Seeds sown a little bit early

I have sown around 100 mixed seeds including coleus, Dichondra, dahlia, sunflower, heartease and have around 95% germinated under lights at a steady 21/23 degrees. I am wondering if I have started a bit early would these be ok under lights in my shed for a few weeks if it’s still not quite warm enough. Would I need a heat mat or should small plants be strong enough to survive a little cold from the shed outside at 12 week stage?
Thank you for any advice
Craig

 

I would keep them on the heat. Worst case I would bring them in the house when there is a chance of frost. Coleus will not stand frost - I cant speak for the other plants. How big are the seedlings ?

Tempting as it is, its a bit early for sowing a lot of seed yet. We could still get a hard frost for a couple of months

 

I think we are all tempted to sow early then struggle to stop the plants from growing too leggy. I probably do this each season if I'm honest

 

Hi,

You will need your lights on to stop them getting leggy partic as you have little natural light in a typical shed ( what type of lights are you using - leds ?)

Also think you need a minimum temp of 9 -10c to keep them growing at a reasonable rate.

No idea which end of the country you are, but most of those plants cannot be put outside until late April/ early May when the frosts have usually gone.

That means you have got to keep them indoors and growing for 3-4 months !

What you do find come May when planting out , it that sowing mid to late March will produce plants as big if not better than ones you started off now.
Also they are likey to be better plants as the ones you sow now are more than likely going to be checked in their growth at some point, which can them affect them as mature plants.

Also a bit surprised when you say mixed seeds, do you really mean they are all sown in one tray together ? how are you going to know whats what ?
Normally you keep them as separate species as they all tend to grow at different rates .

 

Just to add to my first post, and to contradict myself to a level.

I sowed a number of aeonium varieties late last year as they need a temperature around 18 degrees to germinate. These have been under grow lights for two months now and have only the heat of the wood burner in the outbuilding. Id say they are now between 5 and 20 degrees.

Ive also sown 5 varieties of Puya at the cold end of the polytunnel as they need a period of stratification before they will germinate.

 

The Sunflower will be a problem , its going to get far to big / leggy before it goes outside. I probably scrap the sunflowers and sow again late MArch /April

 

They have been growing under full spectrum LED grow lights which I will move out into shed, I will also invest in heat mats if necessary to get the best out of plants. I realise I have sown a bit early I am new to this it’s my first time having a go at growing from seeds.
Maybe I will sow some more in March as a comparison!

I am located on the border of scotland in Cumbria.

I Have them labelled and sown in separate trays, the Dichondra and coleus are for my summer displays and the sunflower, dahlia and heartsease my son grabbed from garden center as he wanted to have a go and get involved with me .

 

I was thinking that myself that’s no big deal really thanks for your input

 

In terms of stopping them becoming too leggy, how have you found the best approach with seeds sown to early to reduce this?

 

The seedlings have literally just germinated so won’t even be thinking of putting them out into shed until beginning of April

 

I used to sow seed far too early, I've never used lights and only really think they work when used with more unusual plants, maybe those that come from the tropics and are likely to be grown as pot plants for many years.

Summer bedding, apart from a very few types are best sown from early March, for the slower ones, to even May for the fast growers.

Never found anything to be gained by sowing bedding plants too early, they just get too big, out grow their pots, get starved, start to flower, and tend not to do well when finally planted out in May, that could be June in Cumbria, thats 5 months away

 

Oh well I guess it’s a case of suck it and see what happens!

 

Hi,

Well you can never knock beginners enthusiasm so do carry on trying to raise those seedlings, it will be a valuable exercise for the future.

One way to control them as they grow is to pick out the growing tips when they seem to be getting too tall or leggy, this will make them put out side shoots and bushier plant.

Would suggest you also prepare to do a late March sowing of the same seeds so you will be sure to have something to plant out in May.

There are a few seeds you can start off now, that do not need lots of heat once germiated, just sown some Sweet Peas and Leeks myself.

 

As I said, I used to sow seeds far too early, so impatient in those days.
Now sometimes I do it too late

 

Grow lights are going to help but the best way to stop them being leggy is to sow later. I know that's not what you asked but I think we've all been guilty of sowing too early at some point and struggled with providing sufficient light.
You can nip the tops out of some plants to encourage them to bush out but other plants (eg. your sunflower) you cant do this with.
Use the instructions on the seed packets as a guide. If using heat, sow at the early end of the suggested sow time.