2016 / How-to

Seeds 2

When to Plant?


In our last blog, we talked about what to grow and where to grow it. This time, we will talk about knowing when to plant your seeds so that they will be ready at the right time for planting outdoors.

Why is this important? Well, different types of plants mature at different times. This is for a number of horticultural reasons that are fascinating to us but will most likely bore the average reader to death, so  we will leave that for another time and place. But suffice it to say that they do. Lettuce will mature in 65-80 days, for example, while Lavender can take up to two years. The trick is to know this in advance, and plant the seeds so that they haven’t outgrown their pots before it’s safe to plant them out. Luckily for us, the seed companies make this easy by printing the information that we need on the back of the seed packet.

If you get out a seed packet and turn it over, you will most likely see this kind of information:

Seed packet

This is the back of a packet of Portulaca seeds. In the boxes can be found a wealth of information:

Type: Annual. This means that it will die when winter comes and won’t come back next year.

Planting Depth: 1/4″. This basically means that the seeds need darkness to sprout, so a thin layer of soil should be sprinkled on top of the seeds when they have been scattered on the soil.

Thin to: These particular seeds are very small and planting them 6-8″ apart would require tweezers, a magnifying glass, and an unlimited amount of patience, and is not worth the bother. What this box means is that after the seeds have sprouted and are growing nicely, you should snip off some of them so that they have plenty of room to grow.

Sun/Shade: This tells us that Portulaca will enjoy being planted in the sun.

Height: This tells us how tall the mature plant will be.

Days to Germination: This means the amount of time that it will take the seeds to sprout, if given the right conditions. In the case of Portulaca, 7-10 days.

Direct sow: “After danger of frost”. This means that if you want to plant the seeds  outside instead of starting them indoors, you need to plant them after there is no risk of the plants getting killed by a frost. More about this later.

Start indoors: This tells us how long BEFORE the last expected frost in your area you should sow the seeds. Again, more about this in a minute.

Blooms: When the plant blooms. In this case, summer. As opposed to spring or fall; you get the drift…

At the bottom of the packet is a date. This is the date that the seeds should be sold by, as after that date, fewer and fewer seeds in the packet will sprout. You can still use them a year or two or more after the sell by date and you will still get some good plants, but you will get more the fresher they are.

There is also a lot number, but that is for the seed company’s purposes, so you can ignore that!

As you see,there’s a lot of information on the back of a seed packet!

Are you with us so far? Sound easy? All except the bit about the last frost date, perhaps? Well, luckily for us, there is a website that can help. Click here and you can enter your zip code and get the average last frost of the winter. Then all you have to do is work backwards from that with the aid of a calendar. For example, the website says that the average last frost date for North Hampton, NH (03862) is May 16. It also says that it is almost guaranteed that there will not be a frost after May 28. How much you play it safe is up to you, but going with the average last date and then playing it by ear when the time comes, is a sensible way to go.

With that in mind, look at the back of the seed packet again, and look at the box that says when to start indoors. In the case of the Portulaca, you can start the seeds indoors 4-6 weeks before the last frost, or 4-6 weeks before May 16. If you count backwards on the calendar, you then see that a good time to plant the seeds would be between April 4 and April 18th. And there you have it!

If you have a lot of different types of seeds to start, then a chart is really helpful to get organized. You can create your own, or simply write it on a calendar, or copy the chart below.

Seed chart

Once you know when to plant your seeds,the next step is to  plant them. Tune in next time for the “how”! But for now, get yourself a cup of something hot and chart your way to seed starting success!

Any questions?


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