SOWING IN VERMICULITE

I began using this method 5 years ago, and I now sow almost all of my seeds in vermiculite; including the processes of both winter sowing and indoor sowing. It’s cheaper and cleaner than sowing in soil; less time-consuming because you won’t need to water the seeds and seedlings until you transplant them.

Here are a few key points to consider:

-You can use any container that has no holes in the bottom portion, or in the lid. This is less time-consuming than other sowing methods; there’s no need to drill multiple holes for drainage and water penetration. Humidity and soil moisture remain constant, whether you winter sow or sow indoors because the seeds are sown in completely closed containers. No need to check moisture levels on seeds sown indoors, or during a dry period for winter sown containers; additionally, there are no soggy soil complications in winter sown containers after heavy rain or snow. Seedlings will not require supplemental watering until they are transplanted.

– Sowing in vermiculite is cheaper than sowing in soil. I can sow 300-400 containers (small, medium and large) with one big bag of vermiculite.        A large bag costs about $25.00, and weighs very little, so there’s no lugging around heavy bags of soil.

– It’s cleaner. I used to do my sowing in the stables, but now I can do it in the kitchen. I may drop some vermiculite, but it won’t stain the floors or rugs. An additional benefit is that vermiculite won’t stain your hands, as soil so often does.

– Vermiculite is a natural mineral product that expands under commercial heating techniques, thus resulting in elevated water-holding capacities. It is commonly used for insulation purposes, which can make it an economical purchase in stores that sell insulation materials. You can, of course, purchase vermiculite in smaller quantities from garden supply centers or via the Internet if you have just a few containers to sow.

– Safety: years ago, there were instances of contaminated vermiculite, but with today’s strict controls, that’s now a thing of the past.

– Transplanting seedlings grown in vermiculite is almost always easier than transplanting from soil. Vermiculite particles are lightweight and will generally separate cleanly from one another, so delicate roots won’t be damaged as easily during removal. Any vermiculite clinging to the roots can safely remain attached as the plant is placed into the transplant area.

Getting started:

Care must be taken to remove as much chaff as possible when using collected seed. Excess chaff may cause mold to grow in covered containers.

How to remove chaff:

A great many of the largest particles of chaff can be removed using different sieves and a makeup brush, or small paint brush. To remove the remaining dust, gentle puffs of air directed toward the group of seeds -beginning from a perpendicular angle, and moving downward to nearly horizontal across the seed surface will also help to blow the chaff away.

Cleaned seeds, ready to be sown:

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Sowing medium preparation:

Begin with a large bowl or smaller sized bucket, and a large volume sieve.

Fill half of the preparation container with dry vermiculite and pour water over it until just covered. Then immediately pour it in the sieve, so that the vermiculite doesn’t get too wet. It’s very important to pour it into the sieve promptly after watering; this will ensure the perfect moisture level for sowing the seeds. Gently shake the sieve a few times to get rid of the extra water. Now it’s ready to use.

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Now you can begin to fill containers with your pre-moistened vermiculite. Prepare as many containers as you’ll sow that day.
Using a large spoon or ladle, begin filling the containers. The layer must be between one and four inches high, depending on the kind and size of the seeds you’re sowing. One inch will do for very small seeds that need light to germinate; while four inches might occasionally be used for very large seeds.
Gently press the layer with the bottom of another container to settle the vermiculite. Once the desired depth has been attained, it’s time to sow the seeds!

Sowing the seeds:

– Seeds that need light to germinate are exceptionally good candidates for sowing in vermiculite. Just scatter the seeds on the surface; the continuing expansion of the moistened vermiculite will provide good surface contact. Do not apply water to “settle” the seeds, this will ruin the composition of the previously prepared vermiculite. Use a spoon to lightly cover seeds that require it, and if necessary, gently tamp down the surface with the bottom of another container. It may seem that some areas are covered deeper than necessary due to the clumping action of moist vermiculite, but don’t worry; vermiculite admits greater amounts of light than soil mixes. Cover containers with clear lids, apply a label, and position containers in a spot with bright indirect light.

There are some seeds that need complete darkness to germinate. They can be sown in the vermiculite too, but you need to place the container in the dark until germination takes place. These containers can be covered with transluscent lids, but they must be removed after germination.

Once covers are removed soil moisture must be determined on at least a once daily basis. A single pass with a sprayer should be sufficient. Keep in mind that there is no drainage, so water sparingly to avoid problems due to over-watering.

Finished containers. Labels are written in pencil for fade-resistance:

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Here are pictures of seedlings in containers. 

The first one is Lupinus pilosus.

Lupinus pilosus

The second one is Ageratum houstonianum. The 2nd one needs light to germinate, so I just scttered the seeds on top of the vermiculite.

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Additional notes:

When sowing water plants, you’ll need to add between one-half inch, to two inches of extra water to the container before sowing seeds.

Almost all seeds can be successfully sown in vermiculite – including; fruit, trees, shrubs, vegetables, annuals, perennials, etc. There are noteable exceptions, however; some woodland plants require microbial activity to germinate successfully. These seeds would best be sown in-situ, or by using a standard method; employing the use of a compost mix when available.

If you winter sow vermiculite containers and place them outdoors in the elements, you’ll need to add some weight so they won’t be blown away. Simply add a few heavy stones or medium-sized rocks to the boxes with containers.

The picture of a weighted box with containers:

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The containers in my unheated greenhouse:

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An unheated greenhouse could provide wind protection for your containers, and depending on your climate, may even be cold enough to house winter sown containers.

Take an inventory of the number of seeds you plan to grow, gather up some containers and a bag of vermiculite, and you’re ready to sow. It’s just that easy. You’ll enjoy quicker clean-up, with less backache as well; what a joy!

If you have any questions, please use the ‘contact’ button to ask your questions.

Special thanks to Chelle for making sure this article is in proper English.