How to raise seeds successfully in pots

Over the recent years, HOGS has set up a stand at the Living Smart Festival in Lake Macquarie.

This year, 2023, the Festival is on 16 September and we would love to see you there. Generally we sell seedlings, plants and run some mini workshops as well as share information about growing and of course about our HOGS family and joining.

We would love for members to support our stand by attending the Festival and/or by growing some seedlings and donating them to the stand for us to sell. Now is the time to start raising those seedlings so we thought we would share some information about how to do this at home, especially if you are new to the growing scene. Plus, you never know when you may learn something new.

In this article, we will talk about how to grow seeds in a container or pot and share a seed raising mix recipe. Raising seeds direct will be covered in another article.

WHAT IS A SEED

A seed is a tiny undeveloped plant embryo capable of developing another plant. It requires moisture, air and warmth to germinate.

Moisture softens the seed coat (called a testa). This enables the seed to swell and oxygen (air) to enter which starts a process where the stored food energy of the seed is released and made available to the plant embryo. Within the seed is stored enough food so the embryo can break through the soil surface, open its leaves and begin photosynthesis. This is the process described very simply and knowing the process helps us to understand why seeds needs moisture air and warmth. Air pockets in the soil are needed because the embryo needs the oxygen. You need to water seeds to soften the testa and enable swelling. Warmth is needed because temperature influences the hormones and enzyme activity within the seed causing cell formation and development.

WHAT TO SOW

For seeds to sow now you can refer to the July Growers Guide and very soon the August Growers Guide.

You should also check seed packets for directions.

SOWING WINDOWS - ANNUALS VS PERRENIALS

Annual seed needs to germinate, grow and produce during one season, or before the ideal weather conditions change. You can check whether there is enough time to grow and harvest by seeing how many weeks to harvest on the packet and then counting forwards that number of weeks from your planned sowing date to see whether you think the weather and soil are still warm enough for the plant to produce.

INDOORs, OUTDOORS and HEAT MATS - SOIL TEMPERATURE

Many seeds need to the soil to be above or below a particular temperature for them to germinate. If the soil is not, then the seed may not germinate or grow healthily. Generally these temperatures are 10C, 20C, 25C and 30C. Most summer crops need a soil temperature over 20C but below 30C to germinate. Tropical summer crops generally need a soil temperature over 25C. Most winter crops need a soil temperature below 20C so they do not immediately bolt, but above 10C in order to germinate.

Knowing this will help you determine whether you start your seedlings indoors (where you generally know the ambient temperature), outdoors in a seedbed or outdoors (under protection from frost) using a heat mat which sits under the seed trays.

SOWING INTO POTS

Generally we sow into pots to get a jump start on the season or when we are sowing very fine seed and usually for seed which produces a crop above the ground. Sowing in containers gives you greater control and flexibility but it takes more time and dedication to care for them.

Usually seedling trays are used for sowing and this is the case because they are shallow so the soil stays warmer more easily. Once they have produced 4-6 leaves you can then move them to deeper pots. Or you can use plantable pots which remove the need for pricking out seedlings and reduce transplant shock.

You can make your own seed raising mix (see instructions below) or purchase a good quality mix because generally using garden soil in a pot is too dense (lacks air), shrinks and generally becomes hydrophobic causing many issues for the seed to combat in order to grow strong and healthy.

Fill your seedling trays or pots with soil and press down slightly to compress the soil so there are not too many air pockets. Sow your seed on the top and cover with a light layer of soil or coir, or not at all if the seed is super fine like celery. Then, label your seedling tray or pot and place seed in a warm, sheltered position with good light but not direct sun. Keep them damp. If you are watering in winter, sometimes it can be helpful to fill your watering can with lukewarm water from the kitchen tap rather than the outdoor hose. Or water during the warmest part of the day. This helps to keep the soil warm and not shock the seedling.

Prick out seedlings if they are planted too closely or will need larger pots when they have 4-6 leaves. This prevents issues such as damping off and spindly growth. If the seedling looks unwell or not strong, discard it. Handle all seedlings with gentleness as they are very delicate. Provide nutrient rich water such as seasol every few days once the seedlings have leaves because most commercial seed raising mixes do not provide much in the way of nutrients. Once you see roots coming out of the bottom of the pot, then you know it is time to harden off the seedling by slowly removing heat, taking it outside, or placing it into the open (this takes place gradually over a few days) before transplanting into the ground. You will need to continue to water the seedlings during hardening off.

WATERING

How much is too much? Generally, you do not want to push the soil and see a water puddle forming. Water logged soil causes damping off. Watering once a day or sometimes every second day is ideal in winter. The soil does not dry out as fast as it does in summer. If the soil is dry on the top, give the seedling a light water.

HOST A POTTING-UP PARTY

Sometimes it is fun to get some friends together and host a small party where everyone brings some seeds to share and you all pot them together. This way you learn about new seeds, grow different foods and have fun at the same time.

SEED RAISING MIX

There are many different ways folks make their own seed raising mixes. Here is one recipe:

1 part vermiculite or pearlite or builder's sand

2 parts seed raising coir

2 parts compost

If this does not make much sense, then work in fifths of the container. If your container holds 1kg, add 200g vermiculite (1/5), 400g coir (2/5), 400g compost (2/5). Adjust to the size of the container or amount of mix you want to make.

And, I like to add some worm castings but if you have none available then a sprinkle of blood and bone will do the trick too.

Share with us your experiences on the HOGS Group Facebook page. Feel free to ask questions in the comments of this blog or on our group page.

Written by Melissa Fogarty Blue Boat Farm