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Tag: seedling mix

How Can I Prevent Damping Off When I Sow Seeds?

“How can I prevent damping off when I sow seeds?  That is my problem.” Question from Bev of Philadelphia, Pennsylvania

Answer: This is a problem that I have faced many times starting seeds in university greenhouses, professional greenhouses, and at home. Thankfully, the solution is pretty simple, and it all involves keeping everything clean. Let’s start by covering the sources of damping off disease.

What is Damping Off?

Damping-off is a disease of sprouting seeds and seedlings that is primarily caused by two soilborne fungi, Pythium and Phytophthora spp. They cause rot and death in developing seeds and seedlings, usually at the roots or base of tender developing stems. Damping-off is a problem when growers keep the soil too moist and the disease is present.

To keep damping-off from taking hold you need to start with good soil, clean pots, and follow up with smart care.

Sterilizing Mix and Pots

Disease-carrying mix is the biggest concern. I used to work in large-scale greenhouses where they used big heater/steamers to sterilize mix at a temperature just high enough to kill any soilborne diseases (around 180°F). This is essential for growers that reuse mix, but careful growers sterilize new mix, too. Why? Because the airborne spores of damping-off fungi can be practically anywhere –especially in places where plants are being grown.

Additionally, unused seed-starting mix, like Black Gold Seedling Mix, is typically produced in clean facilities and bagged pathogen-free. But, if bags tear in transport and/or bags are not stored properly, Pythium and Phytophthora spores can infiltrate. Bags of seedling mix should be lightweight (meaning no water from the outside has seeped into the bag) and without tears. Improperly stored open bags at home can also be a danger. If you are not certain of your mix’s cleanliness, then it’s time for home sterilization.

I sterilize seed-starting mix using this fast and easy method.

Ingredients: Seed-starting mix, a 9″ x 13″ cake pan, 1/2 cup water, aluminum foil, and an oven.

Directions: Preheat your oven to 180°F, fill your pan with seedling mix, sprinkle it with the water, cover the pan with the foil, and bake it for 30 minutes. After baking, remove the pan from the oven and allow the mix to cool before using.

These diseases can also hang out on dirty old pots, so in the greenhouse, we’d also wash used pots and trays really well in hot water with good dishwashing liquid and sometimes a dash of bleach. I do this at home as well.

Seed and Seedling Care

Aside from starting with clean soil and pots, it is essential to discourage wet soils when starting and growing seedlings. I generally keep newly planted seeds gently sprinkled with a bottle waterer (see video below), so the soil is never over saturated. Once my seedlings pop up, I bottom water by adding 1/4 to 1/2 inch of water to the water-holding trays every two to four days, depending on seedling size. It also helps to encourage airflow, to help soil surfaces dry more quickly, and keep trays warm with a heat mat.

These cultural practices will definitely kick your damping-off problem away for life!

Happy gardening,

Jessie Keith

Black Gold Horticulturist

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The Best Seedling Mix for Germination and Cuttings

BG Seeding Mix frontBlack Gold® Seedling Mix is the best seedling mix for germinating seeds and propagating cuttings. The mix is designed to promote better root development in young plants.

We start with a careful blend of Canadian Sphagnum Peat Moss (which has been double-screened to remove larger particles and sticks); fine perlite and vermiculite to give seedlings and cuttings the aeration and moisture retention they need to develop a good root system. A wetting agent ensures rapid water penetration, and the fine texture encourages high germination and rooting. Transplanting your seedlings and cuttings will be a breeze when plants develop strong root systems as they are grown in Black Gold® Seedling Mix.

When it comes to germinating seeds, it’s simple – all you need is water, light and Black Gold® Seedling Mix. Making sure the growing media stays moist and seeds or cuttings have plenty of water in the early stages of germination or rooting is critical. Our seedling mix is designed with both peat moss and vermiculite, critical ingredients when you want to retain just the right amounts of moisture in your soil. Whether you are starting your seeds in a pot or a tray, they should be kept at temperatures between 60 and 70 degrees and placed in bright but not direct light – a southern exposure is ideal. Some seeds need darkness to germinate, so be sure to check your seed packet for details.

Black Gold® Seedling Mix is made with the same ingredients we use to make our seedling/propagation mixes for commercial greenhouse growers. Seeds typically need to be covered with Black Gold® Seedling Mix at a depth three times the diameter of the seed you are germinating. Larger seeds and seeds planted during warmer times of the year typically need to be planted deeper. Germinating your own seeds or rooting your own cuttings is a rewarding experience and one of the great delights of gardening. So when you are faced with the question, “Why buy a premium seedling mix potting soil?” the answer is clear. When you use Black Gold® Seedling Mix your seedlings and cuttings will have a great place to grow up.