Sowing Seeds Directly Into the Ground or Into Seedling Trays
Once we’ve selected the appropriate seeds or seedlings that are in season, it’s seed sowing or seedling planting time!
In this article we’ll cover the fundamentals of seed sowing, the procedure is quite straightforward and only a bit more complicated than planting seedlings.
Where to Sow Seeds
If you look at a gardening calendar or the seed packet instructions, you will see that there are sowing instructions which specify one of three locations where to plant the seeds:
- Sow seeds directly into the soil.
- Sow seeds into a seed tray or punnet filled with growing medium/potting mix.
- Sow seeds either directly into the soil or into seed tray/seedling punnet filled with growing medium/potting mix.
Direct Sowing Seeds
Most seeds can be sown into pots or punnets (flat seedling trays), and then be transplanted into the garden or into larger sized pots. But there are some plants that don’t like root disturbance and get affected badly by transplanting, so these plants must be directly sown, that is, the seeds must be sown into the ground where the plant is intended to grow.
Here is a quick list of plants whose seeds are best sown directly straight into the ground:
- Broad Beans
- Choko (fruit planted in ground, with top, where shoot emerges, slightly above the ground)
- Garlic (bulbs separated apart and planted below the ground)
- Jerusalem Artichoke (tubers planted below the ground)
- Potatoes (seed potatoes planted below the ground)
- Spring Onions
- Sweet Potato (tubers planted below the ground)
Sowing Seeds Into Seedling Trays
When sowing seeds in seedling trays, use a fine grade growing medium or potting mix, as a mixture containing large coarse pieces of material may prevent the seeds from pushing through the mix when they’re sprouting.
If you can’t find a fine potting medium, just sift the coarse bits out with a gardening sieve or through some mesh of an appropriate size, and use the fine material to sow seeds in.
The textbooks will insist that you specifically use ‘seed raising mix’ to sow seeds, you can find small bags of this in commercial stores, and it’s fairly expensive, but the reality is that you don’t need it. Many new gardeners experience problems sowing seeds in seed raising mix – they find that their seeds sprout but their seedlings only reach a very small size and then completely STOP GROWING, and the resultant seedlings are very thin and spindly!
That’s because seed raising mix has absolutely no nutrients in it, and is totally unsuitable for growing seeds in. It’s actually misnamed, it really should be called SEED COVERING MIX or SEED GERMINATION MIX, because that’s what it’s designed for, and does well.
Some gardeners will insist on using seed raising mix, so if you’re one of those gardeners who wants to spend the extra money, here’s a quick guide on how how to use seed raising mix correctly.
How To Use Seed Raising Mix Correctly in Seedling Trays
For seedlings to grow to the point where they are large enough to transplant, you need a nutrient-rich mix, which seed raising mix is not.
So, how do we raise seedlings using seed raising mix?
- Fill the seedling tray with a quality potting mix (which will contain nutrients) that has been sifted to take the coarsest particles out, or use a fairly fine grade potting mix.
- Place seed on soil surface and gently press so seed is level with the surface.
- Cover with a layer of seed raising mix equal to the height of the seed.
- Water in very gently with a small watering can, being careful not to wash out the seeds.
If you want to use straight seed raising mix (because you bought a huge bag of it), mix it with a nutrient source such as worm castings or a very small amount of well composted cow manure, or both. If your seedlings germinate AND grow, you know you’ve got the right blend!
For more information on seed raising mix, please see my article – Seed Raising Mix – Does It Work?
How to Sow Seeds, Step by Step
Sowing seeds is not that difficult, there are just a few basic steps and rules to follow, and nature does the rest!
Step 1. Make a shallow hole around 2-3 times as deep as the size of the seed into the surface of the soil or growing medium using a dibber or a stick such as a chopstick.
Step 2. Place a seed into the hole. Some gardeners place two or three seeds into each hole as seeds don’t always germinate (sprout).
Step 3. Gently cover the seed in the hole by pushing the surrounding soil or growing medium over it using a garden trowel or other small garden tool.
Step 4. Lightly water in the covered seed with a small watering can, being careful not to wash out the seeds.
When sowing seeds, there are only two rules we need to follow:
- Sow seeds at the correct depth.
- Sow seeds the correct distance apart (when directly sowing into the ground).
If seeds are planted too deeply, they won’t have enough stored energy to push through the soil to reach the light, and they die before they reach the surface. Planted too shallow and seeds can wash away from heavy rainfall or watering.
Seeds need to be planted the right distance apart, because if they’re planted too close, they have to compete with each other for light, water, nutrients and space and don’t grow as well as they could. Planted too far apart and we waste space in the garden and reduce productivity in each garden bed.
TIP: When sowing direct into the soil, and planting large areas, it’s faster to use a hoe to make a shallow furrow or trench to sow the seeds into, rather than individual holes with a dibber or stick. Sprinkle the seeds along the furrow, then use the hoe to cover the seeds, it’s much faster! Where the seed packets specify a distance between rows, make the furrows that specified distance apart.
How Deep Should Seeds Be Sown?
The general rule for planting seeds is that they should be planted two to three times as deep as the diameter of the seed.
The planting depth rule applies equally to both sowing seeds directly into the soil or into seedling trays
There’s no real need to get this exact, as seeds will often germinate regardless of soil depth, just try to get it fairly close.
Follow seed packet instructions for planting depth, and if sowing directly into the garden, follow the recommendations for spacing – how far apart from each other the plants should be spaced.
Most seeds need to be buried into the soil, while some seeds require light to germinate, and prefer to be sown directly on top of the soil. This will be specified on the seed packets.
Note – if you’re collecting your own seeds or are given seeds, and don’t have ‘instructions’, you can look up the seed sowing recommendations in a good gardening book or search for the information online.
How Far Apart Should Seeds Be Sown?
When sowing seeds, the distance between seeds will be different depending on the vegetable or herb. The sowing distance apart is listed on all seed packets, but if you are saving your own seeds, you can refer to a good gardening book or look up the details online.
How to Sow Seeds Into Seedling Trays, Step-by-Step
The advantage of sowing seeds into seedling trays is that warm season seedlings can be started indoors much earlier, giving them a good head start and allowing them to put on a lot of extra growth until the threat of frosts have passed and they’re ready to be transplanted outside in the garden.
To sow vegetable seeds into a seedling tray or punnet, you will need:
- Some sort of growing medium, such as seed raising mix, potting mix or even regular garden soil.
- A seedling tray of some sort of seedling punnets (small shallow rectangular pots) container to hold the growing medium (must have drainage holes).
- Seeds of the plants you wish to grow.
- A watering can.
- A small garden spade or trowel to scoop up potting medium.
- A dibber, chopstick, pencil, or similar implement to make small planting holes for the seeds in the growing medium.
Detailed below are step-by-step seed sowing instructions for planting into trays and containers.
Step 1 – Select a Seedling Tray
Since we’re sowing seeds into a container and not directly into the soil, you’ll need some kind of container to plant your seeds into. You can use anything that can hold your growing medium (seed raising mix, potting mix or even regular garden soil) and that has holes in the bottom to let excess water drain out.
Many gardeners like to use seedling punnet trays like the one pictured below. A single tray can hold many seedlings. Note, these trays have drainage holes at the bottom.
An even better option is a proper seedling tray which is divided up into individual cells, this way each seedling can be removed much more easily without any root disturbance as the roots of one seedling don’t tangle with its neighbours.
Individual seedling punnets work well too, they can be recycled after planting commercially purchased seedlings like the one pictured below.
Step 2 – Fill Tray With Growing Medium
Fill your chosen container with your growing medium, such as seed raising mix, potting mix or even regular garden soil. Level off the surface of the growing medium and pick off any large particles such as rocks or pieces of bark in the mix if present, as they may get in the way of the seeds as they shoot. If the growing medium is way too dry, water it lightly to dampen it slightly.
Step 3 – Make Holes in The Growing Medium to Take Seeds
Next, you’ll need a tool to make small dents of the correct depth in the surface of the growing medium to put the seeds into.
The tool for this purpose is a dibber (also called a dibble) – this is a just a pointed stick for making holes in the ground so that seeds, seedlings or small bulbs can be planted. They usually have depth measurements along their sides. You can also use a chopstick, the blunt end of a pencil, any anything similar.
Press the end of the dibber into the surface of the growing mix to make small holes approximately 2-3 times deeper than the diameter of the seeds.
When using a seedling tray with separate cells, I prefer to make two holes per section so I can put two seeds in. This way, if one seed fails to germinate, the space will be occupied by the other seedling and that growing cell doesn’t go to waste.
Step 4 – Place Seeds Into Holes in Growing Medium
Pour some seeds into the palm of your hand, and then pick the seeds one by one and place them in the holes made with the dibber in the growing medium.
Step 5 – Cover the Seeds
Use the dibber to push growing medium over the holes with seeds in them, to cover the seeds.
Step 6 – Label the Seedling Trays!
When planting up seedling trays or punnets, make sure you label them. This way you know what they are several weeks later, and if the seeds haven’t sprouted, you know which ones failed. When using seedling trays that are divided up into cells, it’s possible to plant more than one type of plant into each tray – in such a case label individual rows.
Labeling is important, I can’t stress this enough. There’s nothing worse than having a large number of vigorous seedlings come up successfully, only to have forgotten what they are!!! Even if you can identify them, you won’t be able to tell apart different varieties of tomatoes for example, and that will really mess things up if you decide to save the seeds at a later date to re-sow next year! You might think you’ll remember, but plants take weeks to grow to size ready for transplanting, and everyone can forget. I know from experience…
Step 7 – Water the Seedling Trays
Watering the seedling trays will get the seeds started. Just keep the soil moist, as the germinating seeds will fail if the growing medium dries out, and they’ll rot if it stays too wet.
Step 8 – Place Seedling Trays In a Safe Location
Place seedlings in a protected location where they will not be subjected to extreme conditions such as wind, rain, frost, harsh sun as young seedlings are quite delicate. Make sure they’re located in a safe place where they will not be eaten overnight by snails or slugs!
Different seeds germinate at different rates, some can sprout in a few days, but they should come up by two weeks time.
Stages of Seedling Growth
It’s easy to get excited when seedlings germinate successfully, but it’s also easy to get to eager and transplant seedlings prematurely!
When seedlings first germinate, they will fold out two long leaves, these are referred to as dicot leaves. Some plants, such as onions or leaves will only have one, a monocot leaf.
After further growth, two different looking leaves will emerge, and start looking like the leaves of the parent plant. These are the seedling’s true leaves, and the rule for transplanting seedlings if that they can be transplanted after they have produced their first true leaves.
if seedlings still look too frail to transplant after their first true leaves, allow them to put on further growth and a few more leaves. When seedlings are a bit more advanced, they tend to be a lot stronger and tend to survive better when first transplanted.
Transplanting seedlings will be the next article in this series!
How to Start Seedlings Early by Growing Them Indoors
If you decide to start seedlings early indoors in preparation for the warm season, there are a few extra steps required.
- Place seedlings on something warm, like the top of a refrigerator or other appliance which stays warm, the bottom heat helps start the seedlings.
- Put the seedlings on drip tray to catch excess water, and avoid making a mess! Don’t overwater, if the seedlings are left sitting in a container of water, their roots will rot!
It’s also possible to cover the seedling tray to keep the moisture in until the seeds have sprouted, but this is optional.
In the picture below is a plastic propagator with a clear lid that is designed to fit over the tray. It’s also possible to purchase cheap propagator covers that fit over plastic punnet trays, which are far more versatile. Propagator covers are usually tall enough to permit some vertical growth. The green “butterfly” vent can be turned to open the holes in the lid to let air in, or closed to retain heat, making it a mini-greenhouse. It’s a luxury, but not a necessity.
Keeping Seed Sowing Simple!
If you think you need a fancy setup to grow seedlings, think again! My mum grew up on a very large commercial farm, and they did things in a back-to-basics fashion way back then. All she does to grow her tomato seedlings is to fill an old rectangular shallow planter with garden soil (!) from the backyard, into which she sows the tomato seeds saved from the previous year’s tomato harvest. The first fruit are always left for seed production.
Once planted up, the container is brought inside and covered with a scrap piece of wood to keep the humidity in until the seeds have sprouted, after which the seedlings are placed on top of a kitchen cabinet near a window where they can get direct morning and midday sun to grow quickly. Once the frosts have passed, they’re planted out in the garden. It’s worked successfully, year after year for her.
Sure, it’s easy to overwater seedlings growing in garden soil because it holds water too well, but this just shows that people adapt to use what they have available, and they can make it work!
If sowing seeds seems like a bit too much work, there’s an much easier way to grow vegetables and herbs, and that’s from seedlings, which will be discussed in the next article – Part 5, How to Plant Seedlings.
Hi Angelo, I am really enjoying this series of articles. Thank you. I just built a raised garden bed & chicken coop, so I will be putting your instructions to the test! Just wondering if parts 5, 6 and 7 have come out & I can’t find them or if they are still coming… Waiting hopefully. 🙂
Thanks Leah, the next article on planting seedlings is on its way, the rest will follow soon afterwards!
Hi Angelo, I’ve have always been somewhat unsure of what to do with the 2-3 times seed width rule for seed planting depth when you have an irregular shaped seed. Take broad bean or cantelope seeds for example, where the seed height, width and depth are all quite different. Do you work with 2-3 times the longest diameter of the seed, and does that affect the way you should orient the seed when you place it in the ground? Many thanks. Susan
Hi Susan, that’s a great question. I just use the shortest dimension, so if a broad bean seed were sitting flat on a tabletop, I would plant it 2-3 times that height. With bigger seeds like broad beans, it’s not too critical, as many people push the long end into the soil and drive it down a short distance into the soil with their thumb, assuming the soil is loose enough. The concern is with small seeds, if they’re buried too deeply, they don’t have enough energy reserves to push their shoot a long distance through the soil, and if they’re too planted to shallow they might get washed out by rain.