagation station first, then gradually expose the plants to stronger airflow as they mature. Note that fans can dry the soil quickly. Ensure it stays sufficiently moist throughout the growing period.
Step 6: Transplant Mature Specimens
As spring and summer arrive, the time to transplant grows near! You want to transplant brushed specimens before they outgrow their containers. If they outgrow their containers, you’ll need to up-pot them into larger containers and continue brushing them.
The key to a successful transplant is the hardening-off process. Though brushed seedlings transplant well compared to unbrushed ones, they still need some care to perform their best. Gradually expose them to cold or hot outdoor environments, setting them out for a few hours and bringing them inside at night.
Progressively leave the specimens out longer each day until they’re outside all day and night. After a two-week hardening off period, you’re crops are ready for transplanting. Remove them from their containers, set their rootballs in holes, and backfill soil until they’re secure in their new homes. If you’re curious, you can learn more about transplanting seedlings in this easy-to-follow guide.
