Raring to grow

After the recent cold weather it looks as though things may be getting a bit warmer this week. I will be glad to be able to do something outside, even though it may still be wet and cold. As I have said before, it is at this time of year that every flower, no matter how small, is especially welcome. Cold, frosty periods cause me anxiety as I look at my agapanthus and other slightly tender plants, wondering if they pull through. So those tough plants that not only survive but actually bloom now give me hope.

All of us are desperate to start gardening and sowing seeds seems like a good way to start. But beware of starting too early. A cold greenhouse is not going to be warm enough for most seeds right now. If you have a heated propagator you can ‘force’ seedlings to grow but then you have a problem when you take them out. The shock of being moved to a cold greenhouse will kill most of them and there is only so many plants you can have on the window sill in the lounge. Trying to keep seedlings ‘snug’ is not a good thing anyway – the lack of air circulation and high humidity is death to most seedlings. Light too is an issue. If the seedlings survive they will be tall and straggly as they try to reach the light.

So, all in all, it is best to wait till conditions are better for growth, before you sow. But for now, even though you may not be able to sow or get out to buy what you need, you can clean pots and trays and clean labels in preparation. When sowing indoors, it is important that your pots are clean and free from fungal disease so, on a mild day, fill a bucket with some detergent and warm water and clean your pots. Leave them to soak for a while and then scrub them, rinse and leave to dry before putting them away in the shed.


It is also important to only use clean, fresh compost for seed sowing. Old bags that have been left open over winter are not good for early sowings though, at a pinch, they can be used for later sowings of easy seeds and for filling patio pots.

One of the first seeds you could sow, if you are desperate to make a start, are onions. The biggest onions are sown in January but you really need a cool greenhouse to do well. But you could sow them on the windowsill and, as soon as they germinate, move them to a much lighter location, such as a cold greenhouse and then transplant them into cell trays as soon as their bent-over leaves (above) start to straighten.

Of course, we cannot get out to buy seeds as we usually would at this time of year. So can we use old seeds, left over from previous years?

My attitude is that, however old the seeds are they won’t germinate if they are left in their packets so it is always worth a go, however old they are. The problem is, of course, that you could waste time, compost and space in the propagator sowing old seeds and then find they don’t grow and you have missed two or three weeks growing a second batch. In practice, later sowings usually catch up because of the better growing conditions, but it can be annoying nurturing dead seeds. So here are some basics:

Unopened packs, as long as they have been kept in reasonable temperatures, will last at least a year longer than the sow-by date on the pack.

If packets have been opened they are still worth sowing the next year, as long as they have been kept cool and dry. When the inner seed packet is opened the seeds start to absorb moisture and to age. Seeds kept in a shed or garage outside may have got very hot in summer and very cold in winter and that is not good for them.

Keeping the seeds in an airtight container in a cool room indoors is best if the packs have been opened.

Some seeds last longer than you might think. Tomato seeds germinate well even if five years old. I have sown very old packs and had good results.

On the other hand carrots and parsnips, and parsley, have a short shelf life. Germination rates drop dramatically once the pack has been opened and it is best to sow fresh seeds every year. But if you have a pack, unopened, from last year, it will probably not be past its sow-by date and is worth a try.

Brassicas, such as cabbage and cauliflower last quite well and are worth sowing if old but you will find lower germination rates and a proportion of the seedlings will be distorted.

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