Hardening off seedlings

Tiffany Daneff / 14 May 2015

Gardening editor Tiffany Daneff shares her tips for hardening off seedlings grown indoors and puts some new compost accelerator and an aerator to the test.



There’s a lot going on this week what with my new compost aerator and accelerator turning up, of which more below. But it’s the windowsill seedlings that are taking up most of my attention.

So far I have sown Cavolo Nero, French Beans, lettuce and tomato Sungold and with all the sun they have come on nicely. So far, so good. However my difficulties always arise with hardening off. In the past I haven’t given the process enough time with sometimes disastrous results. This year, though, I’ve been mugging up.

In Mark Diacono’s latest book The New Kitchen Garden, £25, Saltyard Books, he recommends taking it slow and easy, allowing a couple of weeks for the seedlings to acclimatise from the cosy warmth of the kitchen windowsill to the tilting rains and full on breezes of Northamptonshire.

Mark’s hardening off system:

1. Put them outside for a few hours at the middle of the day. Then bring them back indoors.
2. Next put them outside for a whole day, and back inside at night.
3. Leave them outside for the day and covered with horticultural fleece at night.
Allow a couple of weeks for the whole process, giving each stage a few days before moving on.

Now I am mid way through the process and have a few points to add:

1. Watch out for cold winds. This will upset delicate leaves that may well shrivel in shock. (Er, just what’s happened to my beans but they survived the ordeal.)
2. Also keep an eye out for bright sun which can give quite a shock to the system too.

It seems counterintuitive but many lettuces really are much tougher than they look, the butterheads I prefer being a good example. Hence, despite the fact that we can still expect to get night frosts until early June here, I have planted out a few lettuce seedlings. This is more as an experiment than because I am particularly bolshy.

I have also planted out some of the kale (Cavolo Nero). Some are under a wire cloche (as I am worried the woodpigeons might snaffle them). The others are uncovered, also in an experimental kind of way. The thing about gardening is that every garden is different and you only find out what works by a process of trial and error – which, inevitably, involves more error than I might wish.

I shall report back on how the little critters progress.

The compost heaps

Back to the compost kit… I have a three bin compost system, with one bin for rougher stuff that will take longer to break down; a current bin into which go lawn clippings, cardboard and the kitchen scraps. The third is the compost that was made last year and is waiting to be used.

In London our bin was wriggling with worms but here there are terribly few. I don’t know if this really matters nor can I be sure if that is slowing down the rotting process. However when I saw Burgon and Ball’s new aerator I was intrigued.

Usually I turn the compost with a fork but that can be hard work on the neck and shoulders. The aerator is designed like a corkscrew so involves virtually no heaving of soil. I’ve been using it a couple of days now along with their Organic Compost Accelerator granules. These consist of blood meal, seaweed, garden lime, feather meal, rock phosphate and beet wine.

I’ll let you know how I get on with these but, if you want to, you will find more in the meantime at burgonandball.com

Stop press

One of my favourite organisations, Plant Heritage, which works to support the conservation and propagation of cultivated plants in Britain, is looking for some new trustees. They are hoping to find people with experience in a number of areas such as fund raising, marketing, the horticultural trade or even in IT. If you think you might be the kind of person they need you can find out more by following this link.

Or, if you would simply like to volunteer to help they welcome volunteers in a number of areas from administration, to project work, to PR! Do contact them if you would like to help: info@plantheritage.org.uk or ring 01483 447540.

The opinions expressed are those of the author and are not held by Saga unless specifically stated.

The material is for general information only and does not constitute investment, tax, legal, medical or other form of advice. You should not rely on this information to make (or refrain from making) any decisions. Always obtain independent, professional advice for your own particular situation.