Our guide to seed sowing compost (2024)

FAQs

Should you use compost when starting seeds? ›

The Danger of Starting Seeds in Compost

​There is a pretty significant drawback to starting seeds in compost, damping off disease. Damping off disease is a common term used to describe a group of soil-borne fungal diseases that affect the seeds and seedlings of plants. These diseases can be caused by various fungi.

When saving compost for reuse, separate your seed compost from your potting compost. Seed compost is generally finer and contains fewer nutrients. It can be used several times over for germinating larger quick growing seeds such as beans because all these seed require is a medium to grow in, some water and light.

And if you're going to pay to have your lawn overseeded, you want to ensure it's going to work and actually grow in your soil conditions. We spread ½ inch of compost over the targeted areas in your lawn. Having nutrient-rich soil helps lay the groundwork (pun intended) for having your lawn overseeded.

Too dry, and your seeds won't germinate. Too wet, and they're liable to rot. Ensure that seeds are kept evenly moist by thoroughly wetting and draining the compost before you begin.

Seedlings are tiny and delicate and therefore need a light compost that they can push through as they emerge from their seed. Anything too heavy will smother the seedlings before they've had chance to surface. This leads to poor germination rates and unhealthy plants.

If you are trying to grow potted plants indoors or outside, compost is a solid choice. When supplemented with liquid fertiliser, it can make sure that your seedlings have all the nutrients they need for rapid growth and make sure they are ready for transplantation.

However, all purpose, multi purpose or garden compost should not be confused with seed compost. Any type of compost can be designed to be peat free, but seed sowing compost is designed to support sowing seed and support young plants straight from the seed packet.

For an all purpose compost, Coco Grow + is an ideal option with this compressed blend of 80 per cent natural coco coir brick and 20 per cent perlite. This is perfect to use for sowing seeds and potting, rooting cuttings, or potting succulents. But it's also suitable for general planting in the garden.

“Seed starting soil may include several items including moisture-retentive organic matter like peat moss, coco coir, fine compost, composted tree bark, or leaf mold and porous material to assist with good drainage, such as perlite, vermiculite, or sand,” Clausen says.

Vermiculite is better for water retention, that also means in that moisture it retains key nutrients for your plants and cuttings to soak up. Perlite works better to help drainage, this means its also better for loosening heavy, compacted soil.

Can you plant seeds in straight compost? ›

In addition to hearing individual gardeners recommend against starting vegetable seeds in compost, two books that I like both recommend starting seeds in mixes that do not include compost.

Peat-free composts are a good option for seeds and cuttings. But if you're used to peat-based composts, you may need to make a few adjustments to your plant-care routine to achieve the best results, as we explain below.

Old mix can, however, be sterilized for reuse. It will not be as fresh, but the sterilization process will ensure it is pest and disease free. In fact, I sometimes sterilize fresh seedling mix when I am starting prized seeds.

The compost slowly releases nutrients into the mix, which will help to feed seedlings as they grow. You can use your own garden compost, or buy some in.

Seedlings are tiny and delicate and therefore need a light compost that they can push through as they emerge from their seed. Anything too heavy will smother the seedlings before they've had chance to surface. This leads to poor germination rates and unhealthy plants.

Combine compost, topsoil, a bit of coarse sand, and something like vermiculite, perlite, or coco coir until you have a mix with a consistency that holds together when wet. For seed starting, you'll avoid using as much sand as you would when making soil for your garden.

This can help to protect plants from harmful pathogens. However, over time, the microbes can use up some of the available nitrogen in the compost, so extra feeding may be required. Peat-free composts are a good option for seeds and cuttings.