Let’s cover the When for When & How to Start Vegetable Seeds
Below is a guide to know when you need to plant seeds indoors and sow them outdoors to get the best results for your vegetables and herbs.
* ALF= After Last Frost
*BLF= Before Last Frost
Indoors= Planting seeds indoors
Outdoors= Planting directly outdoors
When calculating your seed start dates add days to germinate to the start date for planting seeds indoors.
Germination dates vary quite a lot depending on the soil starting mix, the temperature indoors, the lighting, and the seeds you use.
|Basil||4-8 wks BLF||2-4 wks ALF||5-10 Days|
|Beans||Sow Direct||6-15 Days|
|Beets||3-4 wks BLF||8 wks BLF||5-20 Days|
|Cabbage||6 wks BLF||2 wks BLF||4-20 Days|
|Carrots||Sow Direct||7-21 Days|
|Cauliflower||8-10 wks BLF||2 wks BLF||4-10 Days|
|Cilantro||4-8 wks BLF||2 wks ALF||5-10 Days|
|Corn||Sow Direct||3-10 Days|
|Dill||Sow Direct||10-21 Days|
|Kale||3-6 wks BLF||2 wks ALF||4-10 Days|
|Lettuce||6-8 wks BLF||2 wks ALF||2-15 Days|
|Melon||4 wks ALF||4-10 Days|
|Okra||4-6 wks BLF||4 wks ALF||5-15 Days|
|Onions||10-16 wks BLF||4 wks ALF||7-28 Days|
|Peas||Sow Direct 2-4 weeks BLF||5-15 Days|
|Hot Peppers||4-8 wks BLF||3-4 wks ALF||14-30 Days|
|Sweet Peppers||4-8 wks BLF||3-4 wks ALF||7-15 Days|
|Spinach||8 wks BLF||2 wks ALF||5-20 Days|
|Squash||2 wks BLF||2-4 wks ALF||3-10 Days|
|Tomatoes||8-10 wks BLF||1-3 wks ALF||5-15 Days|
|Sweet Potatoes||Slips 2 wks ALF|
How to Start Seeds and Slips from When & How to Start Vegetable Seeds
Sweet Potatoes have special instructions to start them, if you are trying to start your own from a sweet potato you need to plant the sweet potato about 12-16 weeks before the last frost date.
place sweet potato in indoor potting mix and cover except for the very top of the potato, water regularly to keep the soil moist but not too wet.
Once you see the slip start to root after about 4 weeks monitor over the next 8 weeks to break off that root to place it in a jar of water to allow it to continue to grow before planting outdoors after the last frost.
If you are in the south you can plant directly in the ground, if you are in the north you will need to plant in a raised bed that has black plastic or weed barrier on top to heat up the soil in a southern-facing area. Black Pots are also good if they are large to give the plants room to produce potatoes.
In the north with cooler nights, you will need as long a season as possible to get sweet potatoes to produce a potato and not just leaves, the leaves are edible to use in salads.
What Seeds Need to Germinate
To get the highest germination % you want to give your seeds the best organic starting mix, I recommend Coco Coir, Black Gold, or Jiffy organic seed starting mix.
Since we have had very cold temperatures and I do not have my greenhouse setup with electricity yet I have moved my seed starts indoors to keep them warm for germination.
The trays that are made for starting seeds are not very strong and over time will leak, to get a much sturdier tray you should look at boot and shoe trays that are made with thick durable material that will hold up for years. This is a tray that I found at Home Depot that is 17 x 35.
The next item needed is seed starting trays with a dome.
Next, you will need grow lights to provide the correct type and amount of light needed to germinate and grow your seedlings.
I have provided two less expensive lights that you can use, but there are many you can choose from depending on how much you want to spend.
Once the seedlings start to grow you will need to provide a little liquid fertilizer to feed them as they grow.
The last item needed is plant labels to know what each seed is that you planted.
Now that you have everything to start your own seeds indoors you need to refer to the chart above to start planting your seeds based on the dates and germination times.
Planting and Caring for Your Seeds and Seedlings
Before you plant your seeds you should add water to your seed starting mix so that the soil will absorb water during the germination process.
Add starting mix to fill each cell or container 2/3 the way full, before planting seeds and additional starter mix. Read planting details to know how deep to plant each seed, I recommend you plant more than one seed in each cell to be sure you get a plant starting since you will not get 100% germination.
You may need to thin some of the starts if most or all the seeds germinate.
Once you plant the seeds, you need to cover them with the dome to keep the humidity higher until the plant’s sprouts appear. Once they appear you can remove the dome.
Some seeds need additional heat from a heating pad to help them germinate, one example is peppers. You will only need to apply the heat pad until they have germinated as long as the area they are in is warm.
Your plants will need 14-16 hours of light from your grow lights to provide them with the correct amount of light to grow.
As the plants grow you will need to raise the lights to keep the lights 2-4 inches above the canopy of the plants.
It is a good idea to either fan the seedlings or brush over them lightly to mimic the movement from the wind. This will prevent the seedlings from becoming leggy and will strengthen the stems.
For Tomatoes, I recommend planting them in a taller container that you fill up 1/2 way with potting soil when planting so that when the plant reaches the top of the container you can fill the remainder of the way with potting mix since the roots will grow much better all along the stem.
The best way to water the plants is from the bottom so that they absorb the water, you will need to check the plants every day or two to make sure they do not dry out and that the grow lights do not need to be moved up.
Once the plants are getting close to the time to plant them based on their size and the optimum planting date to avoid frost damage you will need to harden off the plants for 5-10 days before planting.
I hope that this article on When & How to Start Vegetable Seeds was beneficial to you and encourages you to grow your vegetable plants from your own seeds or store-bought seeds.