If you want to know how to grow penstemon from seed in the UK, you can simplify the process into three steps. The procedure itself is not complicated, but it would help to have some knowledge of starting plants. More so, growing penstemon from seed would be more comfortable in the polytunnel to guarantee germination.
Speaking of germination, one of the best things about the perennial penstemon is that it is relatively easy to grow from seeds compared to other plants. Let’s say you don’t want to do stratification or a pre-germination treatment before sowing. You can choose penstemon species that will germinate without this process, but you can always use the polytunnel to break the seed dormancy if you have no choice.
Learn How To Grow Penstemon From Seed In The UK In 3 Easy Steps
Step #1. Seed collection
Penstemon seeds mature in autumn, and you can collect the seeds yourself for planting. If you don’t have penstemon in the British garden, you can also collect in the wild, but check your county regulations when doing so. If you want, you can also get your seeds from the American Penstemon Society.
Most gardeners in the UK also recommend storing penstemon seeds for six months to one year before using them. Remember that a 100% germination rate is not easy to achieve with seeds, so it’s better to store them for a while before sowing. You can use paper envelopes and place them in a cool, dry place until use.
Step #2. Pre-germination treatments
As mentioned earlier, some penstemon species require pre-germination treatment such as ageing, stratification, chemicals, scarification, and changes in conditions of light and temperatures. The techniques you’ll do may change as the years pass, depending on which you notice would be the most effective. But more than these treatments, the key to growing penstemon from seeds meant sowing a high number of seeds.
To give you a general idea of pre-germination procedures, you can stratify the seeds. One helpful technique for northern penstemon species is growing the seed at above freezing temperatures in a moist medium. Another example is sowing the seeds in a lightly covered pot of moist perlite and vermiculite outdoors in winter or a sandwich bag in the refrigerator.
The seed germination itself can happen in months or years, and the environment’s conditions play a role in how soon it starts. Either way, don’t forget to transfer the seeds to a warm location and receive light once germination occurs. You can use the polytunnel to maintain 40 to 60°F to encourage the young penstemons to grow.
Another method to encourage seed germination is by scarification or removing the seed coat. By doing so, you can break the dormancy of the seeds. Cutting or causing an abrasion on the seed coat is especially useful for some penstemon species, such as the Penstemon haydenii.
Step #3. Planting
How does one plant a penstemon seed? You can plant penstemon seeds directly in the ground by scattering them in the autumn, and the ideal location should have shade but still receives rain and snow. Similar to planting other plant seeds, make sure to prepare the ground first by loosening it.
When you scatter the seeds, they should have enough space among them to anticipate their growth. Once you have them thinly on top, you can use potting soil or coarse sand to cover them lightly. The beauty of penstemon seeds is that they don’t require other tedious practices, and they should sprout well by spring.
You can then gauge if you can transplant them by the middle of the season. However, make sure that you mist the medium well or provide supplemental irrigation as you’re waiting for the leaves to emerge. Once the seeds grow two pairs of true leaves, you can replant them in separate containers with fertiliser.
Thepolytunnelcan still accommodates these penstemon plants, but remember to gradually expose them to outdoor challenges if you plan to have them outside. Keeping them outdoors means hardening them against wind, sun, and dryness, in addition to having protection for the first week outdoors. Nonetheless, take comfort in the fact that penstemon is resistant to heat, drought, and animals.
Whether you collected them yourself or purchased them, you should be excited to root penstemon seeds. It can be overwhelming to learn how to grow penstemon from seed in the UK, especially when some species require pre-germination treatments. However, the process of growing the plant itself only takes three steps, and you can consider the pre-germination treatments as an added UK gardener skill.
Start by collecting the seeds and store them for six months before you begin sowing. And while not all species require a pre-germination treatment, both stratification and scarification are reasonably easy methods to do anyway. You can then plant the penstemon, where it receives rain and snow and has a shade for sunlight.
They should grow by spring and be ready to transplant in the permanent areas of your UK garden by the middle of the season. Overall, growing crops from seeds can be daunting, but don’t get discouraged by the methods for breaking dormancy in some seeds. You can also use polytunnel to make germination easier and faster by providing the optimal conditions.