With Easter upon us, spring may even be round the corner, so seed sowing is a priority. If, like me, you’ve a drawerful of old seed packets, check when they were first packed as some stay viable for longer than others.

But none could rival the famous seed from an Israeli date palm. Excavated during an archaeological dig in 2004, the 2,000-year-old seed was planted for fun and has now become the world’s most famous palm.

But other species, such as hepaticas and the fashionable vegetable Salsola soda or agretti, scarcely survive a year. Parsnips and anemome nemorosa are nearly as

short-lived but brassicas and peas stay viable for many years.

Every seed needs the right moisture, light and temperature and, given these conditions, strange things can happen. After a Second World War air raid on the British Museum’s botanical department, seeds of a silk tree collected from China in 1791 burst into life. The heat of the fire and the firemen’s hose did the trick.

We can be more precise in our seed sowing than that. Tomato and pepper seed need 20C to germinate successfully, while 7-10C works for our native broad beans and cabbages.

Quick-growing seedlings thrive and elude pathogens, so I find a propagator comes into its own, especially for very early sowings, when slow-growing seedlings become a target for every passing fust.

And moisture levels are equally important. With some – but not too much – water, dry seed starts swelling. Seeds also need oxygen and that is lacking in waterlogged compost, which can cause poor germination and growth.

Most of us use fine textured seed sowing compost that contains some nutrient. If, like me, you make your own, using

home-made compost and leafmould or coir, mix them to an equally fine tilth. A Rotasieve is excellent for this.

Very fine compost surrounds seed with moisture and tiny air pores, but the woody chips in rougher compost create large dry air holes.

Fill a seed tray and firmly tamp down the compost. I put a handle on a piece of hardboard, cut to sit inside the tray and have tampers for every size of tray. Then, before sowing, water with a fine rose. Sow very thinly and cover with compost.

Don’t make the classic mistake of watering after filling the tray. The force of the water may drive some seed further into the compost, so seed grows unevenly.

More importantly, by watering before sowing, the seed lies on essential moisture and, initially, the compost cover acts as mulch and prevents evaporation.

These trays are only suitable for small seed when a thin covering is all that’s required. Some dust-like seed, such as nicotianas, shouldn’t even be covered.

With larger seed, use small pots or root trainers, ensuring that the seed is sunk to twice its diameter. Again, water, then sow and cover with compost. Use this method when sowing directly in the open ground.

Seed species respond very differently to light. Some Arctic mustards seemingly detect changing light levels beneath 2metres of hard packed snow.

Other species can only germinate in the dark, while tiny seed must be completely exposed to sunlight.

Breaking my general rule, I water foxgloves after sowing. I firmly tamp down the soil, sow very thinly on the soil surface, and then water.

Poppies, on the other hand, should be just covered with soil. So tamp, water, sow and lightly cover.

The fragile shoots of these surface huggers must quickly reach the light, whereas the robust shoots of runner and broad beans are designed to push up through denser, darker soil.

Plant of the week

Primula ‘Dark Rosaleen’

Not one to hide her light under a bushel, Dark Rosaleen’s bright

pink flowers are also prettily

striped.