Growing Coastal Redwood from seed

Coastal Redwoods, otherwise known as Californian Redwoods or by their botanical name Sequoia sempervirens, are the tallest trees on the planet (the tallest being measured around 115m). Their distinctive red bark is similar to that of the closely related Giant Sequoia – but their fully formed shape is usually slightly skinnier and taller. The foliage also differs, with flattened out leaves able to that capture light and moisture. As their natural habitat encounters milder winters than the Giant Sequoia, there is less need for cold stratification to break dormancy in Coastal Redwood seeds – many arguing it isn’t needed at all. In addition to seed reproduction, the the Sequoia sempervirens can also reproduce readily through shoots, and by human intervention, through cuttings that produce clones of the parent tree. All of these factors make the specie easy to work with as a tree grower. This guide will cover the basics you should know to get your Coastal seeds germinating.

A Coastal Redwood in the UK, with a car for scale

Sourcing Coastal Redwood Seeds

Buying seeds

If you live in the UK, you can buy your Coastal Redwood seeds directly from us! Not only is our seed good quality and competitively priced, it also helps to support the production of these free growing guides. You can find our Coastal Redwood seeds here. If you live outside of the UK, search for local seed sellers in your region.

Collecting seeds

Self-collected Coastal Redwood seeds tend to have good germination rates, even from younger trees outside of their natural habitat. If you have a Coastal Redwood nearby you may wish to consider the option of collecting your own seeds – just check if you need permission to collect the seeds before doing so. The best time to collect cones is September to October, as the seeds mature in one growing season.

Preparing your seeds

Preparing Coastal Redwood seeds is a relatively straightforward process, as they can germinate well without any stratification. This is because the natural habitat of the species experiences mild winters that rarely drop below 4-5 degrees celsius as a nighttime low.

Whether you’re stratifying your seeds or not – the best place to start is with an overnight soak in water to kick start the process.

Often your best option will likely be to then move forward to sowing as soon as you are able to, as the seeds have a relatively short shelf-life – especially when stored at room temperature or higher.

If you do decide to stratify your seeds, the best approach would be to keep the seeds moist but not totally wet (optionally with a medium such as vermiculite or sand that can help maintain and regulate moisture levels across the seeds) and place them in a semi-sealed container in the refrigerator for 3-6 weeks – ensuring they don’t dry out during this time.

A hand full Coastal Redwood seeds

Sowing Coastal Redwood seeds

As with most seeds, our preferred method is to sow outside of compost and wait for germinations before planting germinated seeds in seed tray pods. This approach takes away a lot of the guesswork and is generally more efficient as you’re not wasting space on seeds that won’t germinate.

The method involves sowing the seeds on a damp tissue paper inside a sealed container that maintains a relatively high humidity. The trick here is to get the level of moisture right. Too much and you are at high risk of fungal growth that can damage the seeds. Too little and it will be difficult for them to germinate. My usual method involves first inserting the kitchen roll, then giving it a few sprays with water from a spray bottle so that it is slightly damp. I then place the seeds onto the roll before spraying another few sprays. If you’re worried you made things too wet, you can leave the lid off for a few minutes to let them dry out. These germination containers should be sealed and placed in a shaded area (away from any direct sunlight) and kept at a comfortable room temperature (around 20 degrees celsius). You will need to check on the seeds daily for germinations.

After germination

When you spot a germinating seed, it’s time to plant it in compost. I use a coir compost for this stage as it is light and airy – allowing the roots to grow easily and without becoming too saturated in water. A key risk in the first few weeks of life is death from “damping off” – essentially fungus that kills the seedling – in my experience using coir compost helps to reduce a large part of this risk as long as you’re not overwatering. Germinated seeds should be planted around 0.5-1cm below the surface.