Onosma erecta

Hello fellow plant lovers! Today, I want to talk about a plant that, in my opinion, doesn’t get enough love: Onosma erecta. You might know it as Sacred Tooth or Heavenly Trumpets, and for good reason. Its delicate, bell-shaped flowers, often in vibrant hues of pink, purple, or white, hang gracefully, creating a cascade of color that’s simply delightful. They bring a touch of elegance to any garden border or rockery. Trust me, coaxing a new Onosma erecta into existence from a cutting or division is a truly rewarding experience. For many, propagating Onosma erecta is a moderately achievable task. It’s not exactly a walk in the park, but with a little patience and the right approach, you can absolutely succeed.

The Best Time to Start

For the highest chance of success, I find that the late spring or early summer is your golden window. That’s when the plant is actively growing and has plenty of energy to put into developing new roots. You’re looking for stems that are firm but not yet woody. Think of it like this: the plant is at its peak vigour, and we’re just taking a little piece to encourage it to make more of itself.

Supplies You’ll Need

Gathering your tools beforehand makes the whole process so much smoother. Here’s what I always have on hand:

Sharp, clean pruning shears or a sharp knife: A clean cut is crucial to prevent disease.
Rooting hormone powder or gel: This is a little boost for your cuttings, encouraging them to form roots faster.
Well-draining potting mix: A good blend of peat-free compost, perlite, and sharp sand works a treat. You want something that won’t hold excess moisture.
Small pots or trays: For starting your cuttings. Make sure they have drainage holes!
A plastic bag or propagator lid: To create a humid environment for your cuttings.
Watering can with a fine rose: Gentle watering is key.
Labels: You’ll thank yourself later for remembering what you planted and when!

Propagation Methods

There are a couple of ways to go about this, but my favourite for Onosma erecta is stem cuttings. It’s reliable and you can get several new plants from a single parent.

Stem Cuttings:

Take your cuttings: In late spring or early summer, select healthy, non-flowering shoots from your mature Onosma. Using your sharp pruning shears or knife, take cuttings that are about 4-6 inches long. Make a clean cut just below a leaf node (where a leaf attaches to the stem).
Prepare the cuttings: Gently remove the lower leaves from the cutting, leaving just the top couple of leaves. This prevents them from rotting when they’re in the soil.
Apply rooting hormone: Dip the cut end of each cutting into your rooting hormone powder or gel. Tap off any excess – you don’t need a thick coating.
Pot them up: Fill your small pots or trays with your prepared well-draining potting mix. Make a small hole in the center of the soil with a pencil or your finger.
Insert the cuttings: Gently place each cutting into the hole, ensuring the leaf nodes are below the soil surface. Firm the soil gently around the base of the cutting.
Water gently: Water the pots thoroughly but gently with your fine-rose watering can. You want the soil to be moist, not waterlogged.
Create humidity: Cover the pots with a clear plastic bag or place them in a propagator. This creates a humid microclimate, which is essential for cuttings to root. You can secure the bag with a rubber band.

If you have a very established plant that’s crowding its space, division can also work. You’ll want to do this in early spring. Carefully dig up the plant, expose the root ball, and using your hands or a clean trowel, gently pull apart sections that have both roots and shoots. Replant these divisions immediately into well-prepared soil.

The “Secret Sauce” (Pro Tips)

Over the years, I’ve picked up a few tricks that really seem to make a difference.

My first tip is about those cuttings sitting in their plastic tents: Don’t let the leaves of the cuttings touch the sides of the plastic bag or propagator lid. Moisture condensing on them can lead to fungal issues, and we want to avoid that at all costs. Give them a little space.
Secondly, while not strictly necessary for Onosma erecta for everyone, I’ve found that a little bottom heat can really speed things up. If you have a heated propagator or can place your pots on a heat mat, it encourages those roots to form much more readily.
And here’s one that sounds simple but is often overlooked: Mist your cuttings lightly every day or two inside their humid environment. It’s not about soaking them, but just keeping that air moist without creating puddles.

Aftercare & Troubleshooting

Once your cuttings have started to grow new shoots, that’s a good sign that roots are forming! You can give them a gentle tug to test for resistance. If you feel a firm pull, they’ve likely rooted.

At this stage, you can gradually acclimatize them to less humid conditions by opening the plastic bag a little more each day over a week. Once they are showing good top growth and you’re confident they have roots, you can pot them into their own individual small pots with a good quality, well-draining potting mix. Keep them in a bright spot, out of direct hot sun, and continue watering when the top inch of soil feels dry.

The most common issue you’ll encounter is rot. If your cuttings turn black or mushy, it’s a sign of too much moisture and not enough air circulation. This is why using the right soil mix and ensuring good drainage is so vital. Occasionally, you might have cuttings that just refuse to root. Don’t be discouraged! It happens to the best of us. Sometimes, the cutting just wasn’t in its prime, or conditions weren’t quite right.

A Encouraging Closing

Propagating Onosma erecta really is a lovely way to increase your collection and share these beautiful plants with friends. It takes a bit of patience, watching and waiting, but the moment you see that first tiny leaf unfurl on a rooted cutting, it’s a pure gardening joy. So give it a go! Observe your plants, experiment, and most importantly, enjoy the journey of coaxing new life into being. Happy gardening!

Resource:

https://identify.plantnet.org/k-world-flora/species/Onosma%20erecta%20Sm./data