When to start garden seeds

Starting seeds indoors is how many gardeners in Central Kansas grow the specific varieties of vegetable and flowers they enjoy or prefer. The trick is to start seeds indoors at the right time (not too early or late) to allow the seedlings to reach a good transplant size for the garden at the correct time of planting. There is always some flexibility, but knowing the timeframe for seed starting is important. Cool season veggies are often started indoors by early to mid- February, while warm season crops are started indoors by mid to late March or after.

Here are some examples for common veggies based on the 2021 calendar

VegetableStart seeds indoorsTransplant into garden
Cabbage, Broccoli, CauliflowerJanuary 30, 2021March 27, 2021
Lettuce (if using transplants)January 30, 2021March 27, 2021
TomatoesMarch 20, 2021May 1, 2021
PeppersMarch 13, 2021May 8, 2021
Squash, cucumberApril 24, 2021May 15, 2021
These are example dates for 2021, but trends in spring weather vary from year to year in Central Kansas

The following tables provide general timeframes for seed starting in Central Kansas.

VegetableStart seeds indoorsGermination TimeGrowing TemperatureWeeks to grow indoors before transplantingComments
BroccoliEarly February5 to 11 days50 to 60 degrees F7 to 8 Tolerates light frost after hardening.
Brussels sproutsmid to late February5 to 11 days50 to 60 degrees F6 to 7 Tolerates light frost after hardening.
CabbageEarly February5 to 11 days50 to 60 degrees F7 to 8 Tolerates light frost after hardening.
CauliflowerEarly February5 to 11 days50 to 60 degrees F7 to 8 Tolerates light frost after hardening.
*CucumberLate April6 days60 to 62 degrees F3 to 4 Sow in pots. Keep warm at all times.
EggplantLate March7 to 15 days62 to 65 degrees F7 to 8 Keep Warm
Head LettuceEarly February5 to 11 days50 to 60 degrees F6 to 7 Tolerates light frost after hardening.
**Kale/CollardsEarly February12 days50 to 60 degrees F6 to 7 Tolerates light frost after hardening.
*MuskmelonLate April8 days60 to 62 degrees F3 to 4 Sow in pots. Keep warm 
*OkraLate April8 to 14 days60 to 62 degrees F4 to 5 Sow in pots. Keep warm 
Peppermid to late March8 to 14 days62 to 65 degrees F7 to 8
Keep warm. 
*PumpkinLate April8 days60 degrees F4 to 5 Sow in pots. Keep warm 
*SquashLate April8 days60 to 62 degrees F3 to 4 Sow in pots. Keep warm 
TomatoLate March8 to 14 days62 to 65 degrees F6 to 7
Keep warm. 
WatermelonLate April8 days60 to 62 degrees F3 to 4 – potsSow in pots. Keep warm 

*These crops may also be direct seeded into the garden when soil temps reach 60 degrees

**These crops may also be direct seeded into the garden when soil temps reach 45 to 50 degrees

Several other crops not listed such as sweet corn, green beans, beets, or radish are also directly seeded into the garden at the proper soil temps

Flowers Start seeds indoorsGermination timeGrowing temperatureCrop time- weeksComments
AgeratumMid March5 to 9 days60 to 65 degrees F7 to 8 Needs light to germinate.
Alyssum, sweetMid March4 to 9 days50 to 55 degrees F7 to 8Needs light to germinate.
Asterlate March8 to 9 days60 to 62 degrees F6 to 7 
CelosiaEarly to mid March6 to 11 days65 to 68 degrees F6 to 8 Don’t grow cool.
CleomeMid March10 to 13 days70 to 75 degrees F6 to 8 Transplant before flowering.
ColeusEarly to mid March8 to 11 days65 to 75 degrees F6 to 8Needs light to germinate.
CosmosEarly-April6 days65 degrees F4 to 6  
DianthusEarly March5 to 8 days50 to 55 degrees F10 Cover seeds lightly. Grow cool.
Dusty MillerEarly March11 to 16 days60 to 65 degrees F9 to 10Needs light to germinate.
Geranium seedEarly Feb7 to 12 days60 to 65 degrees F12Best if grown in small pot.
GomphrenaMid March10 to 15 days68 degrees F8 to 10 
ImpatiensEarly to mid February15 to 19 days58 to 60 degrees F10 to 12Cover seeds lightly.
LobeliaEarly Feb15 to 21 days60 degrees F11 to 12 Needs light to germinate.
MarigoldEarly April5 to 8 days65 to 68 degrees F6 to 7Tall types require more time.
MelampodiumEarly April7 to 11 days60 to 62 degrees F7 to 8  
NicotianaLate March10 to 13 days60 to 62 degrees FNeeds light to germinate.
Pansy/ViolaEarly to mid-Jan6 to 13 days50 to 55 degrees F12 Grow at cool temperatures.
Orn. Peppermid to late March8 to 13 days60 degrees F9 to 10 
PetuniaLate Feb6 to 13 days55 to 60 degrees F10 Needs light to germinate.
Phlox, annualLate March6 to 13 days50 to 55 degrees F9Direct seed into containers.
PortulacaEarly April6 to 13 days65 degrees F10Needs light to germinate.
SalviaEarly March12 to 14 days60 degrees F9 to 11 Needs light to germinate.
SnapdragonEarly March7 to 13 days45 to 50 degrees F10 Needs light. Grow cool.
ToreniaMid-Feb10 to 19 days55 to 60 degrees F10 to12 Needs light to germinate.
VerbenaEarly March12 to 22 days55 to 60 degrees F10 Chill seeds before sowing.
VincaEarly toMid-March10 to 17 days65 to 68 degrees F12 to 13Grow in warm temperatures.
ZinniaMid-April5 to 9 days60 degrees F6 to 7Direct seed into final container.

The Kansas Vegetable Garden Calendar below can be found in the Kansas Garden Guide from K-State Research and Extension and is a very helpful tool to figure out when crops are generally planted in the garden and harvested.