Planning and Planting Your Seed Saving Garden

Are you thinking of saving some seeds? The best time to start is early, so that you can get your garden planned and planted for success. Below, you will find tips for planning and planting your seed garden, courtesy of Seeds of Diversity's Executive Director, Bob Wildfong. 


5 Tips for planning and planting your seed garden - sunlight, spacing, watering, succession of plants, interspacing with short season crops



1. Get Enough Sun.  

Most plants prefer full sun to make good quality seeds. That's because plants are solar-powered, so they grow to maturity faster and stronger when they get lots of sunlight. In a city garden it can be challenging to find sunny places among the trees and buildings, so gardeners often grow leafy plants like lettuce and spinach in shade or part shade, because they can tolerate less sunlight. The reason is that plants need more energy to produce fruit and seeds, than they need for leaves - which is why many plants will survive in shady places, but not bloom.

If that's your strategy with greens, remember that you're growing seeds now. Spinach, lettuce, chard, and other leafy vegetables are fine in partial shade if you just want the leaves, but they need more solar energy to produce flowers and seeds.

2. Isolate Varieties. 

You've heard this before, but that's because it's so important. If you want your seeds to be "true to type", which means they will grow the same as the plants they came from, you have to prevent them from being cross-pollinated with other varieties. Learn which plants cross with each other (pumpkins cross with zucchini, but not with watermelons) and how far apart you should plant them to limit their crossing. Also keep in mind what your neighbours are planting, and how far away their gardens are.

If in doubt, there are many references for isolation, including our book How to Save Your Own Seeds.  The easiest vegetables for small garden seed saving are: tomatoes, beans, peas, and lettuce. We recommend at least 3 m (about 10 feet) of space between different varieties for home seed saving (more for commercial seed production).

3. Don't Baby Your Seed Crop. 

You want all your plants to grow perfectly, but there's that corner of the garden that always dries out, or where the soil is crustier and the lettuce always bolts. Use that to your seed-saving advantage! Every gardener learns to keep lettuce tender, radishes mild, and mustard greens lush by giving them plenty of water, rich soil, and lots of tender loving care. The reason is that they go to seed otherwise. Take Nature's hint, and let your seed crop struggle a little. You'll get more seeds, and they'll ripen earlier.

4. Leave Extra Space, and Time.  

You harvest tomato seeds from ripe tomatoes, and pumpkin seeds from ripe pumpkins. But keep in mind that your seeds for lettuce, cucumber, broccoli, zucchini, radishes, all biennial vegetables, and anything that you eat before it bears seeds, will need more time to grow than you're used to. Also, the plants will grow taller and/or wider when they grow flowers and seeds.

For example, you can easily grow head lettuces spaced a foot apart, but you'll want at least a foot and a half between them when they grow to full seed-bearing size. Also, that will take about five extra weeks after the time you would normally eat the lettuce. One strategy is to plant at your normal spacing, and eat every other head, to give the rest more space to grow to seed. Depending on the variety and your climate, you might also want to start your lettuce seeds indoors so they have a good chance of seeding during the dryer part of late summer.

5. Plan Succession with Seed Harvests in Mind.  

Lastly, while you think about the longer season needed for greens, annual root vegetables and soft fruit like cucumbers and zucchini to set mature seeds, this is a good time to plan how you will rotate your planting during the season.

If you normally plant radishes in spring, harvest them within a month and re-sow that space with green bush beans (a smart plan if you're a non-seed-saver), you'll have to change that plan if you're growing the radishes for seed because they'll need half the summer to mature. Maybe you don't need the whole row for seed (a dozen radishes will give you plenty of seeds). Leave one end of the row to grow to seed, and harvest the rest of the radishes for eating. Then re-sow the harvested part with short-season spinach that will finish at about the same time as the radishes go to seed. You could end up with a more complicated garden, part-rows maturing at different times, but most of us end up with something like that at the end of the season anyway, seed saving or not.



1. Give More Space  

You might be accustomed to planting your greens close together. You normally harvest them before they grow large, because they're more tender and mild-tasting when they're young. And besides, crowding tends to prevent them from growing too large. But if you're growing the plants to seed, they need lots of room to grow fully, make flowers, and form seeds.

Leave at least a full foot of space around each of your lettuce plants if you want to get seeds from them. Remember that they'll grow 3-4 feet tall, and many varieties will be at least a foot wide at the bottom.

A great strategy is to plant lettuce and other greens closely, but when you harvest them to eat, leave one in the ground about every foot, to grow to seed. That way, you make use of the space when the plants are small, and give your seed crop the space it needs.

If that's your strategy with greens, remember that you're growing seeds now. Spinach, lettuce, chard, and other leafy vegetables are fine in partial shade if you just want the leaves, but they need more solar energy to produce flowers and seeds.

2. Seeds Need Sun

Plants are solar powered, and flowers and fruit need a lot of energy to grow. Since seeds come from fruit, and fruit come from flowers, you'll find that a seed crop needs more sun than the same plant would need to grow leaves.

For example, you can grow nice spinach or kale in part-shade. The leaves don't need intense solar energy to grow, and though thye might take a little longer to grow, you'll get tender greens. However, if you want lettuce or kale seeds, the plants have to grow a lot more, and they need more energy to do that. Sow your eating greens in part-sun, but save your sunny spots for the seed crop.

3. Water Only When Necessary

You water your garden when it's dry, because the plants grow more tender, fuller, and faster. That's important when the soil is really dry. But if the soil is just a little on the dry side, watering really only matters for crops that will become bitter, strong-flavoured, tough, or stringy. For instance, lettuce and radishes get that way when they grow in dry soil.

For a seed crop though, it doesn't matter whether the radishes get too spicy because you won't eat them anyway. It matters more that they produce flowers and seeds. Nature's way of dealing with drought is to coax plants to make seeds faster; to reproduce quickly so new seeds can survive any dry days to come. Use that to your advantage, and only water when the plants show signs of being really dry (if the leaves droop, you're not helping by withholding the water anymore).

4. Sow Biennials Later in the Season

Many biennial vegetables, such as beets, carrots, turnips, and cabbage can handle some frost, so it's common to plant them early in the spring. That's excellent if you're going to eat them, because you get a longer season of produce.  But if you plan to save seeds from those plants, sow the seeds a little later in the season; about 70 days before the end of the season (for most of us that's sometime in June). The reason is that smaller roots often store better over winter than large ones.

Imagine if you sowed beets in early May, and kept them in the ground until September to store over winter for seeds next year. Those beets would be huge. It turns out that they won't store as reliably as if they were only a few months old. Think of it this way: if you use a succession of sowings, say to get beets and carrots in several separate harvests during the season, your biennial seed vegetables should come from the last of those harvests, because then they will be just the right size for storage until next year.

5. Interplant Short Season Crops with Your Seed Crops

Although the first tip says you should leave lots of space between your seed plants, they only need that extra space when they grow up. While they're small, they can co-exist with other small plants just a few inches away. For example, lettuce needs at least a foot of space around it when the plant is mature with flowers and seeds, and radish plants can grow up to three feet tall when they bear seeds. However, during the first 4-6 weeks of their lives they are small, and you can grow and harvest short-season plants right next to them.

Sow spinach just 6 inches next to the radishes you want to grow for seeds. When you harvest the spinach, let the radishes fill the space.

Sow arugula, cress, or kohlrabi just 8 inches next to the lettuce you want to grow for seeds. When you harvest the greens and small kohlrabi after about 5 weeks, let the lettuce fill the space.

You can also grow baby beets, baby carrots, and other varieties of radish and lettuce this way (just be sure to remove plants of the same species as your seed crop before they flower, so they don't cross-pollinate).