9. Circulate the air.
Circulating air helps prevents disease and encourages the development of strong stems. Run a gentle fan near seedlings to create air movement. Keep the fan a distance away from the seedlings to avoid blasting them directly.
1. Choose a container.
Here are the basics in 10 steps.
Start feeding your seedlings after they develop their second set of true leaves, applying a half-strength liquid fertilizer weekly. Apply it gently so seedlings are not dislodged from the soil. After four weeks, apply full-strength liquid fertilizer every other week until transplanting.
Maybe you want grow plants from seeds to save money. It’s definitely cheaper than buying transplants. It will also be easier to find seeds of varieties not typically available for sale as transplants. Whatever the reason, starting plants from seeds is probably not a hard as you think. And growing plants all the way from seed to maturity is one of gardening’s most rewarding endeavors.
5. Maintain consistent moisture.
Prior to germination, cover your container to help trap moisture inside. Seed-starting kits typically come with a plastic cover. You can also use a plastic bag, but it should be supported so it doesn’t lay flat on the soil. Remove covers as soon as seeds sprout. Once seedlings are growing, reduce watering so soil partially drys, but don’t let them wilt.
3. Plant at the proper depth.
You’ll find the proper planting depth on the seed packet. The general rule of thumb is to cover seeds with soil equal to three times their thickness – but be sure to read the seed packet planting instructions carefully. Some seeds, including certain lettuces and snapdragons, need light to germinate and should rest on the soil surface but still be in good contact with moist soil. Gentle tamping after sowing will help. After planting your seeds, use a spray bottle to wet the soil again.
Seedlings need a lot of light to grow into sturdy, healthy plants. No matter what anyone tells you, chances are that you do not have enough natural light in your home to grow robust seedlings. Even a south-facing window usually will not do. You can, however, use artificial light to achieve the right amount of light required by seedlings. To do so, obtain grow lights explicitly designed for plants. Or, for a more economical solution, purchase large fluorescent shop lights outfitted with one warm bulb and one cool bulb.
The Spruce / K. Dave
Watch Now: Mistakes to Avoid When Growing Seeds Indoors
When your seedlings are large enough to plant outdoors, you need to prepare them for the transition by hardening off. Hardening off gradually prepares them for outdoor conditions like wind, rain, and sun. The hardening-off process is simple, though it can be time-consuming; it involves exposing your plants to the elements gradually. The first day of hardening off, place your seedlings outdoors for one hour, and then bring them back indoors. Gradually increase the amount of outdoor time every day for 6 to 10 days. You will need to make some judgment calls based on the outdoor temperature and the fragility of your seedlings. If it is a particularly cool day or very rainy, you will want to decrease the time of that hardening-off session.
There is no benefit to a tough-love approach with seedlings when they are young. They will either instantly die or become weak and then fail to thrive. Even the most stalwart plants, when young, need a considerable amount of coddling and attention.
The amount of water you supply can make or break seedling growth. Watering is one of the most challenging aspects of seed starting. Because seedlings are so delicate, there is very little room for error when it comes to watering. You must keep the sterile seed-starting medium damp but not wet.
Examples of suitable kinds include Ammi majus and Ammi visnaga, Orlaya grandiflora, varieties of Scabiosa grandiflora, Nigella and sweet pea. Recommended seed suppliers include all good garden centres, as well as the Galway-based online specialist seed suppliers Seedaholic (seedaholic.com).
So if you’ve spent the past few weeks staring with increasing frustration at your freshly-sown seed trays/pots for any tiny sign of life, then this column is for you. Because I know all too well that bitter sense of disappointment when nothing – nothing! – emerges, as well as the pure, delicious delight when it does. Here’s what I’ve learned . . .
As a general rule, seeds of most plant species require the darkness provided by a shallow covering of seed compost or vermiculite for successful germination. But some (usually the tiniest seeds) need exposure to light to trigger germination so should be surface-sown. Examples include the seed of foxgloves, nicotiana and antirrhinum. Once they germinate, all seedlings require high levels of natural light for strong healthy growth – a very good reason not to sow too early.
To germinate, seed must be viable, meaning it must be alive/respiring. But as seeds age, their viability dwindles, especially if poorly stored (the best place to keep them is in an airtight container placed in the vegetable tray of the fridge). For this reason, even the “sow by” date on the packet isn’t always an accurate guide. Confusingly, the seed of some species can remain viable for many years while others quickly deteriorate. There are also plants – for example primula, astrantia, hellebore – whose seed must be sown freshly harvested.
Yet the simple truth is that it’s got very little to do with luck and instead a whole lot more to do with dodging some common pitfalls and following a few immutable rules of horticulture.
A good quality, fine-grade seed compost makes a huge difference. Klasmann does an excellent peat-free option (available from fruithillfarm.com), or, if you can’t get your hands on that, try Westland’s Seed and Cutting Compost.
Sowing seed too deeply is a classic beginner’s mistake, as is sowing too densely, which results in spindly seedlings competing for space and light. So try to space seeds evenly, thinly and to the depth recommended on the packet.