Green Tips – Seed collecting: creating a perennial paradise

A delightful long border, full to the brim with perennial delights, is top of the wish list for most enthusiastic gardeners and, while buying enough plants to create an interesting border can be pricey, seed collecting is a free and fun way to increase the number of plants in your garden.

Seeds can be collected and saved from trees, shrubs, perennials, alpines, vegetables and herbs.

Our herbaceous areas at the castle provide plenty of opportunity for us to collect seed. This year we had marvellous displays of echinacea in Faith’s Garden and magnificent stipa grasses; both of which are ripe for seed collecting now.

Wait until it is dry

When collecting seeds it’s important not to jump the gun: immature seeds won’t germinate for you. You also need to look to the heavens and collect on a dry day. If it’s a dry day and the plants are ready, then choose a healthy and vigorous plant to collect from.

Look for seed pods which have changed colour from green to brown, then cut or pick the seed heads and lay them out to dry somewhere warm. If the pods aren’t fully open, wait until they have dried, then gently crush the pods to release the seeds.

Some seed heads explode like firecrackers, so they need to be checked every day. You could place the seed heads in a brown paper bag and wait for them to explode, or shake them.

Clean and store

Once the seed is free, make sure you clean off the chaff to prevent the seeds from rotting.

Most seed can be kept (hellebores are an exception and prefer to be sowed immediately). Dig out your stash of old envelopes to store them and make sure you label them correctly: it’s often hard to work out which seed is which a few months down the line!  

I do know of gardeners who keep their seed in a Tupperware or airtight container with silica gel, to absorb excess moisture. It’s also good to store seeds at 5c as they can remain viable for long periods if refrigerated. 

Collecting your own seed is rewarding not just because it provides you with free plants for the coming year, but also because it is a really good old-fashioned way of interacting with nature.

Collect seed from these plants in September

If your cosmos have avoided the damp then these are great little seed providers. Zinnias are great too and their seeds usually last for a year or two.

Divide your plants!


(Above: Verbena reseed themselves but you can collect seeds and split the plants too!)

Another great way of maximising your plants for the next season is to divide your perennials in September. Lily of the valley, delphiniums, geraniums, hostas, salvias, verbena and eryngium are all fantastic dividers!

  • Take your garden fork, place it gently under the plant and lift. You’ll notice that they may have buds at ground level
  • Shake off any soil so you can clearly see the roots of your plant, then you can either gently pull the plant apart with your fork or with your hands. In some cases, you may need to use a garden knife on the roots
  • Once you have divided the plant, you can plant them back in the same situation or utilise a planting plan to create a repeat pattern further down your border
  • Remember to water well when you replant your divided specimens

Discover more at Hever Castle and Gardens.

Neil Miller at Hever Castle

(Above: Cosmos are fantastic seed producers that you can collect from in September)


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