Hi, thanks for the question.

You may be spot on. Compost, particularly when it's not fully processed, can indeed interfere with seed germination. You do need to consider soil temperature, adequate water, correct planting depth, and the quality, age, and storage of seeds for successful germination. Who would think that improperly processed compost may lead to germination failure.

Some materials in compost can prevent certain seeds from sprouting. For example, coffee grounds may boost the germination of some seeds but suppress others, which is why it's advised to keep their proportion below 20% of the compost's total volume. Black walnut leaves are known to inhibit seed germination. Unfinished compost containing phytotoxic substances can particularly affect sensitive seeds such as cress and beans. Soil with high clay content or excessive plant residue can also hinder proper germination and seedling emergence. Additionally, overly moist compost might restrict the necessary gas exchange for seeds to germinate. Effective composting requires a balanced mix of green (nitrogen-rich) and brown (carbon-rich) materials, and regular turning of the compost to facilitate decomposition and avoid creating any germination-inhibiting compounds. For planting, it's crucial to use mature, thoroughly decomposed compost. Here are some links that may be helpful:

Search Results for “compost soil mix” – The Garden Professors™

Home Composting: A Guide for Home Gardeners (psu.edu)

Contaminated Compost Equals Gardening Problems // Missouri Environment and Garden News Article // Integrated Pest Management, University of Missouri

I hope this is helpful.