Lindheimer’s senna (Senna lindheimeriana)
How to Prepare Seeds for Sowing
SEEDS HAVE EVOLVED TO WEATHER the storms of time and temperature. These seed-sowing tricks will help you mimic nature’s processes to increase germination, improve yields and create strong, uniform gardens.
Scarification means scratching or nicking the seed coat. It’s a good idea to scarify anything with a hard seed coat, such as Texas bluebonnets (Lupinus texensis) and Texas mountain laurel (Sophora secundiflora). It can mean the difference between getting one or two plants out of 50 seeds and closer to 100 percent. The appropriate method depends on seed size.
For bigger seeds: We recommend using a stone grinder, holding the seed with needle-nose pliers and making sure not to let it heat up.
For smaller seeds: We suggest dipping in sulfuric acid. For thin coats, five minutes or less should work, while thicker coats may take up to 30 minutes. Be sure to rinse the acid off really well, otherwise it can eat through and kill the plant embryo.
Other methods include:
- Lacerating seed with a sharp knife
- Nicking seed with nail clippers
- Roughing up the seed coating with sandpaper
- Freezing overnight, then adding seed to boiling water (cooled just a bit) in order to cause cracks
One important thing to remember— by scarifying you are increasing the number of germinated seeds that are vulnerable to extreme weather conditions. Once scarified, most seeds will germinate quickly, and the seedling will require water. You must be ready to water if you are going to scarify the seed.
Stratification involves putting seed in a plastic bag with growing media (we suggest vermiculite for smaller seeds, perlite for larger) and chilling it. This serves as a sort of simulated winter.
The amount of time a seed is in the cold depends on the plant:
- Perennials such as milkweeds, columbines and penstemons can be stratified from two to four weeks.
- Stratify trees and shrubs for 30 to 90 days.
Be sure to check your bag daily and keep the media moist. If you see germination, go ahead and sow the seed in soil.
Ready to get sowing? Browse our list of native seed suppliers.