Steps and tips to caring for seedlings six weeks after starting them from seed indoors, including how to harden them off for planting, if needed.
You can find more seed starting information in our Seed Starting Guide.
For this part of our Vegetable 101 Series, I wanted to share about what you can expect your seedlings to look like six weeks after planting them, how to care for them, and how to get them ready for planting in the garden.
This can be a crucial time – and to be honest, it’s when I’ve most felt like throwing in the towel and just buying the seedlings at times. Why?
- Sometimes they don’t look very healthy.
- Sometimes I’ve lost a few seedlings.
- Sometimes during hardening off, I’ve forgotten them outside all night.
- Most of the time my excitement over starting the seeds is waning (yes, even bloggers don’t always ‘feel’ it!).
But here’s where I encourage you with what I’ve learned:
With just a little care, your seedlings, no matter what they look like, can grow and will produce food (or flowers) for you and your family.
And it’s a wonderful feeling to have grown that vegetable from seed to sitting on your table, right?
So at six weeks, what does caring for seedlings look like? Basically one of three things:
- Repot, if needed, and stake any warm-weather seedlings like tomatoes and peppers that will stay indoors for awhile longer.
- Fertilize the warm-weather seedlings.
- Harden off cool-weather seedlings (lettuce, onions, broccoli, etc.).
Caring for Seedlings at 6 Weeks: Warm Weather Crops
1. Your pepper and tomato starts will be between 2-inches (some of the slow-growing peppers) and a foot or more (the indeterminate tomatoes).
2. Depending on the size of pots you started your seeds in, you will probably need to repot some (or all) of the seedlings to larger 4-inch pots.
This is especially true if you used the 6-cell pots in the seedling trays. They’re great for saving space and starting a lot of plants, but the longer growing warm-weather seedlings will need more room for their roots to grow.
3. In order to provide light as close as possible to the plants, your shop/grow light may look like mine: I just raise one side of the shop light to fit the tallest seedlings, in order to let the lower side still be closer to the smaller seedlings.
It’s not that pretty, but need outweighs looks in this case! The peppers are to the left, tomatoes on the right.
4. The seedlings will need another application of diluted fish emulsion fertilizer, but other than that, it’s just continuing with consistent watering and light until they are hardened off (see more on this below) and planted out according to the timeline in your area.
For me, it’s best to plant tomatoes around the first week of May here in the central Willamette Valley. I usually wait until June – and then using a pepper house – for peppers since they’re really susceptible to nighttime temps under 50 degrees.
Caring for Seedlings at 6 Weeks: Cool-Weather Crops
1. At the 5 to 6-week mark, your cool-weather crops – the tray shown above has onions, broccoli/cauliflower/cabbage and lettuces (right to left)– should look similar to the picture above. Fairly green and healthy-looking, not too overgrown or lanky and ready to be hardened off for a week or so before planting outside.
However, just a year or two later, I had seedlings that looked like this:
I’m not exactly sure why these seedlings grew so leggy – maybe the light wasn’t as close or I applied too much diluted fish fertilizer – but for whatever reason, they don’t look as healthy, do they?
But guess what?
I planted them anyway, used a row cover (best investment ever to early growth and keeping the bugs away!) and they grew and produced food for us. I think maybe a few of the cauliflower didn’t grow, but I find them to be touchy a lot of the time anyway.
The lesson? Plant anyway – as in all of life, the garden doesn’t have to be perfect!
2. Your cool-weather crops won’t need to be repotted, since they are going to be planted out soon, but they should remain consistently watered.
3. The biggest task at 6 weeks is to harden off:
How to Harden Off Seedlings
Definition: Hardening off plants is the process of preparing plants started indoors for the change in environmental conditions they will encounter when permanently moved outdoors.
So, those tender little seedlings you’ve been nurturing need to be “hardened off” because they have been in our nice warm houses and they would go into major shock if we just stuck them right in the ground to be battered by wind, rain, and cold.
Here’s the ideal steps to take to harden off your seedlings:
- Bring the tray of seedlings outside each day for about a week.
- Start them in a sheltered area, out of direct sunlight.
- Leave them out longer each time – but not overnight – starting with a couple hours and adding a 3-4 hours each day. Also gradually increase the amount of sunlight they have – but never direct for hours or they will cook in their little cells.
- Keep them consistently watered – it’s crucial. And they will use water more outside, so check them daily.
- By the end of the week they are ready to be outside all the time.
OK, that’s ideally. But sometimes this is what happens at my house:
- I leave them out for a couple of hours on day 1 in a shady area.
- I forget to take them out on day 2 until the afternoon around 3:00. Then I forget and leave them out overnight.
- When I go running out to check on them (they’re under cover on a table on the porch, so aren’t being pummeled by the rain), they look fine so I leave them, thinking I’d be going backwards to bring them back in now…
This still worked, believe it or not, and I was still able to use them mainly because they were are cool-weather loving plants. If I had done this with the peppers, I’d be buying my peppers at the nursery!
All this to say- life happens, but garden anyway!
Do you have any tips to hardening off your seedlings?
Next in the Caring for Seedlings part of the Vegetable 101 Series:
Note: Our classic vegetable gardening 101 series was published in the first year of the blog – 2009. It’s been republished with updated information and clearer formatting.