Most Frequently Asked Questions About Growing Sweet Peas
Should I soak or not?
Everyone has differing opinions about this, so it gets confusing for new growers. It really is up to personal preference. I know growers who swear by soaking and others who say absolutely not. We have done both and find there is only a slight difference in germination so either is fine. If soaking, make sure to only do so for no more than 24 hours. Soaked seeds will typically germinate in about 7 days. If not soaking, thoroughly wet the soil before planting then let dry out between subsequent waterings. They should germinate in 7-10 days with this method. Our preferred method is to place the seeds in a paper towel inside of a Ziploc bag and use a spray bottle to wet the paper towel. Then store in a cool room and the seed should germinate in about 5-7 days.
What temperature should I keep my seedlings at?
You want your temperature to be between 50-65. Sweet peas are cool season annuals and prefer to grow slow and cold. Below 50 or above 65 could hinder germination so it is important to keep them consistently in this temperature range.
It's been over a week and they still haven't germinated!
It's time to check your seeds. Dig down into the dirt so that you can see and touch your seed. If it is still small and hard, try soaking it and nicking the seed coat. If it is swollen and plump, give it more time as this is what they should look like. If the is mushy or moldy, start over with new seed.
When should I start my seeds?
If you want to grow them with minimal added heat, start 10-12 weeks before last frost date. If you are growing them in a greenhouse, you can wait until 6-8 weeks before last frost. If you are in a warm growing zone, start them about 8 weeks before first frost in the fall and do a fall planting instead of spring planting.
How do I nick the seed coat?
Sometimes seeds are stubborn, and you need to nick the outer coat. Take your fingernail or a butterknife and gently remove the sliver of the out coat. Be careful not to cut into the seed itself. For comparison, think about an onion. The outer papery peel is the thickness you are taking off of your sweet pea seed.
When should I pinch?
When you have about 4 leaf sets you can pinch them. Take some flower snips and cut off the top 1-2 leaf sets right about the leaf set below. You should leave 2 sets of leaves on the plant. This will encourage branching and create a stronger, bushier plant. For a fun experiment, take the part you cut off and try rooting it.
What size pot should I start my seeds in?
In an ideal world you would start them in a pot style called a root trainer. These are about five inches deep which allows for good root growth. For most of us, we are not in an ideal world so, grab what you have. We have planted in everything from 72 cell trays to cut paper towel rolls. Keep in mind, the smaller the pot you have, the quicker you want to get them into the ground.
When should I transplant?
Sweet peas like it cool. They can tolerate light frost and should be transplanted around your last frost if doing a spring planting. Our last frost is typically the first week of April and we have planted at the earliest starting in mid-March and latest end of April.
How close do I plant them?
A minimum of 6 inches apart is best but you can go up to 12 inches. We grow ours at 6 inch spacing and it creates a beautiful bushy wall of sweet peas.
Do they cross pollinate?
Sweet peas are self-fertile and do their pollinating before they even flower. The little flower bud that you see is where the magic happens. This means that you can go ahead and plant varieties next to each other and still be able to save variety specific seed in the fall.
Did I water too much or not enough?
The biggest challenge to growing sweet peas from seed is getting the watering right. Since they are grown at cooler temperatures, rotting is a major concern. You want to make sure you are allowing the dirt to dry out between waterings. Keeping the dirt constantly wet will encourage fungus and rotting.
What kind of lighting do I need?
Nothing beats sunlight. This is why it is preferred to have a greenhouse to grow your seedlings in. That being said, daylight wavelength grow lights work well for in the house growing. You can get shop lights from Home Depot/Lowes with a daylight bulb(5000K). A windowsill is fine for initial germination but will not be sufficient for growing the seedling and will result in a leggy, weak plant.
Why are my plants leggy?
This could happen for one of two reasons. Either you are growing them too warm and need to move them into a cooler area OR you have the light source too far away and need to move them closer. The sooner you notice this and correct it, the stronger your plant will be. If they are already leggy, pinching them and planting them a little deeper when you transplant them should help correct this.
Important note for growing!
Our indoor growing areas do not properly prepare the plants for the outside world. Adding a gently blowing fan or brushing them with your hand a few times a day helps strengthen the stems to be about to withstand wind and rain when transplanted outside.