PLANNING the gardening year ahead is fun and rewarding, the best way to spend a cold, wet or snowy January afternoon.

But when can you start sowing? Outdoors, seeds will just rot before the soil warms in late March or April. A heated propagator and greenhouse let you start earlier but after quickly germinating seedlings grow slowly until light levels and overall temperatures improve.

But sow too late and you could miss the boat. Sowing leeks, tomatoes or peppers in May is pointless as they won’t have time to reach maturity. I’ll focus here on vegetable seeds to start in late February and March.

You can’t afford to waste space on poorly performing varieties when you devote a large area to them. Since my leeks merit a 10m2 bed in my kitchen garden and will hog it for most of the year, I must choose some reliable varieties: plants that don’t readily bolt - run to seed, will cope with a harsh winter, and produce fine big specimens for the kitchen.

Everyone wants to stick with well-kent winners, but new varieties appear every year, so I’m all for devoting a little space for one or two punts. And I confess some of my long-time stalwart leeks haven’t done well this year. Unusually, they’ve already started bolting and producing slimy outer leaves.

I’m struggling to understand why this should be, so, as I suggested a fortnight ago, I’ll blame the erratic weather. The very cold early winter spell was followed by much milder, wetter ‘climate change’ conditions. Is that the key? Were plants fooled into thinking winter was over and it was time to flower? And though ‘hardy’ plants cope with very cold, dry weather, they hate the wet.

So if last year’s leeks are doing badly, it’s time to find replacements. So my thanks to Gardening Which? for conducting a leek trial in 2020. They found that ‘Lyon Prizetaker’ a 19th Century heritage variety and ‘Malabat’ performed extremely well. Guess what I’ll be trying this year.

Like leeks, tomatoes grow slowly so need sowing in early March. With limited greenhouse space, I always need to maximise the returns.

As with most vegetables, the seemingly endless list of tomato varieties increases every year. It includes ones with some resistance to late potato blight, Phytophthora infestans, a devastating fungus-like disease for tomatoes.

So look out for tomatoes with ‘resistance to’ or ‘tolerance of’ blight. These include the cordon cherry tomato ‘Berry’ and cordon ‘Fandango’. Resistant varieties decrease, but don’t eliminate, the risk.

The further north you live, the quicker a crop must grow, and with tomatoes, the smaller the plant and its fruit the faster it ripens. ‘Tumbling Tom’ a small plant producing cherry tomatoes will be speediest, followed by bush, standard cordon and beefsteak.

This also applies to lettuces, a popular early sowing plant. Loose leaf and cut and come again varieties are speediest, followed by butterhead, with fully hearted cos taking longest.

Look out for lettuces that are ‘very quick maturing’ or ‘early to mature’ and ones that ‘hold well without bolting’ giving a longer cutting period.

Try keeping to the ‘use by’ dates recommended by seedsmen. After this germination rates fall below 75%, as required by UK standards.

These standards include a variety’s ‘purity’, whereby seeds are 99% of what is claimed and parent plants are healthy and have not cross-pollinated. All this is in line with EU standards ensuring free trade within the bloc.

It’s anyone’s guess what will happen now, of course. Under the last minute trade deal the export of seed potatoes to the E.U. is prohibited and no decision has yet been taken on plants and seeds.

Plant of the week

Phlebodium aureus “Blue Star’ is a fern for growing indoors. Its long, deeply lobed fronds are a most attractive blue/green colour. Place the fern in bright light out of direct sun and keep it quite humid with misting.