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How to Propagate Soft Annuals


July 10, 2018
Category: Growing Tips

Unrooted Cuttings Bagged and Ready to Ship

These unrooted cuttings are bagged and ready to ship.

One question we get asked a lot is, “How do you propagate unrooted cuttings?” North Carolina Farms offers both rooted and unrooted orders in certain plant varieties.

Greenhouse owners that have never purchased unrooted cuttings(URC) before often wonder if it’s something they should try.

The answer all depends on how comfortable you feel with attempting the process. To help you make that decision, here is a guide on how to propagate soft annuals.

Planting and Misting

  1. Start with clean materials. This doesn’t mean you’ve given your plants a bath. Clean materials are cuttings that are fresh and free of virus, diseases, and fungus. In other words, the best your plants have to offer.
  2. Choose a soilless media. Take your cutting and plant it directly into a soilless media such as peat moss with perlite. The important part is that this media is well drained.
  3. Put your cuttings into a propagation bed. Most of the time, you will need to start your cuttings in a cell pack tray in the propagation bed and then step them up to your finished container after they are rooted.
Propagated cuttings in 105 cell trays

These propagated cuttings were just planted in their cell packs and have been under mist for several days.

But What is a Propagation Bed?

A propagation bed is an area where you root your cuttings by adding bottom heat. Bottom heat provides gentle warmth from below rather than subjecting the plants to heat from the top. If you keep the soil warmer than the air above the plants, especially at night, the cuttings will generate roots faster.

In a propagation bed, keep the soil temperature around 70 degrees. You want the soil to stay as warm as possible without drying out the plant overnight.

The biggest thing you don’t want to do is stress the plant with dehydration.

So Don’t Forget The Mist

The other essential component you need for a propagation bed is intermittent mist. Intermittent mist consists of a light mist for short bursts, spread throughout the day. Your mist program will vary depending on the type of plant, the time of year, and your weather conditions for that day.

Here’s a sample schedule for an average sunny winter day. (We are misting plants that need high mist, such as petunias, impatiens, calibrachoa, and vinca vine.)

9:30 am– Start mist. Give short bursts of mist (10 to 15 seconds) every 15 minutes.

3:00 pm– Turn off mist. We want our plants to dry out a little bit and not be fully saturated all night long.

5:00 pm– Check the plants. If they don’t look nice and turgid (full of water), then you may need to schedule a short burst of night mist for every hour or two.

There are also low and no mist plants, which would receive mist only once an hour during the day. Some low mist plants are begonias and foliage plants. Succulents receive no mist.

In the summertime, your misting schedule would remain the same, but your start time would be around 8:30 am and may continue to as late as 5:30 or 6:00 pm.

Continue this misting schedule until the plants start to harden off or callus over a little bit. At this point, you can cut your mist intervals back to every 30 minutes instead of every 15.

But What About Cool, Cloudy Days?

On cool, cloudy days, we don’t run mist. Or we may decide to run it a couple of times during the day. The bottom line is, the plants do the talking. If they look stressed, then give them more mist. If the soil looks waterlogged, you’ve given them too much mist. Keep them as dry as possible without crossing the line.

Here at North Carolina Farms, we’ve done some trials with mixing Capsil into the first mist our cuttings receive. Capsil is an adjuvant. That means it’s a substance that helps chemicals mix into water well. But it also closes the capillaries on the back of the leaf of the plant. This keeps plants from transpiring all of their water.

We have a designated tank that we put the Capsil into at a very low dose. It seems to help keep the plants turgid for the first couple of days. This is great news, but it doesn’t give us a pass to neglect checking the health of our plants. Nice, fat, turgid plants can still become unhealthy.

Problems That Can Arise

The low light and high humidity of misting create a perfect storm for certain problems.

  • Fungus, like botrytis, spreads rapidly in this environment.
  • Root rot takes hold under wet conditions.
  • Some pests, including fungus gnats, thrive in saturated soils.

Lighting and Rooting

Some plants, like lantana and purslane, really want to have a lot of light. They like it as bright as possible. Others, like most foliage and hedra, prefer some shade. This means you need to plan when you are going to be rooting based on the space you have available and the different environments you are able to create.

Timing

As you are planting your cuttings, plan ahead. Some crops will only need a week’s worth of mist while others will require potentially two weeks worth of mist. You may see roots within seven days on some varieties while others might take four or five weeks before you get roots established.

So as you are planting your plants, think about what timing makes sense. Otherwise, you’re going to create more work for yourself later. Reducing stress by giving your plants sufficient time to be well rooted before transplanting will increase your chances of a successful, healthy crop.

Pro Tip

If this process sounds complicated, we recommend buying in unpatented rooted plants and experimenting with propagating these as they grow out. Simply take your own cuttings as you are natually pinching your pots and follow the procedure we outlined. This way you don’t risk your season on a process you’re not used to.