New to sowing seeds

Hi Folks,

I am new to gardening in general and have so far only sown one lot of biennials (canterbury bells).

So with brand new greenhouse and heating mat at the ready I have bought dozens of packs of seeds. 'Nearly' every packet tells you how long it will be to germination but none of them say how long they must remain in seed pots for after you have pricked them out.

Is there a general rule of thumb? Or do individual types of plant need different growing times? How do I find the information for each type of plant?

I ask because I'm trying to set up a schedule for myself for next year. I appeciate it can't be a strict schedule but I would like to try to work out what to sow when, when to pot on etc., so that plants actually end up in the garden for summer.

I would truly appeciate any help that can be given.

 

The most usual problem is planting too many seeds too close together, the roots get all tangled up and get damaged when you try and tease them apart. A better method is to grow two or three seeds in individual tiny pots or those cellular seed trays, transferring the seedlings to larger pots when the true leaves show. The first leaves are called cotyledons and are there to collect sunshine and help to grow the first true leaves. These will turn yellow and drop off in time - don't panic, it's normal.

Cheers, Tony.

 

I use 1/4 size seed trays, and I sow twice a month. Nearly everything will have germinated within the 14 days, and the trays can then come off the heated propagator - and make space for the next batch. I have extra trays though, as they may have germinated but won't be ready for pricking out. This is how I control my schedule for "sowing".

Some things either germinate slowly, or grow on slowly ... or both! They get started earlier - so that they will be a decent size by the time it comes to planting them out.

Conversely some things are very quick = in terms of Veg. then Runner beans, and Courgettes. I sow these as late as possible as they hate cold nights - so I don't want to plant out until well into May, and they only really need a few weeks from sowing to planting out.

So this leads to the Space Problem You sow early things in, say, February and late things up to, say, March ... and then in April everything is coming along nicely, but ALL are needing space!

Hardy plants can start to go outside to "harden off" - this aclimatises them to being outside - if you put them straight out the shock will knock them back several weeks - so they go out on nice days (warm, no wind - and in a sheltered position), and back in for the night. Gradually you leave them out for longer. Some hardy plants may be staying out all night from the start of March - so they will make space for other things, however none of the Tender half-hardy annuals will be able to stay out that early in the year.

I keep a notebook. It has the dates of Sowing, Germinating, Pricking out and Planting out. I use that to plan how long things actually take in practice. The seed packet will give you a good idea - if it says to sow in January/February then that will be a slow grower, whereas if it says to sow up to April (even if it says you CAN start in January) then its a faster grower.

For example: Petunia, Lobellia take ages to get big enough to prick out, and ages more to make big enough plants to plant out. They both have tiny seeds.

Ricinus (Castor Oil Plant) has huge seeds - size of Runner beans - they germinate quickly, and grow like blue-blazes - and they make plants that are 6' tall, or more, in a single season.

So seed size is another yardstick.

You could post your list of seeds here and I'ms ure folk will have suggestions on Early/Mid/Late sowing times

 

Hi Kristen,

Thanks for your detailed response.

I don't have any electricity in the greenhouse and have extremely limited space in my home. In fact just enough space to put a large heated mat (and I'm going to have to remove the microwave in order to do that. The heated mat has room for 5 normal sized trays. Once they come off the mat the only space I have is the kitchen windowsill which faces west and again space for just five trays. Hence the reason for wanting to find timings for how long things will take.

I am presuming that I won't be able to move things to the greenhouse until sometime in may (although I do have some annuals that can go straight into the greenhouse). I thought that if I find out the timings I would be able to choose which to do first.

The list is .....

The ones I think will have to be germinated indoors?
gazinias
rudbeckia
geraniums
busy lizzie
poached egg plant
Aubrieta
Coleus
Marigold
verbena

The ones I think I can sow in the greenhouse
lavender
impatiens
Lobelia
Petunia
Anagallis
Tagetes
nasturtium

One thing that does confuse me is I have lobellia and petunia from two different places and each pack gives the opposite instructions!

 

You could do pretty much what I do then

5 trays on the heated mat. As soon as they germinate move them to the windowsill. It is important that they have good light once germinated; put a sheet of something reflective behind them; flat white (like polystyrene or a piece of hardboard painted white) is better than cooking foil, but cooking foil (taped to half-an-old-cardboard-box would do)

And then from Windowsill to being pricked out

If you sow 5 trays each fortnight that gives you about a month's time in the house (once any in the second batch on the heated mat germinate they will evict something from the windowsill!)

Once they are big enough they need to be pricked out. You won't have space for them indoors once they are pricked out, and you may not have space for them before then - once you get to 5 trays on the windowsill. The trays can go in the greenhouse, instead of the windowsill, once they've germinated ... but ... the greenhouse must be warm enough for them.

For anything hardy they will be happy in the greenhouse, for anything half-hardy they really need minimum of 10C at night, although they may survive lower than that they are likely to "stall" or be stressed due to cold, and that incourages infections and poor quality plants later on.

germinate

Depends a bit what part of the country you are in (if you put your "location" in your Profile it will show up under your avatar on the left, which will help ) but in general you should be fine with things in the greenhouse in April - but you might need to be prepared to bring them in for the night if it turns cold - they won't need light, at night, so could be on utility room floor or something like that - its only for a few weeks or you'll need a greenhouse heater just for the few cold nights

Marigold and Tagetes (below) same thing? Both half-hardy?

Not sure about Verbena, I think that is hardy so maybe that could be in greenhouse (once germinated)?

impatiens same as busy lizzie above (half hardy)?

I think the Lobelia & Petunia are half-hardy and will need to be indoors

I don't know about Anagallis

Seed companies rarely (if ever?!) update the instructions on their seed packets, so if wrong etc. they stay that way.

If they are Half-hardy you need to start them off indoors (or wait and sow them quite a bit later in greenhouse). If the seed is small (or you know that they are "slow") then I think they need to be indoors too so the get a "wiggle" on - and start flowering nice and early

I don't do many annuals, so others may have better advice on when/where to start those off.

 

Hi Kristen,
Thanks once again - you are so good at answering questions.

I think I'm going to have to face the fact that I can only do about half of what I wanted to do .... or even (if this is possible) start the perennials late - do you think that would be ok?

 

How many plants do you need? I often grow two varieties in a single 1/4 sized seed tray (it helps if you know that the two varieties will need pricking out at the same time, otherwise you run the risk of disturbing the "slower" ones when you prick out the "faster" ones.

Here's my (2 varieties of) Coleus in the middle of March - I grew between 100 and 150 Coleus plants this year. However, best not to crowd the seedlings, because it can encourage damping-off fungal disease, but hopefully you don't need 100 Coleus plants?!


but maybe you can "double up" if you only need modest quantities ?

 

Hi Kristen,
Oooooo, I had presumed that each packet of seeds would require a tray. It never once occured to me that I could put more than one pack into a tray. Food for thought!