Brassicas - why transplant?

Many plants CAN be transplanted if necessary, enabling you to start things off indoors and so forth. However, for brassicas (pak choi, some kales and so forth excepted) it seems to be the consensus that you HAVE to start them off then transplant them. My question is - why? What is the benefit of the transplanting, or the negative consequence of simply sowing cabbage/brocolli and letting it grow in situ? Clearly the ancestral plant didn't get dug up and moved in the wild

8doubles has touched on some of these points, but I'd composed this and I'm darn well going to post it!!!

Firstly, forget about the ancestral plant. That's is not what we are growing.

There are many advantages to starting them off in pots/trays/nursery beds etc., not the least of which is the amount of space you have to look after whilst the seedling is growing. I would not relish trying to keep  a space weed free that is the size of my brussels sprout bed whilst waiting for 30 seed to pop through.

Then there's the quantity of seed needed. I hedge my bets and sow 40 seed to get 30 plants, invariably I get more. Then I can plant them exactly where needed. I dread to think how many I'd have to sow in the 3 rows that are full plot widths in order to do this once thinned out.

You simply cannot pop a solitary sprout seed straight into the ground where you ultimately want a plant and hope for the best.

Enough from me, someone else can carry on.

Plus transplanting pretty well always causes some root damage, ranging from slight to ohmigosh levels.  When the damage occurs the vegetative rsponse is to flood various plant hormones to the damage site to trigger rapid growth of both sealant tissue (equivalent to scab on schoolboy grazed knee) and replacement root tissue.  In practice the newly sprouted repair root is very often considerably stronger than the rest of the undamaged stuff.  I understand that this is the basis for the old boy trick of leaving seedlings on the path to suffer a bit before you plant them aiming for a bizarre "treat 'em mean and keep 'em keen" effect.

This flooding of vegetative hormones to the site of damage is the basis of rooting your cuttings too.

However I reckon really the main reason we all do it is for the reasons identified in the posts above!

Yes, but in a mechanised manner. It's plants they put in the fields for cabbage, caulis etc., not seed.

Nice to know that gardenaction agrees that transplants have better roots 

Plus, if you have club root then the bigger a 'clean' root ball the better.

I do that.


Mostly because I always forget to lime the bed!