Indoor Sow vs. Direct Sow

[Glassonion91168]

Hi all,

I was curious if it matters whether you indoor sow or direct sow. I imagine it depends on what you're growing. My frost free date says April 30, but I think that's a bit early. Here's what I plan on growing this year:

Moonflowers
Morning Glories
Zinnias
Coleus
Sunflowers
Marigolds
Tomatoes (endless summer and plum)
Maybe watermelon

As a preference, I like indoor sowing because it makes me happy, but if it's better to direct sow then I can deal.

Thanks for any and all help!

[rainbowgardener]

Moonflowers
Morning Glories
Zinnias
Coleus
Sunflowers
Marigolds
Tomatoes (endless summer and plum)
Maybe watermelon

It does make a difference what it is. Of your list I would start indoors: moonflower, coleus, marigolds, tomatoes. I would direct sow in the ground morning glory, zinnia, sunflower, watermelon.

For me part of the deciding is how quick they are to germinate and then to grow. The longer it takes the seed to germinate, the more bad stuff can happen while it is sitting in the ground waiting- too much rain waterlogging it, too little rain drying it out, etc. It is easier to provide the constant good conditions indoors. The moonflowers are difficult to germinate, need to be scarified and then soaked and kept moist. The tomatoes take 4 months from seed to ripe tomatoes. If you don't give them a head start indoors, you won't have a very long productive season before fall frost ends them. Marigolds are a bit slow sprouting and growing for me and I like to have them ready in bloom to pop in when I am planting the other stuff.

Things like the zinnia, sunflower, watermelon, if you just wait until the soil is well warmed up, they sprout and grow very quickly and don't really need the head start.

[skiingjeff]

While I agree with RBG, I also indoor start my giant sunflowers. I know it not really necessary but since they are the giant annual sunflowers, I like to give them a little head start. By the time I plant them outside, they have two sets of leaves or so.

Maybe it just my wanting to start everything because I can't wait!

[imafan26]

People who have to worry about the sudden temperature drops and who have short seasons need to make the most of the time they have so indoor seeding really helps.

Besides what Rainbow said about fast and slow growing crops, you need to also consider how easy or difficult things are to transplant. Dill, carrots, parsley have tap roots and while they can be transplanted if you are careful, they are better sown and thinned.

Some things like peppers, tomatoes, and eggplant like a warm soil and not a lot of rain. To get a head start on them, it is better to grow them indoors with a heat mat to get the soil temp up to around 70 degrees.
I can start tomatoes outdoors in cooler weather but the rain will cause problems with dampening off and fungal disease. Peppers and Eggplant won't germinate well unless the temperatures are at least 65 degrees at night and they also have problems with fungal disease, and rot when there is too much rain.

[Glassonion91168]

Wow, thanks everyone for all of the great tips! I think I will try direct sowing the zinnias et al this year. I decided that 5/17 is a good day to plant everything, including the ones I'll have started indoors.

I think I'm most worried about when to start my tomatoes indoors. The packet says 6-8 weeks, so the earliest I would start would be around 3/20. I wonder if I should even start them around 2/20 just so they're a little heartier when I transplant on 5/17.

Again, thank you!

[rainbowgardener]

No, earlier is not better for tomatoes! My 8 wks ahead of average last frost date is right about Valentine's day, so that's when I was planting tomatoes indoors. One year I decided if early is good, maybe earlier is better and planted in late January. The plants got really big and needed to be up-potted again. Then I didn't have room for them under my lights any more, so I tried putting them on window sills. Within just hours (it seemed like) of being there, they got immensely tall and skinny and leggy from not enough light. Some people don't think that is so bad for tomatoes, because you could just bury all that extra stem. But my experience was being tall and skinny and top heavy, the least wind or just moving them around, bringing them in and out to harden off, those stems just snapped. It was mostly a loss.

Unless you can pot up to large pots (at least 6" deep and diameter) and then still have room to keep big plants in pots that size under your lights, I wouldn't advise starting any earlier than 8 weeks. I have since moved to 6 or 7 weeks.

[applestar]

I wouldn't recommend starting tomatoes 2/20 if they are going to be planted mid May... Unless you have only small number of plants, you have plenty of space and supplemental light set up for growing plants, and you plan to uppot them and growing in 1-2 gallon containers by that time, and feel confident about transplanting 18" to 2 FT tall gangly, easy to break tomato plants.

I'd say don't start any earlier than 3/1 and you *may* barely be able to get away with uppotting in in 24 oz - 32 oz containers and planning to take them outside/inside morning/evening towards the end (been there, done that)

[Glassonion91168]

My plan is to start them indoors then plant them directly into the ground, about 8 inches deep once they’ve grown a little. I did that last year and it worked out beautifully. Last year I started them indoors in January and despite being quite lanky and long they did great planted 8 inches deep. But I did plant them in July because I just didn’t know any better and it was my first time. I'm eager to start, but I want to make sure I don't start too early.

Thanks all!

[rainbowgardener]

You slowed down the development of your tomato plants quite a lot by keeping them indoors under lights, presumably in fairly small pots, all that time. If you had planted them in the ground in May as soon as danger of frost is past for you, by July they would have been huge with fruit on them. You were bonsai-ing your tomato plants!

[Glassonion91168]

You slowed down the development of your tomato plants quite a lot by keeping them indoors under lights, presumably in fairly small pots, all that time. If you had planted them in the ground in May as soon as danger of frost is past for you, by July they would have been huge with fruit on them. You were bonsai-ing your tomato plants!

I did keep them in small pots on a heating mat after they were too big for the peat pellets. I had them growing in my bedroom next to the window. It's really the only place in my house that gets the best lighting. Do you think starting in March indoors in the same conditions as last year then planting deep in the ground in May will work? Or should I start in February if I plan on planting them deep, just because they might be a little heartier?

[applestar]

I'm going to quibble about your use of the word "heartier"

The plants may be "taller" "lanky-er" but probably "paler" "thinner" "weaker" ...and not really "heartier"

You want adjectives like "stockier" "stronger" "healthier"

You said you kept them on heating mats -- tomato seedlings grow stockier grown cool in 50's to 60's°F. Especially when light is insufficient. They develop more dense root systems and stronger/larger (heartier? ) leaves when uppotted at least once in fertile growing medium midway/a month before planting out. In larger containers with sufficient growing medium as buffer, they will be able to withstand going outside when temperature/weather is favorable and for increasing durations, growing sturdier and being well hardened off by the time they can be planted in their final location.

They can be planted deep -- I always plant tomatoes deeper, though this year, I'm also going to try laying some on their sides as well. Last year, I compromised between deep cold root zone vs. shallow warmer but more likely to dry out trench by planting at an angle (I left the seedling tray tilted while hardening off to get them to grow at an angle -- I recently saw someone post that laying the seedlings on their sides for a few days will make it easier to plant sideways in a shallow trench.)

[Glassonion91168]

Thanks for the grammar tips, lol! I think once they're too big for the peat pellets I'll transfer them to the 5 inch pots while still on the heating mat. Then I'll keep them under a large clear plastic tub outside a week before they're due to be planted. Sound good?

[rainbowgardener]

You are not quite getting it. They will do better for you with less pampering. So yes, pellets to 5" pots to ground is great. But get the heat mat out from under the 5" pots, they neither need nor benefit from the heat at that point. Then when you are taking them outside, don't put the tub over them. To start with an unvented tub like that on a clear sunny day can totally cook your plant quite rapidly, even though it is cold out. And you want your plant to get toughened to the outside conditions. So of course, you don't start this until temps are well above freezing (like in the 40's) and you will start with small, protected exposures, keeping them out of the wind. With a week to 10 days or so of graduated exposures, they will be ready to live in the real world, assuming weather cooperates (sudden cold snaps can require bringing them back in or covering them at night if they are planted).

[Glassonion91168]

Makes a lot of sense. Thanks!