Preventing damping off: How to save your seedlings

With immense pride, you’ve sown seeds for either a veggie patch or a showy garden. A steady shower of water brings forth the first timid shoots. But –wait– those young sprouts don’t look so good! They’re feeble, soft… probably suffering from damping off!Let’s talk solutions and explanations.

→ Get technical: understand damping off

What is seedling blight?

Seedling blight, or damping, is a fungal disease caused by either of these fungi: Fusarium, Rhizoctonia, Pythium, Botrytis or Phytophthora. These fungi weasel their way into the plant’s core and start wreaking havoc. The poor seedling, too young to fend off such a disease, withers away in hours. Before you know it, all your seedlings are under attack, so speed is of the essence!

More worrying is that these fungi live everywhere: in soil, potting mix, and even on seeds themselves.

How to recognize it?

• Plant goes limp, lays down on the ground.
• Stem base turns brown or red and thins out.
• Seedling turns necrotic.
• Sometimes, seedlings rot before they even emerge from the soil.

Which plants are affected?

Every plant can suffer from this disease, be it herbs, flowers, or veggie seeds.

Risk factors

Fungi, like those causing damping-off in seedlings, love moist environments.

If sowing in a greenhouse, remember to air it out often, especially during a rainy spring.

Avoid dense, deep sowings. Sow in loose soil that you’ve worked through beforehand, using a broadfork if it’s in open ground or with well-draining seed compost mixed with sand. Also steer clear of excessively rich substrates.

Damping off natural prevention and treatments

Today, there are no natural curative treatments, only prevention methods. Disease spreads so fast that, if you spot it, best just toss affected seedlings away.

How to prevent its appearance?

• Use a special seedling compost that’s perfectly balanced, well-drained, and not too rich
• Don’t sow too tightly
• Disinfect your tools before use, this holds for all gardening tasks
• Refer to label for sowing depth
• Air out rooms housing your seedlings regularly
• Water regularly but with a fine mist, substrate should never be waterlogged, only moist
• Keep your seedlings at a temperature between 60°F and 70°F (15-20°C) ideally.

Natural prevention:

Fermented horsetail tea

Fermented horsetail tea is an effective antifungal used in spraying. It’s a concentrate that needs dilution: 1 quart of manure for 9 quarts of water (1L manure for 9L water). Simply spray it on seedlings when watering. You can use a hand sprayer to mist seedlings with your tea. Don’t use it for each watering, only once a week, during germination. The rest of year, a monthly spray is enough for all your plants.

Charcoal

When prepping your substrate, add powdered charcoal to your special seedling compost. It curbs humidity and thus appearance of certain fungi. Count about 3 lbs of charcoal powder per square yard of soil (1.5 kg per square meter). Get horticultural charcoal, not supermarket-sold BBQ charcoal. You can also use your own charcoal if you have a fireplace.

Garlic infusion

Antibacterial and antifungal, garlic is another natural ally against damping-off. Use it like fermented horsetail tea, in spraying. To make this infusion, simply put 1 lb of chopped garlic in 1 gallon of water (500g in 5 liters). Bring to a boil, then let simmer for 30 minutes. Then, turn off the heat, cover the container and let it sit for half a day. All that’s left is to filter and pour this solution into jugs and bottles.

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