Seeds in Raised Beds Not Germinating

Q. I have a problem in my raised beds I never encountered before. I can't get seeds to germinate in two of them this year. I have grown produce in them before and the only difference is that I added a lot of oak leaves and clippings from my sage plants this year. I purchased new seeds and replanted but nothing is coming up.

A. The oak leaves and sage clippings would have little effect on the germination of vegetable seeds. Most likely, if it did have an effect you would see very uneven germination of the seed. If you are trying to germinate seeds in the middle of our hot summer in full sun the usual problem is that the soil dries too quickly and prevents seeds from germinating.

Seeds need to stay wet for several hours in order to start the germination process. If you are going to plant seed during hot weather, plant it at dusk and water them in thoroughly so that the seeds have all night to absorb water before the heat of the following day.

This time of year water can be lost from soil at a rate of over 4/10 of an inch a day. Seeds, small seeds in particular, are covered with a very shallow layer of soil. Unless you are watering that soil several times a day, the soil and the seed will dry out causing germination failure.

Covering the soil with shade may be enough to get the seeds to germinate. I use horse bedding or straw to cover the soil after seeding during summer months so that the soil does not dry out so rapidly.

Horse bedding used to improve seed germination and rooting in summer months

Where to get horse bedding for mulch

Horse bedding and straw are very porous but they also shade the soil and slow evaporation. I like horse bedding more because it can be turned under at the end of the growing season more easily than straw and it decomposes faster.

With large seed such as corn, peas or beans, soak the seed for several hours indoors before planting them out of doors. Again, plant at dusk during hot summer months, not in the morning. This allows seed to absorb water at night before getting hit with the sun in the morning.

You can also pre-germinate very small seed but it is more difficult. The seed is soaked in water for several hours and then dried on paper towels. The seed must absorb or imbibe the water but before the seed sprouts. Drying the surface of the seed will not kill the seed as long as it is planted very soon after drying the seed surface. If you soak seed in water, dry it and then do not planted for several hours it is possible to kill the seed. If you leave the seed too long and water and it begins to sprout, the seedling is very delicate at this stage of growth. The first to emerge from the seed is the young root or radical. If you are not gentle with the seed you will break this young root off from the seedling and the seedling will die.

More remote possibilities could be very high salt levels if compost were added to the soil or planting transplants or seedlings into soil which is too dry. This will also damage or kill seedlings and new transplants but the germination should be spotty. I think it is most likely a watering issue and not keeping the soil moist during seed germination.