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Seed sowing: where did I go wrong?

Growing plants from seed is incredibly rewarding when all goes well
Image: Shutterstock

There’s nothing quite like the exciting promise contained in a handful of seeds, and nothing more disappointing than their failure to germinate. Even worse is watching your precious seedlings emerge, only to see them fail to thrive or wither and die.

Here are some of the most common ways that things go wrong, and how to avoid them:

Why didn’t my seeds germinate?

These tiny seeds require just a thin dust of soil to cover as they need light to germinate
Image: Shutterstock

There are many reasons why seeds fail to germinate, and not all of them are your fault! In order to germinate successfully, seeds require several needs to be met. These include water, oxygen, temperature and correct levels of light. Once you know the things that can go wrong, these setbacks are easy to avoid.

The seed was old:

Check the ‘sow by’ date on the packet. Seed that’s beyond this date will often still germinate but the success rate is reduced. Some seeds, such as parsnip, lose their viability rapidly so it’s worth buying a new packet each year.

It was too hot or too cold:

Always check the recommended germination temperature on the seed packet. Extremes of heat or cold may prevent seeds from germinating so it’s well worth monitoring the soil temperature with a soil thermometer. Most species can be sown successfully indoors at temperatures between 13C – 21C – easily achieved in a heated propagator or on a bright windowsill. Once germinated, you can move your seed trays to a slightly cooler position.

Outdoors: Keep an eye on the weather and avoid sowing if the soil is cold and wet, as this will cause the seed to rot. Seed packets usually advise when to sow direct outside but this will vary between warm southern gardens and cold northern locations. In the north it may be necessary to sow a month later than the seed packet suggests if the soil remains cold. Help early sowings along by using cloches to warm the soil.

The soil was too wet or too dry:

Too dry, and your seeds won’t germinate. Too wet, and they’re liable to rot. Ensure that seeds are kept evenly moist by thoroughly wetting and draining the compost before you begin. After sowing you can cover the seed tray with a sheet of glass or clear plastic to retain moisture – the compost should remain damp for several days or more.

If the soil surface begins to dry out, simply stand the seed tray in water until the surface becomes moist – but be sure to let it drain again. Remove the glass or plastic as soon as the seeds begin to germinate to prevent the seedlings from rotting.

Outdoors: Wet, poorly drained soils or dry, sandy soils can be difficult environments for seed germination. Both can be improved by adding plenty of organic matter such as well rotted manure or homemade compost. On wet soils this will improve drainage and air circulation, while on dry soils organic matter acts as a sponge, holding water in the soil for longer.

The seeds were sown at the wrong depth:

Some seeds need light to germinate, and some don’t. The amount of light that the seed receives is determined by how deeply it’s sown. Check the seed packet before you bury your seeds beneath the soil – if they need plenty of light to germinate they’ll only require a thin dusting of compost or vermiculite to get them underway.

If no instructions are provided, the size of the seed gives a good indicator of how deep to sow it. Very small seeds such as begonia and lettuce only need a light covering of sieved compost or vermiculite. Larger seeds like sunflowers and beans need to be sown several centimetres beneath the surface. As a general rule of thumb, most seeds should be planted at a depth of 3 to 4 times their own width.

The seed needed special treatment:

Did the seed packet mention pre-chilling, chipping, scarifying or soaking? Some treatments may sound a bit strange but they’re essential to help the seed germinate. You can find a full description of different techniques in our specialised sowing information article.

The seeds were eaten:

Outdoor sowings of beans, peas, sunflowers and other large seeds are often at risk from attack from the moment they’re sown. Mice and birds love to dig them up for an easy snack. Protect your seeds with cloches, chicken wire or netting to give them time to germinate safely. If you use netting, secure it carefully to avoid entangling birds.

For a quick recap on how to sow seeds correctly, read our seed sowing guide.

Why did my seedlings fail?

This gardener carefully checks the size of the roots before pricking out his seedlings
Image: Shutterstock

Transferring delicate seedlings from seed trays to individual pots provides each seedling with the space, light and nutrients it needs to develop into a strong, healthy plant. But this can be a critical time in the plant’s development and things don’t always go smoothly.

Here are some of the most common mistakes to avoid:

The seedlings were pricked out too early:

As a rule of thumb, most seedlings can be pricked out when the first true adult leaves show (i.e. the second set of leaves after the initial seed leaves or cotyledons).

But before you begin, it’s always worth checking that your seedlings have sufficient root growth to cope with the transplant process. Simply lift one or two seedlings out of the tray with a dibber and take a look. If the roots are still very tiny then postpone pricking out for a few more days. It won’t do them any harm and the extra time will help them cope better with the transplant.

The seedlings were pricked out too late:

It’s easy to sow too many seeds and then find that you don’t have time to prick them out. Delays in pricking out, especially for fast growers like tomatoes, can lead to competition for light and nutrients. If left for too long, your seedlings will start to look sickly as the nutrients in the soil are depleted. This can cause a significant check in their growth even after pricking them out.

The seedlings were damaged during pricking out:

Your delicate seedlings can be easily bruised and damaged so you should never handle them by the root or stem. Use the cotyledons as ‘handles’. Once the true leaves have formed, these seed leaves are no longer required so it doesn’t matter if they get damaged.

The seedlings just died:

Did your seedlings mysteriously keel over, or rot away at the base of the stem? These symptoms are signs of damping off, caused by a number of fungal diseases that often occur if the soil is persistently wet. To reduce the risk of damping off take the following steps:

  1. Use fresh, commercially-produced compost instead a half-used bag from last season.
  2. Always wash and dry pots and seed trays before re-using them. Disinfect them with a little diluted Jeyes Fluid.
  3. Don’t over water – let the compost dry out slightly between watering to keep fungal spread at bay.
  4. Water with clean tap water instead of using rain water.
  5. Keep seedlings well ventilated to ensure good air circulation.

The seedlings are tall and spindly:

Seedlings naturally grow towards the light, but when light levels are poor it can cause the growth to become tall and spindly. Warm temperatures will encourage leggy growth too. If you’re growing plants on your windowsill, this can be a real problem, resulting in thin spindly stems that flop over. Try to use the brightest windowsill possible (although it’s best to avoid direct strong sunlight as this may scorch your plants.)

The plants all died when they were moved outdoors:

Always check the weather before you move your plants outside. Cold temperatures, scorching heat, wind, and heavy rain can all damage or even kill your young plants. Even if the weather conditions are favourable, plants that have been grown indoors need to be hardened off before you can plant them outside. This allows them to acclimatise to the temperature, air movement and weather conditions before you plant them out. Place them outdoors in a sheltered position during the daytime and bring them back in at night. After 7 to 10 days, they should be able to cope with the big outdoors!

To properly refresh your mind and get the process clear, read our comprehensive article on pricking out and hardening off.

There’s nothing quite as satisfying as raising a plant entirely from seed. We hope we’ve given you lots of ideas to try if your seeds are failing to produce results. Good luck!

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Written by: Sue Sanderson

Plants and gardens have always been a big part of my life. I can remember helping my Dad to prick out seedlings, even before I could see over the top of the potting bench. As an adult, I trained at Writtle College where I received my degree, BSc. (Hons) Horticulture. After working in a specialist plantsman’s nursery, and later, as a consulting arboriculturalist, I joined Thompson & Morgan in 2008. Initially looking after the grounds and coordinating the plant trials, I now support the web team offering horticultural advice online.

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If you have ever experienced problems with seed germination or with pricking out and hardening your seedlings, we’ve put together all the possible reasons for these failures, and how to avoid them next year!

10 Reasons Your Seeds Aren’t Germinating and How To Fix It

Published: Mar 24, 2020 by Elizabeth Waddington · This post may contain affiliate links.

It is very disappointing when you excitedly sow your new seeds, only to find that germination rates are low. You might even encounter the problem of having no seedlings appear at all. You need to work out why your seeds aren’t germinating.

Fortunately, it is often quite easy to pinpoint the cause, and there are a number of simple measures you can take to solve the problem, whatever it turns out to be.

Environmental Problems Causing Poor Seed Germination

The first thing you have to do is think about environmental problems. Environmental problems are often the most likely cause of germination problems. Different factors in the environment will be important in determining how successfully seeds will germinate.

The three key factors in germination for common crops are how much water they get, oxygen levels and temperature.

1. Too Little Water

Water is usually required for seed germination to take place. As seeds mature, they dry out. In order to germinate successfully, these mature seeds need to take in a lot of water. It is only when they have absorbed sufficient water that cellular metabolic processes and growth can take place.

When seeds absorb water, hyrolytic enzymes will begin the process of turning stored food resources into chemicals that are necessary for processes in germination.

Seeds also often require water for the coating of each seed to break down, so that the seedling can emerge.

If you have poor germination rates, this may be because you have not provided enough water for these processes to take place. If the soil in your seed trays, containers or planting areas is too dry, you should be able to see or feel this fairly easily.

Water well, taking care not to wash your seeds away or push them too deep into the growing medium, and your seeds may well still germinate in time.

2. Too Much Water

Generally speaking, the goal will be to provide enough water to moisten the seeds. But you do not want to soak them. Of course, the amount of water required will depend on the particular type of seeds you are trying to germinate.

Overwatering is one of the leading causes for poor, patchy or non-existent germination. Watering too much can cause waterlogging and compaction, which ties into the point below. An overly humid environment can also make it more likely that you will have a problem with damping off – more on which a little later in this article.

If you have watered too much, you may be able to recover things by letting the seed growing medium dry out somewhat. However, unfortunately, if the overwatering has led to one of the other problems described below, it may be too late to save them and you may need to start over.

3. Seeds Are Not Getting Enough Oxygen

A germinating seed needs oxygen for metabolism until the process of photosynthesis takes over. Before a seedling’s leaves develop, it largely derives its energy from aerobic respiration.

Oxygen needs are interlinked with water requirements. Coatings of certain seeds need to be broken down before they can absorb water and oxygen from the environment.

Both under watering and over watering could cause seeds not to get enough oxygen for germination. Under watering may have caused problems with the coating not breaking down. Over watering may have caused the soil to become waterlogged and compacted. Compactions makes it more difficult for oxygen to get through.

But another mistake may have meant that seeds did not get the oxygen they needed. You may have buried your seeds too deeply.

Check the seed packet, in gardening books or online to see what depth seeds should be planted at. Then, if you feel this may have been the mistake you made, have another go.

You may also have chosen the wrong growing medium for the seeds you are trying to grow. This too could lead to problems with seeds not getting the oxygen (or water) they need to germinate. Make sure you know what type of growing medium is required, and replace your growing medium if you made the wrong decision last time round.

4. Temperatures Are Too Low

Other common problems with seed germination revolve around temperature. Temperature will have a bearing on cellular metabolism and growth rates.

Seeds will generally germinate within a certain temperature range. They will not germinate at all outwith this temperature range, and at the extremities of the temperature range, germination rates may be significantly reduced.

Many common garden crops germinate effectively at around the average room temperature in heated homes (60-75 degrees F.). However, there is a wide range in temperatures required.

Some seeds germinate at temperatures just above freezing, some when the soil is surprisingly cool, and others only when soil has warmed significantly. A period of cold (vernalization) is required to break dormancy for some seeds. Meanwhile, others germinate only in response to an abrupt swing in temperatures (like that that marks the changing of the seasons).

Successful growing depends on understanding the role that temperature plays on the seeds we wish to grow.

Problems with the temperatures being too low are usually experienced when seeds are sown directly outdoors. You may simply have sown your seeds too early. Or the temperatures may have seen a sudden and unexpected night time dip. In a cool or cold temperate climate, late frosts can sometimes be a problem with early sowings.

To avoid this problem, you may wish to start seeds indoors before transplanting them to their final growing positions once the weather (and the soil) more reliably warms up.

If you have a short growing season, it can be important to start sowing seeds early. As well as considering starting seeds indoors, you could also consider creating a hot bed or a cold frame in which to sow your seeds, or protecting seeds and young seedlings with a greenhouse, polytunnel, row cover or cloche.

Soil will warm more quickly under one of these structures. So it could be easier to achieve the temperatures that are required for germination.

5. Temperatures Are Too High

If you are starting your seeds indoors, or in the height of summer in a warmer climate, you may have the opposite problem. Many seeds will fail to germinate above around 90-95 degrees F. If they have experienced temperatures approaching those inside your home, or in the garden, that may be the reason for the poor or non-existent germination.

If you are starting seeds indoors, check that there are no heat sources causing a problem in the vicinity of your seed growing area. Sometimes, temperature fluctuations that are too extreme may be the problem.

Are your seeds, for example, too close to a radiator, stove or oven that goes on and off? If your greenhouse or polytunnel is getting too hot, be sure to open the structure up to create adequate ventilation.

If you are trying to germinate seeds during a very hot summer, try to provide shade to bring the temperatures down. Make sure that the soil is mulched to reduce evaporation, and water well to make sure water needs are met and to create cooler soil and air temperatures.

6. Damping Off

If your seedlings germinated, but perhaps patchily, and soon after wilted and died, you may be experiencing a problem called ‘damping off’.

Damping off is a problem that can affect most seedlings. Pre-emergence damping off will mean that seedlings fail to emerge at all. Post-emergence damping off will cause seedlings to collapse some time after germination.

It is a problem seen most often when sowing early indoors or in a greenhouse. It is most damaging in the spring when light levels and temperatures are low, and humidity can often be high. This is because seeds grow most slowly at that time. However, it can occur at any time of year.

Damping off is caused by a number of different soil-borne fungi and fungus-like organisms. These include Pythium, Phytophthora, Rhizoctonia and Fusarium.

These attack the seedlings just after germination and cause them to collapse and decay. You may see a white mold around affected seedlings, which is a give away that this is the problem.

White mold around seedling is a sign of “Damping off”.

How To Reduce The Chances of Damping Off

If you are growing your seeds in commercial compost, the fungus should not be present in your growing medium. If you are growing in home-made compost, it may have been the source of the damping off organisms.

If this is a recurrent problem with your home-made compost, you can consider using steam to sterilize the mix and destroy pathogens. However, this is rarely required and most people will have no problems using their own compost.

If you are using rainwater to water your plants, the organisms may have come from there. Make sure your water butts and containers are all clean, and sealed to stop organic material from getting in. With mains water, this should not be an issue.

Make sure your trays, pots and containers are all clean before you use them. And if damping off has been a problem, do not reuse those containers. Maintain good hygiene and carefully dispose of affected material well away from your garden growing areas and compost heap.

Sow your seeds thinly to avoid overcrowding, which can make it more likely for damping off to occur again. Don’t overwater. Make sure that the seed growing area also has good ventilation and airflow, to reduce humidity.

Why Seeds Aren’t Germinating When Environmental Conditions Are Right

Sometimes, you might be convinced that the environmental conditions were perfect. Damping off was not the problem. So what went wrong? Here are a few more reasons your seeds aren’t germinating:

7. Low Germination Rates Are Normal For the Seeds You Are Attempting to Grow

It is a fact of life that some seeds naturally have a higher germination rate than others. With any seeds, it is common for a certain proportion to fail.

For some particular species, however, you may find that only half of the seeds germinate – or even fewer. This may be due to a problem. But it could also be the case that seed germination rates are usually low for the seeds you are attempting to grow.

Check seed packets and information online or in books to see whether the results are normal for the plants you are trying to grow before immediately jumping to the conclusion that something is wrong.

8. Seeds Were Stored Incorrectly

Another reason why your seeds aren’t germinating might be that they are no longer viable. Unfortunately, seeds can lose their viability if they are not stored correctly.

For example, if your seeds were stored somewhere with temperatures that were too high, this could be the problem. They may also have been exposed to high temperatures or other environmental hazards in transit to a garden centre, to a store, or to your home.

Unfortunately, if this is the case, the seeds will not germinate at all and are no longer any good. They may have been damaged enough that they can no longer mature into healthy plants.

9. The Seeds Are Simply Too Old

It is also important to realise that seeds do have a ‘use by’ date. It may simply be that the seeds you are trying to germinate are simply too old. Seeds are only viable for a certain time period, and some will lose their viability more speedily than others.

Carrots and parsnips, for example, are amongst those seeds that lose viability at a quicker pace. Of course this means that it is important to plant your seeds in time.

Aim to plant seeds from these plants, and others that lose viability quickly, within a year. Alternatively, collect or buy these seeds afresh each year.

Seeds packets often come with a ‘sow by’ date on them. This is not a hard deadline and some seeds may still germinate after the date given. But sowing seeds after this date will often lead to lower rates of germination.

If you are saving your own seed, be sure to mark containers with the date when you collected them, so you know when to use them.

10. Seeds Were Eaten Before Germination Could Occur

If no seedlings have appeared at all, there is one final potential answer to this puzzle. If you sowed seeds outside or in an open greenhouse or polytunnel, something may have eaten the seeds before they had a change to germinate!

Birds, rats, mice or voles are the likely culprits. Though it could also have been a number of other pests.

If you think that pests eating your seeds is the problem, you can increase your chances of avoiding this problem in future by sowing seeds inside your home, or on a hanging shelf in a polytunnel or greenhouse. You can also try to protect your seeds with a cloche, row cover or mesh.

In gardening, not everything always goes according to plan. But when you slowly work through the various options to find the source or sources of a problem, then seek solutions to each one in turn, you are sure to have plenty of great success stories. If at first you don’t succeed – try, try again!

Next Step – Prick Out Your Seedlings

Getting your seeds to germinate is only part of the puzzle. The next step may involve “pricking” them out into larger containers, or even into the ground.

Elizabeth Waddington is a writer, permaculture designer and green living consultant. She is a practical, hands-on gardener, with a background in philosophy: (an MA in English-Philosophy from St Andrews University). She has long had an interest in ecology, gardening and sustainability and is fascinated by how thought can generate action, and ideas can generate positive change. In 2014, she and her husband moved to their forever home in the country. She graduated from allotment gardening to organically managing 1/3 of an acre of land, including a mature fruit orchard,which she has turned into a productive forest garden. The yield from the garden is increasing year on year – rapidly approaching an annual weight in produce of almost 1 ton. She has filled the rest of the garden with a polytunnel, a vegetable patch, a herb garden, a wildlife pond, woodland areas and more. Since moving to the property she has also rescued many chickens from factory farms, keeping them for their eggs, and moved much closer to self-sufficiency. She has made many strides in attracting local wildlife and increasing biodiversity on the site. When she is not gardening, Elizabeth spends a lot of time working remotely on permaculture garden projects around the world. Amongst other things, she has designed private gardens in regions as diverse as Canada, Minnesota, Texas, the Arizona/California desert, and the Dominican Republic, commercial aquaponics schemes, food forests and community gardens in a wide range of global locations. In addition to designing gardens, Elizabeth also works in a consultancy capacity, offering ongoing support and training for gardeners and growers around the globe. She has created booklets and aided in the design of Food Kits to help gardeners to cool and warm climates to grow their own food, for example. She is undertaking ongoing work for NGO Somalia Dryland Solutions and a number of other non governmental organisations, and works as an environmental consultant for several sustainable companies. Visit her website here and follow along on her Facebook page here.